Engineered microorganisms, as the core driving force of biomanufacturing and the development of the new bio-economy, demonstrate increasingly prominent strategic values. The newly built Engineered Microorganisms and Genetic Tools Collection Center of China (EMTCC) supported by the Ministry of Education aims to break through the limitations of “microbial culture collection centers” and provide a comprehensive resource innovation service platform supported by information technology and integrating resource acquisition, intelligent creation, data analysis, and open sharing functions. This platform intends to meet the needs of basic research, technology development, and industrial applications. This article elaborates on the building framework of EMTCC, which takes large-scale resource preservation as the basis, intelligent mining and analysis as the core, and digital storage and computing sharing as the link. By carrying out large-scale acquisition and standardized preservation of natural and engineered microorganisms and plasmids and integrating cutting-edge technologies such as high-throughput automation, multi-omics, single-cell analysis, artificial intelligence prediction models, and digital twins, the EMTCC achieves a complete process of “acquisition & preservation, analysis & identification, and data sharing”. On the basis of drawing on the standardization and quality control systems of internationally renowned institutions such as American Type Culture Collection (ATCC), a resource repository model integrating living “organisms, information, and intelligence” will be developed. This innovative practice is expected to provide strong resource guarantee and technical support for research innovation and industrial upgrading in the fields of synthetic biology, metabolic engineering, biomedicine, and environmental remediation.

The dynamic balance between the preservation and distribution of microbial patent strains, the “gene chips” of biotechnology, has become a crucial benchmark for assessing a country’s competitiveness in the bioeconomy. By comparing the global data on the preservation and distribution of patent strains from 2001 to 2023, this paper systematically analyzes the gaps between China, the United States, and other countries in terms of resource reserves and circulation efficiency. The results revealed that while China was a global leader in preservation volume, its strain distribution rate lagged far behind the international level, which restricted technological innovation and industrial transformation. This study proposes comprehensive strategies such as optimizing the preservation systems, enhancing policy coordination, promoting industry-education-research collaborative innovation, strengthening international cooperation, and applying artificial intelligence and blockchain technologies throughout the entire chain. These strategies are designed to enhance the utilization rate of microbial strains, activate the value of China’s patent microbial resources, and position China at the forefront of the global bioeconomy.

China’s national food security faces rigid constraints due to land scarcity, a large population, and heavy reliance on imported feed proteins. In this context, the initiative to seek calories and proteins from microbes has become a strategic priority for building a diversified food supply system. Microbial alternative proteins represent a quintessential new quality productive force in agriculture. They offer distinct advantages, most notably high industrial efficiency and the ability to decouple protein production from food crops and arable land. This paper reviews China’s progress in this sector based on global biomanufacturing trends. The discussion focuses on synthetic biology-driven strain engineering, gas fermentation, and industrial-scale production. Furthermore, the article critically analyzes current bottlenecks, including intellectual property barriers for elite strains, high production costs, and lagging safety evaluation standards. Finally, we propose targeted recommendations to address these challenges. These include strengthening organized basic research, establishing an intelligent manufacturing system that integrates education, technology, and talents, and reforming regulatory frameworks. These insights aim to provide a strategic reference for China to secure a commanding position in the global bio-agriculture landscape.

The dark matter of microbes, encompassing uncultivated microbial taxa and unknown biological features, has been widely accepted by microbiologists. With the advancement of microbial investigation methods, a series of dark matter concepts related to microbes have been successively proposed, and numerous research advances in this field have been well-documented. However, these concepts exhibit complex and overlapping connotations, and their inherent connections and distinctions have not yet been clearly clarified. This review work systematically summarizes the current conceptual frameworks of different dark matter types of microbes and analyzes the relevant investigation methodologies and their development trends. This article will help researchers in the microbial resource field gain a clearer understanding of the conceptual connotation and current research status of microbe-associated dark matter and promote the in-depth development of dark matter resource mining.

The application of natural microbiomes is limited by their complex composition and uncontrollable functions, which makes synthetic microbiomes a core direction in microbiome engineering. Early binary synthetic microbiomes can achieve functional synergy under controlled conditions, whereas they exhibit poor stability and limited functional persistence in real complex environments due to their simple metabolic pathways and insufficient ecological redundancy. In recent years, the research on synthetic microbiomes has shifted from an empirically driven approach to rational design, achieving significant progress in strain resource acquisition, construction strategies (top-down, bottom-up, and their hybrid paradigms), and computational tools (e.g., genome-scale metabolic models). However, current design frameworks still focus primarily on functional realization, with insufficient attention paid to the long-term stability, system robustness, and multi-level ecological interactions of communities in complex environments. This paper systematically sorts out the evolutionary trajectory of synthetic microbiome construction paradigms and reviews the key elements for enhancing community stability. By establishing a multi-level metabolic network, this paradigm significantly improves the functional persistence and ecological robustness of synthetic microbiomes in complex and fluctuating environments. The future research on synthetic microbiomes needs to further integrate multidisciplinary technologies to improve the predictability and long-term stability of engineered microbiomes, providing a systematic theoretical framework and research directions for constructing highly robust synthetic microbiomes.

Microorganisms, as the oldest and most diverse life forms on Earth, possess significant development value due to their differentiated metabolic potential and biosynthetic capabilities, serving as core resources for the development of novel drugs and natural active products. Currently, the deep integration of artificial intelligence (AI) with microbial strain development is driving a paradigm shift in life sciences from “empirical screening” to “rational design”. This shift is driven both by the limitations of conventional research methods in addressing the complexity of microbial resources and by the unique advantages of AI in multi-omics data analysis, model prediction, and experimental process optimization. This article systematically reviews the roles of AI in the development and application of microbial strains, covering four aspects: strain breeding, metabolite development, disease diagnosis and treatment, and xenobiotic synthesis. Additionally, it discusses the core advantages and existing limitations of AI in the strain development process. In summary, through automated modeling and scientific prediction, AI not only accelerates the efficiency of microbial strain development but also provides multi-dimensional optimization strategies, serving as a core driver for technological innovation. The integration of AI is expected to break through traditional industrial bottlenecks and promote the sustainable development of the microbial industry.

Heavy ion radiation (HIR) is effective for generating new germplasm in plants and microorganisms due to its high mutation induction rate, broad mutagenesis spectrum, and excellent stability of mutants. However, the random mutagenesis induced by radiation limits the efficiency and quality of HIR-based mutation breeding, which has become a key problem to be tackled. According to the process of heavy ion radiation-based mutation breeding, this review proposes a set of tandem strategies to enable efficient and high-quality HIR-based mutation breeding practices. These strategies include adjusting the radiation parameters from multiple dimensions, regulating cellular sensitivity to radiation damage and damage repair capacity, combining heavy ion radiation with adaptive laboratory evolution, integrating heavy ion radiation with other mutagenic agents, adopting progressive radiation, formulating high-throughput screening schemes for mutants, and efficiently identifying, verifying, and integrating positive mutations. These strategies aim to improve the mutagenesis rate, screening efficiency, and utilization of positive mutations. Meanwhile, we envision a mutation breeding workstation that integrates a series of strategies to form a complete cycle for heavy-ion radiation-based mutation breeding. This study is expected to provide valuable insights for creating high-quality microbial resources through heavy-ion radiation.

Microorganisms in high-salt environments (including halophilic and halotolerant bacteria) are widely distributed in extreme habitats such as salt lakes, oceans, and saline soils. Due to their unique metabolic adaptation mechanisms, they have become an important source of structurally novel natural products. This article outlines their taxonomic status and ecological distribution, with a focus on summarizing the chemical structures of compatible solutes such as ectoine and glycine betaine among primary metabolites, and their core roles in osmotic pressure regulation and biomacromolecule protection. The structural types of secondary metabolites, including alkaloids, terpenoids, steroids, and polyketides, are systematically reviewed. Furthermore, this article summarizes the biological activities such as antibacterial, antitumor, antioxidant, enzyme inhibitory, and photoprotective effects and discusses the structure-activity relationships of secondary metabolites. Considering the unique properties of these metabolites, this article analyzes their application prospects in fields such as medicine and health, biomaterials, and environmental remediation. This review aims to provide a theoretical reference for the in-depth development of microbial resources in high-salt environments and the discovery of novel bioactive molecules.

Quorum sensing (QS) is a communication mechanism through which microorganisms secrete and sense signal molecules to regulate mircobial population behaviors. QS plays important roles in biofilm formation and gut colonization of probiotics. In recent years, interfering with the QS of probiotics has become a trending research field of synthetic biology. In this review, we summarize the distribution of QS systems in probiotics and highlights interfering strategies designed to regulate probiotic functions. We summary currently identified QS systems in probiotics and their detection methods, such as photoelectrochemical assays and chromatography-mass spectrometry techniques. Meanwhile, this review outlines the QS interfering approaches for probiotics, including the use of QS agonists and the optimization of related metabolic pathways. Finally, the probiotic intervention strategy targeting QS is proposed in this paper, providing a novel approach for regulating the efficacy of engineered probiotics, which is of great significance for the development and improvement of probiotic functional foods.

Objective To elucidate the diversity and community composition of endophytic and rhizospheric bacteria associated with Apocynum venetum in northern Xinjiang and to screen the strains with efficient and specific degumming potential. Methods Samples of A. venetum were collected from four regions: Karamay, Fukang, Urumqi, and Turpan. The bacterial community structure was analyzed by 16S rRNA gene high-throughput sequencing. Pure-culture techniques were employed for strain isolation, and functional strains exhibiting xylanase and pectinase activities but lacking cellulase activity were screened by Congo red staining and enzyme activity assays. Results High-throughput sequencing identified 872 genera of bacteria belonging to 345 families of 38 phyla, among which Pseudomonadota and Actinomycetota were the dominant phyla. Bacterial abundance and diversity followed the order: rhizospheric soil>root>leaf>stem. Microbial abundance and diversity at the Turpan site were lower than those at the other sampling sites. A total of 361 bacterial strains were isolated in pure culture, belonging to 86 genera, 47 families of 4 phyla. Nine specific degumming strains were screened out, of which seven (77.78%) strains were endophytes derived from stems and leaves. The optimal functional strain, Bacillus rugosus (VFS.M1.04), showed xylanase and pectinase activities of 2 237 U/mL and 1 002 U/mL, respectively. Conclusion The community structures of endophytic and rhizospheric bacteria associated with A. venetum are significantly influenced by habitats and plant parts. Bacillus is the dominant functional genus, and the homologous screening strategy effectively enables the acquisition of elite strains with strong degumming capacity and no cellulose degradation from stem and leaf endophytes. This study provides valuable microbial resources and a theoretical basis for developing a green biological degumming process for A. venetum. These findings support the targeted exploitation of plant-associated microbial strains for sustainable fiber processing.

Objective To systematically investigate the diversity of culturable yeasts in extreme environments (glaciers, salt lakes, deserts, etc.) of western China and explore yeast resources with special stress resistance traits. Methods Multiple substrate samples were collected from representative extreme environments. Eight media with different nutrient gradients were employed in combination with direct dilution plating and enrichment culture methods for yeast isolation. Strains were identified by 26S rDNA D1/D2 region sequence analysis. Multivariate statistical analysis was carried out to assess species diversity and community structure differences across habitats and culture methods. Results A total of 904 yeast strains were isolated, representing 77 species, 29 genera, 17 orders, 10 classes, 5 subphyla, and 2 phyla, including 11 potential new species. Basidiomycota was the dominant phylum (90.5%), and Naganishia, Rhodotorula, and Cystobasidium were the dominant genera. Distinct dominant species were observed among different habitats. Naganishia adeliensis and Naganishia albida were widely distributed across all investigated extreme environments, indicating strong broad-spectrum environmental adaptability. Rhodotorula mucilaginosa and Cystobasidium slooffiae were dominant species in glaciers and salt lakes. In addition, enrichment culture and oligotrophic media significantly improved the isolation efficiency of rare species. Conclusion Extreme environments in western China harbor remarkably rich yeast resources. While different extreme environments select for unique dominant groups, certain broadly adaptable polyextremophilic species are shared across environments. Extreme environments serve not only as a reservoir of new species but also potentially as an environmental reservoir for opportunistic pathogenic yeasts.

Objective To characterize the cultivable bacterial diversity patterns and extracellular enzyme-producing capacity in mangrove sediments from the Zhangjiang Estuary, with a particular focus on the distribution of dominant Bacillus sensu lato and the environmental factors shaping their assemblages. Methods Bacterial isolates were obtained by dilution plating. Taxonomic identification was performed by 16S rRNA gene sequencing. Plate-based assays were used to evaluate the activities of eight extracellular enzymes. Results In total, 1 392 isolates were obtained, representing 97 genera of 4 phyla. Bacillus sensu lato constituted the dominant assemblage (57.8%). Preliminary screening suggested 263 isolates (18.9%) as putative novel taxa, largely concentrated in Bacillus and allied genera such as Halobacillus. The Shannon diversity of cultivable bacteria was higher in the core mangrove zone and at the estuarine outlet than at the inlet (P<0.05), and the community composition differed among sites (P<0.05), being mainly associated with salinity and metal ions. By contrast, the community structure of Bacillus sensu lato was comparatively stable across space and was primarily associated with pH and carbon-nitrogen nutrient variables. Enzyme screening showed the highest positive rates for proteases (64.2%) and lipases (52.6%). Isolates affiliated with Bacillus sensu lato displayed higher positive rates than the overall community across multiple enzymes, indicating broad metabolic potential. Conclusion Mangrove sediments from the Zhangjiang Estuary harbor abundant cultivable bacterial resources. In addition to the dominant Bacillus-related taxa, Pseudomonadota and Bacteroidota appear to be key components underpinning overall community diversity. The high ecological stability and multi-substrate degradation capacity of Bacillus sensu lato, together with other bacterial groups, contribute to element cycling in mangrove sediments.

Objective The saline-alkaline habitats in Xinjiang harbor rich and unique microbial resources. This study employed the culture-dependent way to explore the culturable microbial resources and reveal their diversity and potential functions from seven different saline-alkaline habitats, including Barkol Lake and Aiding Lake in Xinjiang. Methods Soil and sediment samples were collected from the seven saline-alkaline habitats. Thirteen modified media were designed and used for strain isolation via the gradient dilution plating method. The 16S rRNA gene sequencing, phylogenetic analysis, and multi-condition culture were employed to analyze the taxonomic positions, suitable media, and salinity adaptability of the strains. Furthermore, potential novel taxa, anaerobic strains, and exopolysaccharide (EPS)-producing strains were screened. Results A total of 935 bacterial strains were isolated and identified as 310 species belonging to 125 genera, 54 families, 25 orders, 8 classes of 4 phyla, including 20 strains representing 15 potential novel taxa. The dominant culturable taxa were Bacillota, Pseudomonadota, and Actinomycetota. In addition, 52 strains (20 species) of anaerobic bacteria were obtained, with the genus Halomonas being dominant. The microbial resources varied significantly among different media, and R2A was the most effective medium, screening out 108 species. Bacillus was dominant under no salt stress (0 NaCl), and Marinobacter was one of the important genera under moderate salt stress (5% NaCl). However, the genus Halomonas kept being dominant under low-salt (0 NaCl), moderate-salt (5% NaCl), or high-salt (10% NaCl) stress. To obtain the functional strains with extremely strong stress resistance, we screened 15 EPS-producing strains under high-salt and high-alkali conditions. Among them, Marivirga harenae EGI S10258 and Halomonas alkaliantarctica EGI S10283 showed the highest EPS titer, which reached 4.5 g/L. Conclusion The saline-alkaline habitats in Xinjiang were rich with culturable microbial resources. The application of a multi-condition culture approach significantly enhances the depth and breadth of microbial resource exploration. This study provides important microbial resources and data support for subsequent research on systematic taxonomy, ecological adaptation mechanisms, and resource utilization by getting potential novel species and functional strains.

Objective To address problems such as the poor structure and fertility degradation in strongly acidic soils, we isolated acid-tolerant exopolysaccharide (EPS)-producing microorganisms, constructed a composite microbial inoculant, and evaluated its improvement effects on the structure and comprehensive fertility of acidic soils. Methods Target strains were obtained through primary and secondary screening from strongly acidic soils (pH<4.5) in Nanchuan, Chongqing and Qujing, Yunnan. After their antagonistic activity and plant growth-promoting traits were assessed, a composite microbial inoculant was constructed. A laboratory soil culture experiment was conducted to investigate changes in nutrient contents and aggregate composition in strongly acidic soils treated with different inoculants, comprehensively evaluate the fertility-improving effects of the inoculants, and clarify the correlation between aggregate formation and EPS content. Results Three strains—Paraburkholderia fungorum C3, Burkholderia cepacia A13, and Cystobasidium minutum B14—with acid tolerance and high EPS-producing capabilities were successfully isolated and screened out. All the strains exhibited the capabilities of secreting indole-3-acetic acid (IAA), synthesizing siderophores, and solubilizing phosphorus. When these strains were applied individually or as a composite inoculant to soils, the composite inoculant showed the best effect of improving soil nutrients, increasing the content of soil organic matter, alkaline-hydrolyzable nitrogen, available phosphorus, and available potassium by 4.51%, 13.92%, 4.92%, and 3.71%, respectively. Application of all the inoculants effectively promoted the formation of soil macro-aggregates, among which the single-strain inoculant C3 had the most significant effect in promoting aggregate formation, increasing the soil mean weight diameter (MWD) by 19.39%. The integrated fertility index of the soil treated with the composite inoculant reached 0.61, indicating the optimal comprehensive improvement effect. The single-strain inoculant C3 and the composite inoculant significantly increased the soil EPS content by 53.17% and 35.79%, respectively. Correlation analysis results showed that soil EPS had significantly positive correlations with macro-aggregate content and MWD, significantly promoting the formation and enhancing the stability of soil macro-aggregates. Conclusion The composite inoculant composed of the three acid-tolerant EPS-producing strains screened in this study effectively improved the soil structure and enhanced the integrated soil fertility. These findings lay a theoretical foundation for the development of biological agents for acidic soil remediation.

Fusarium proliferatum is a critical pathogenic fungus causing soybean root rot. A halotolerant biocontrol strain Bacillus sp. YH7-4 was isolated from the Yuncheng Salt Lake. Objective To investigate strain YH7-4 in terms of the effect on soybean growth and the control efficacy against soybean root rot. Additionally, we sought to elucidate the antifungal mechanisms of this strain and identify antimicrobial genes through whole genome sequencing. Methods The plate dual-culture method was adopted to assess the antifungal activity of strain YH7-4. Pot experiments were conducted to evaluate the safety of the strain to soybean seedlings and the control efficacy against root rot. Illumina and PacBio platforms were used for whole genome sequencing of YH7-4. Subsequent analyses included metabolic system assessment, virulence factor prediction, transporter analysis, identification of genes related to biocontrol functions, comparative genomics, and biochemical assays. Results Strain YH7-4 demonstrated the inhibition rates exceeding 75.00% against several plant pathogens, including F. proliferatum, Phytophthora sojae, Colletotrichum truncatum, and Phomopsis longicolla. Pot experiments showed that at the OD₆₀₀ value of 0.8, YH7-4 suspension significantly increased the root length and dry weight of soybean seedlings, while excessively high concentrations abolished this effect. The control efficacy of YH7-4 against F. proliferatum-induced soybean root rot reached 56.02%. Whole genome sequencing revealed a genome of 3 945 352 bp with the G+C content of 46.51% and 3 756 predicted coding genes. These genes were annotated against databases including NR, Swiss-Prot, Pfam, COG, GO, and KEGG, with 3 753, 3 537, 3 358, 3 082, 1 756, and 2 845 sequences successfully annotated, respectively. Among the proteins encoded by these genes, 130 proteins belonged to the CAZy family. Twelve secondary metabolite biosynthetic gene clusters were identified, including eight known biosynthetic gene clusters for antibiotics (surfactin, macrolactin H, bacillaene, fengycin, difficidin, bacillibactin, bacilysin, and butirosin A/butirosin B) and four gene clusters with unknown functions. Additionally, two siderophore-related genes, one gene encoding 2,3-butanediol (associated with induced systemic resistance), and 15 genes involved in biofilm formation were identified. Comparative genomics analysis indicated that YH7-4 was a strain of Bacillus velezensis and shared 2 898 orthologous core gene clusters. Biochemical characterization showed that YH7-4 had the ability to produce amylase, protease, pectinase, and cellulase. Conclusion The halotolerant strain B. velezensis YH7-4 isolated from the Yuncheng Salt Lake shows excellent control efficacy against soybean root rot. Its genome harbors genes linked to biocontrol traits and antimicrobial substance production, which makes this strain a promising candidate for managing soybean root rot and other plant fungal diseases. This study applies salt lake-derived bacteria to plant roots, demonstrating their influence on soybean growth while providing a theoretical basis for further elucidating the antifungal mechanisms of B. velezensis YH7-4.

Para-ethoxyaniline (ETH), a widely used industrial raw material and intermediate, persists in the environment, posing potential risks to ecosystems and human health. Objective To isolate an efficient ETH-degrading strain from activated sludge, optimize its degradation conditions, and elucidate the gene regulatory mechanisms and metabolic pathways under ETH stress by transcriptomic and mass spectrometric analyses. Methods A strain capable of utilizing ETH as the sole carbon source was isolated from activated sludge and identified through morphological observation, physiological and biochemical tests, and phylogenetic tree construction based on 16S rRNA gene sequences. The effects of temperature, pH, and initial ETH concentration on bacterial growth and degradation efficiency were examined. Transcriptome sequencing was employed to identify differentially expressed genes (DEGs), with selected up-regulated DEGs validated by real-time reverse transcription quantitative (RT-qPCR). Furthermore, mass spectrometry was employed to investigate the metabolic pathways. Results A highly efficient ETH-degrading strain, designated DQ78 and identified as Pseudomonas sp., was isolated. Under optimal conditions (28 ℃, pH 8.0, 4 mmol/L ETH, and 1% inoculum), it completely degraded ETH within 40 h. Three metabolic intermediates were identified, allowing the proposal of a preliminary degradation pathway. Transcriptomic analysis revealed 3 380 DEGs under ETH stress, including 1 609 up-regulated and 1 771 down-regulated genes. GO enrichment indicated up-regulated genes were primarily involved in 57 GO terms such as amino acid metabolism, cell motility, iron binding, and transport, which might activate the synthesis of ETF-degrading enzymes and enhance substrate uptake and transmembrane metabolism of intermediates. The down-regulated genes were enriched in 58 GO terms such as peptide metabolism and synthesis, ribosomal structure, and cellular components, suggesting a metabolic reallocation toward stress adaptation. KEGG analysis predicted 183 up-regulated pathways and 184 down-regulated pathways such as flagellar assembly, sulfur metabolism, and extracellular biosynthesis under ETH stress, indicating enhanced chemotaxis, enzyme secretion, and stress-resistant substance synthesis. Conclusion Strain DQ78 achieved complete degradation of ETH within 40 h, being a promising candidate for the bioremediation of ETH-contaminated environments. Transcriptomic analysis reveals the molecular regulatory mechanism of this strain in response to ETH, which lays a theoretical foundation for further exploring the genetic foundation of microbial degradation of organic pollutants.

Litchi (Litchi chinensis Sonn.) is one of the important tropical and subtropical fruits in China. However, litchi downy blight caused by the infection of Peronophythora litchii (Peronophythora litchii Chen ex Ko et al.) a severe disease damaging litchi during production, storage, and transportation, seriously threatening the healthy development of China’s litchi industry. Objective We screened effective antagonistic bacteria against P. litchii and evaluated their plant growth-promoting potential, aiming to enrich the resources of antagonistic bacteria against P. litchii. Methods Soil samples from the litchi rhizosphere were collected, and the bacteria in the samples were isolated through a high-throughput isolation and culture method. The strains were identified by means of 16S rRNA gene sequence analysis. The antagonistic strains against P. litchii were screened via the plate confrontation method, and the plant growth-promoting functions [phosphorus solubilization, potassium solubilization, nitrogen fixation, siderophore secretion, and indole-3-acetic acid (IAA) production] of the antagonistic strains were further evaluated through functional plates. Results A total of 327 bacterial strains were isolated in this study, among which 92 (28.13%) strains were identified as antagonists (with mycelial growth inhibition rates>40%) against P. litchii. These antagonistic strains belonged to 4 phyla, 6 classes, 12 orders, 20 families, and 42 genera, with Bacillota and Pseudomonadota being the dominant phyla, and Bacillus and Paenibacillus as the dominant genera. Functional evaluation of the 92 antagonistic strains revealed that 55 (59.8%) strains exhibited more than one plant growth-promoting function, while 30 (32.6%) strains possessed three or more such functions. Through comprehensive evaluation of antagonistic activity and plant growth-promoting functions, one Brevibacillus strain T101, four Paenibacillus strains (T431, T270, T327, and T234a), and one Paraburkholderia strain R116b were identified as the most promising strains for biocontrol applications. Conclusion Multiple antagonistic strains against P. litchi,with functions of phosphorus solubilization, potassium solubilization, nitrogen fixation, siderophore secretion, and IAA production, are screened out, which provides efficient strain resources for the green control of litchi downy blight.

Objective To identify high-quality yeast strains in the Xinjiang traditional milk wine fermentation system and screen specialized strains suitable for the milk wine fermentation, thereby providing a theoretical basis and strain reserves for the development of dedicated fermentation agents. Methods With alcohol production, ester production, lactose utilization ability, as well as acid (pH), glucose, and ethanol tolerance as screening criteria, the gradient dilution separation method combined with selective media was employed to isolate yeast strains. Morphological observation and molecular biological identification were conducted to determine the taxonomic status of the strains. The growth characteristics, carbon source utilization ability, and biosafety of the strains were investigated. The fermentation flavor contributions of the strains were evaluated through sensory assessment and electronic nose technology. Results Forty yeast strains were isolated and purified from Xinjiang traditional milk wine starter and traditional fermented dairy products. After multiple rounds of screening, two strains (J17 and J23) with excellent functions were obtained, tolerating pH 2.5, 350 g/L glucose, and 47.34 g/L ethanol. They were identified as Kluyveromyces marxianus and Pichia kudriavzevii,respectively. The growth curves of the two strains showed that the logarithmic phase began at the time point of 4 h and the stationary phase started at 12 h and 18 h, respectively. The co-culture test confirmed no antagonistic effects and demonstrated symbiotic relationships between the two strains. Carbon source utilization tests indicated that both strains efficiently utilized seven carbon sources, including glucose, lactose, and sucrose, demonstrating strong metabolic adaptability. Biosafety testing revealed that neither strain exhibited hemolytic activity and was sensitive to antifungal drugs such as ketoconazole, meeting the safety standards for food fermentation strains. Electronic nose analysis revealed that the 1:1 mixed strain (HJ) fermentation of milk wine substrate exhibited significantly higher response values for flavor compounds such as alkanes, sulfides, alcohols, and aldehydes/ketones than the single-strain fermentation groups and controls. Both the cumulative contribution rate of PCA and the cumulative discriminant rate of LDA reached 99.97%. Sensory assessment demonstrated that the HJ fermented milk wine scored higher than that of other strain combinations in four dimensions: appearance, aroma, taste, and style. Conclusion K. marxianus J17 and P. kudriavzevii J23 demonstrate high tolerance, broad-spectrum carbon source utilization ability, excellent biosafety, and synergistic aroma enhancement, showing the potential as specialized fermentation agents for milk wine production and providing high-quality microbial resources for the fermentation of traditional milk wine.

Kitchen waste contains recalcitrant lipids that are prone to rancidification and can cause environmental pollution. Objective To isolate efficient lipase-producing strains from kitchen waste, optimize their enzyme production conditions, and evaluate the lipid-degrading potential of their extracellular products in kitchen waste. Methods Lipase-producing strains were isolated from canteen swill via the neutral red medium and identified based on morphological characteristics and 16S rRNA gene sequences. Lipase production conditions were optimized through single-factor experiments and response surface methodology. The properties of the lipase and the emulsification performance of extracellular polymeric substances (EPS) were analyzed. Results A strain designated C24202, exhibiting strong lipase- and biosurfactant-producing activity, was isolated and identified as Stenotrophomonas maltophilia. The fermentation conditions were optimized as follows: lactose 10.0 g/L, yeast extract 7.5 g/L, emulsified soybean oil 40.0 g/L, FeSO₄ 8.0 g/L, and incubation at 34 ℃ and initial pH 6.5 for 72 h. Under these conditions, the lipase activity reached (229.64±2.17) U/mL, representing a 2.55-fold increase compared with the pre-optimization level. The lipase exhibited an optimal temperature of 60 ℃ and retained 50.70% of its activity after incubation at 50 ℃ for 6 h, demonstrating good thermal stability. The EPS produced by strain C24202 showed strong emulsifying capacity, with an EI₂₄ value of 46.92%. FTIR analysis suggested that the EPS may be polymeric glycolipopeptide-type biosurfactants. Conclusion Strain C24202 possesses dual capabilities of producing thermostable lipase and biosurfactants, demonstrating promising potential for lipid degradation and the treatment of oil-containing wastewater.

Objective To explore microbial resources suitable for the ecological restoration of saline-alkaline soils and elucidate their stress tolerance and plant growth-promoting traits, thereby providing a theoretical basis for biotechnology-driven sustainable agricultural development. Methods Plant growth-promoting rhizobacteria (PGPR) were isolated and screened from the rhizosphere soils of three representative halophytes—Tamarix ramosissima, Lycium ruthenicum, and Kalidium foliatum—growing in the Minqin Oasis, Gansu Province, northwestern China. Selected strains were taxonomically identified by 16S rRNA gene sequence analysis. Their functional traits were systematically evaluated, including nitrogen fixation, phosphate solubilization, and production of indole-3-acetic acid (IAA), exopolysaccharides (EPS), and siderophores. In addition, stress tolerance under salinity, drought, pH, and temperature gradients, as well as antagonistic activity against six common phytopathogenic fungi, was assessed. Results A total of 62 bacterial isolates were obtained, among which seven multifunctional PGPR strains (HL3, HL6, HL12, HG3, HG8, HG12, and HG24) were selected and identified as Priestia filamentosa, Bacillus atrophaeus, Pantoea endophytica, Peribacillus frigoritolerans, Bacillus aryabhattai, Bacillus subtilis subsp. stercoris,and Paenibacillus peoriae, respectively. All the selected strains exhibited at least two plant growth-promoting traits. Notably, strains HL6 and HG24 simultaneously possessed nitrogen-fixing ability, phosphate-solubilizing capacity, and the ability to produce IAA, EPS and siderophores, showcasing pronounced multifunctionality. Stress tolerance assays showed that strains HL3 and HL6 tolerated up to 12% NaCl, while HL3 and HG8 withstood osmotic stress equivalent to -20 bar. Most strains remained active under alkaline conditions (pH 9.0) and within a temperature range of 28-45 ℃. Antagonistic assays revealed that HL6 inhibited all six tested phytopathogenic fungi, and HG24 exhibited broad-spectrum antagonistic activity against five pathogens, with the strongest inhibition observed against Alternaria solani. Conclusion This study demonstrates that PGPR isolated from the rhizosphere of halophytes in arid regions possess diverse plant growth-promoting functions and strong stress tolerance. These multifunctional and resilient strains represent valuable microbial resources for saline-alkaline soil remediation and the development of locally adapted biofertilizers, contributing to sustainable agriculture and ecological restoration in arid environments.

Objective To isolate and characterize plant growth-promoting rhizobacteria (PGPR) from the roots of the rice variety YTZ and the backcross progeny H8 with tolerance to low nitrogen and low phosphorus, and evaluate the potential of PGPR in promoting the growth of rice seedlings. Methods Bacterial strains were isolated by plate streaking and taxonomically identified through 16S rRNA gene sequencing. Functional traits, including phosphate solubilization, nitrogen fixation, and indole-3-acetic acid (IAA) production, were assessed for strain selection. Whole-genome sequencing was performed to mine functional genes and elucidate potential molecular mechanisms of target strains. Pot experiments were conducted to evaluate strain effects on the physicochemical properties of soil and nutrient (nitrogen and phosphorus) uptake of seedlings, while 16S rRNA gene amplicon sequencing was employed to analyze rhizosphere microbial community dynamics. In addition, synthetic microbial consortia and carrier combinations were developed and assessed for application feasibility. Results Seven strains with phosphate-solubilizing and nitrogen-fixing capabilities were obtained, and their IAA production was quantitatively determined. Five representative strains were selected for pot experiments. Among them, B. altitudinis Hxx04 exhibited the strongest plant growth-promoting effect, increasing the fresh weight by 47.2% and plant height by 48.6%, while significantly enhancing nitrogen and phosphorus uptake efficiency of rice seedlings. Inoculation with Hxx04 led to marked reductions in soil total nitrogen, alkali-hydrolyzable nitrogen, total phosphorus, and available phosphorus, indicating improved nutrient uptake by rice plants. Rhizosphere community analysis revealed increased microbial abundance following inoculation, which supported the nitrogen supply for seedling growth. Furthermore, a synthetic microbial consortium centered on B. altitudinis Hxx04 performed optimally when being inoculated with the carrier combination of bentonite and straw. Conclusion B. altitudinis Hxx04 demonstrated high efficiency in nitrogen and phosphorus utilization and significantly promoted rice growth (evidenced by increased fresh weight and plant height), thereby reducing chemical fertilizer dependence. Its dual contribution to yield enhancement and environmental sustainability highlights its potential as a valuable microbial resource for green agriculture, supporting the goal of coordinating nutrient use efficiency with ecological conservation in rice production.

Objective To screen the microbial strains producing volatile organic compounds (VOCs) with both broad-spectrum antagonistic activity and postharvest fruit preservation potential. Methods Endophytic bacterial strains were isolated and purified by the dilution plating method from the roots and branches of wild tea plants in Guangxi, China. Candidate strains were initially selected based on the number of functional traits via six types of functional media: cellulase, amylase, siderophore, organic phosphorus, inorganic phosphorus, and nitrogen-fixing media. The antagonistic activity of the strains against seven common plant pathogenic fungi was determined by the dual-culture assay, and thus the broad-spectrum antagonistic strains were screened out. Strains with superior overall performance were further selected to evaluate their antagonistic activity against the postharvest anthracnose pathogens—Colletotrichum fructicola and Colletotrichum musae—of mangoes and bananas. An in vitro banana preservation assay was conducted with the chemical preservative prochloraz as a positive control. Results Functional screening on selective media yielded 98 strains that simultaneously possessed four or more plant growth-promoting or stress-tolerance traits, including nitrogen fixation, phosphate solubilization, and siderophore production. In dual-culture assays against seven common plant pathogenic fungi, 18 broad-spectrum antagonistic strains significantly inhibiting at least five pathogens were screened out, among which four strains exhibited stable and strong antagonistic activity against all the seven pathogens. On this basis, two key indicators, number of functional traits and broad-spectrum inhibition rate, were comprehensively evaluated, and five strains with the best overall performance were finally selected for subsequent specific antagonism assays against the pathogens causing mango and banana anthracnose and for validation of their postharvest fruit preservation effects. In dual-culture assays, the inhibition rates of the tested strains against the two anthracnose pathogens ranged from 43.36% to 83.50%. In plate-on-plate assays, the VOCs produced by these strains exhibited inhibition rates of 56.80%-99.25% against C. fructicola and 54.50%-99.85% against C. musae, with several strains showing nearly 100.00% inhibitory activity against both pathogens. In vitro fruit preservation tests demonstrated that VOCs produced by the antagonistic strains delayed the postharvest decay of mangoes and bananas to varying degrees. Strain T-1-6 showed the most pronounced effect, extending the onset of visible banana decay to 21 days (the final decay grade was grade 0), and its preservation effect was comparable to that of the chemical preservative prochloraz, achieving approximately 50% control efficacy against surface molds on mangoes. Analysis of 16S rRNA gene and gyrB sequences revealed that all the five dominant antagonistic strains belonged to the genus Bacillus, including B. amyloliquefaciens, B. thuringiensis, B. cereus, and B. subtilis. Conclusion The VOCs-producing endophytic Bacillus strains from tea plants possess multiple functional traits and broad-spectrum antagonistic activity. This study provides promising candidate strains and a theoretical basis for the green disease control and biopreservation of postharvest tropical fruits such as mangoes and bananas.

Soil nutrient deficiency is a major limiting factor affecting crop yields. Excessive use of chemical fertilizers can lead to soil compaction, environmental pollution, and decreased crop yields and quality. Microalgae-based fertilizer, functioning as a novel green bio-fertilizer, not only effectively promotes crop growth but also enhances soil fertility under various adverse soil conditions. Objectives This study investigated the effects of different fertilizer treatments on the growth of foxtail millet (Setaria italica L.) and the physicochemical properties, enzymes activities, and microbial communities of infertile soil, aiming to provide theoretical support for the application of microalgae-based fertilizer in chemical fertilizer reduction and green sustainable agricultural production. Methods The foxtail millet cultivar ‘Jingu 21’ was cultivated in this study under five fertilizer treatments: full chemical fertilizer (T1), chemical-microalgae integrated fertilizer (T2: 80% chemical fertilizer+20% microalgae-based fertilizer; T3: 60% chemical fertilizer+40% microalgae-based fertilizer; T4: 40% chemical fertilizer+60% microalgae-based fertilizer), and full microalgae-based fertilizer (T5). The growth indexes, biomass, and pigment content of foxtail millet in each treatment were determined, and the physicochemical properties, enzyme activities, and bacterial community characteristics of the infertile soil were measured, after 90 days of cultivation. Results Among the five fertilizer treatments, T4 had the most significant effect of promoting the seedling growth of foxtail millet in the infertile soil. Compared with T1, T4 increased the seedling height, the aboveground dry weight, and the content of chlorophyll a, chlorophyll b, and carotenoids by 26.41%, 126.47%, 17.1%, 24.5%, and 28.0%, respectively. In addition, T5, T2, T3, and T4 increased the content of total nitrogen, available phosphorus, and organic matter and the activities of sucrase, nitrate reductase, peroxidase, and phosphatase in the soil, compared with T1, and T4 had the most significant soil improvement effect. The 16S rRNA gene amplicon sequencing results showed that compared with T1 and T5, T4 increased the diversity of soil microorganisms, in which the relative abundance of Acidobacteriota and Chloroflexi was significantly increased. The correlation analysis showed that the composition of soil microbial diversity was significantly and positively correlated with urease, and the soil microbial community composition had significantly positive correlations with available phosphorus, sucrase, peroxidase, and urease. Redundancy analysis showed that urease and available phosphorus were the main environmental factors affecting the soil bacterial community structure. The relative abundance of Chloroflexi had significantly positive correlations with the urease activity and the available phosphorus content. Conclusion The combined application of microalgae-based fertilizer with reduced chemical fertilizer not only effectively improves the nutrient content and enzyme activities but also enhances the microbial diversity and community structure in the soil, thereby promoting the growth of foxtail millet seedlings in infertile soil.

Objective To investigate the growth-promoting properties and mechanisms of Bacillus amyloliquefaciens DGL1 isolated from arid sandy soils of the Qinghai-Xizang Plateau on oat plants under drought stress, thus providing a high-quality microbial resource and a theoretical basis for developing microbial fertilizers suitable for arid regions. Methods The growth-promoting effects of strain DGL1 on oat root length, plant height, and fresh weight under drought stress were determined. The degree of cell membrane lipid peroxidation and the activities of antioxidant enzymes in oat plants under drought stress were measured. The genome and transcriptome of strain DGL1 were sequenced via high-throughput technology. Results Strain DGL1 significantly increased the root length, plant height, and fresh weight of oat plants under drought stress. It markedly elevated the activities of antioxidant enzymes [(superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)] while reducing the content of malondialdehyde and H₂O₂. Genomic analysis revealed that DGL1 carried the genes related to oxidative stress (gpx encoding glutathione peroxidase, opuD encoding glycine-betaine transporter, and ahpF encoding alkyl hydroperoxide reductase), synthesis of the IAA precursor l-tryptophan (trpA, trpB, and trpC), and flagellar biosynthesis (FliP, FliQ, and FliR). Transcriptome sequencing further revealed that genes associated with biofilm formation, nitrogen and phosphorus uptake, material and energy metabolism, and auxin precursor synthesis—all crucial for root colonization—presented upregulated expression under drought stress. The strain might enhance plant drought tolerance via these pathways. Conclusion Strain DGL1 can enhance the drought tolerance of oat plants and has great potential for application in developing bio-inoculants for arid land agriculture.

As a pioneer species in desert areas and the main host of Cistanche deserticola, Atriplex canescens is widely planted in the Ulan Buh Desert in Inner Mongolia. Rhizosphere and endophytic microorganisms play a significant role in the growth and stress resistance of plants. However, few studies have been conducted on the growth-promoting functions of rhizosphere and endophytic bacteria on A. canescens in the Ulan Buh Desert. Objective We screened plant growth-promoting strains from the rhizosphere and endophytic bacteria of A. canescens, aiming to provide microbial resources for the sustainable breeding of A. canescens in this region. Methods Rhizosphere soil and plant samples of A. canescens were collected from the Ulan Buh Desert in Dengkou County, Inner Mongolia. Rhizosphere and endophytic bacteria were isolated and purified. The plant growth-promoting effects of these bacteria and the plant growth-promoting bacteria of Astragalus previously obtained by our research group on A. canescens seedlings were investigated. Molecular biological identification and functional analysis were conducted on the strains with significant plant growth-promoting effects. Then, these strains were combined and the growth-promoting effects of the strain combinations on A. canescens were evaluated. Results A total of 60 rhizosphere bacterial strains and 14 endophytic bacterial strains of A. canescens were isolated. Two endophytic bacterial strains significantly promoted the growth of A. canescens seedlings. Among the Astragalus growth-promoting bacteria tested, three strains had significant growth-promoting effects on A. canescens seedlings. The five plant growth-promoting strains were identified as four species belonging to three genera: Pseudomonas, Bacillus, and Acinetobacter. These strains had different levels of nitrogen fixation, inorganic and organic phosphorus solubilization, potassium feldspar and potassium aluminum silicate solubilization, and indole-3-acetic acid (IAA) and biofilm production. Most of the strains had the ability to produce siderophores. Multiple strain combinations promoted the growth of A. canescens. Combinations 2 (IH-2, IH-9, and TYA27), 3 (IH-2, IH-9, and PAS13-2) and 4 (IH-2, TYA39, and TYA27) demonstrated the best comprehensive plant growth-promoting effects, with Pseudomonas bijieensis IH-2 as the core strain. Conclusion The growth-promoting bacteria of A. canescens in the Ulan Buh Desert mainly include Pseudomonas and Bacillus. P. bijieensis plays a core role in the plant growth-promoting bacterial combinations.

Objective To explore the nitrogen and phosphorus removal efficiency of different immobilization strategies and mineralization methods of Bacillus licheniformis ZXT for high nitrogen-phosphorus wastewater, clarify the optimal mineralization conditions and carrier mechanism of action, and provide technical support for the green treatment and recovery of complex high nitrogen-phosphorus wastewater resources such as swine manure wastewater. Methods Four systems—free bacteria, chemical precipitation, activated carbon fiber (ACF) immobilization, and polyvinyl alcohol-sodium alginate-carbon powder (PVA-SA-CP) immobilization—were compared for their mineralization effects under Mg:N:P molar ratios of 0.6:1:1, 1:1:1, and 1.4:1:1. Characterization techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR) were employed to analyze mineral properties. The application potential of the systems was verified with actual swine manure wastewater. Results The ACF immobilization system exhibited the optimal efficiency. Under the Mg:N:P ratio of 1:1:1, after seven days of cultivation, the final concentration of NH₄⁺ was only 0.59 mg/L (removal rate: 99.81%) and the final concentration of PO₄^3- was as low as 0.03 mg/L (removal rate: 99.99%), both meeting the national discharge standards (GB 8978—1996), with the formation of regular crystalline long plate-like struvite (i.e., magnesium ammonium phosphate, MAP). The PVA-SA-CP immobilization system showed significantly weaker removal effects under the same ratio, with final concentrations of NH₄⁺ and PO₄^3- being 5.07 mg/L and 0.45 mg/L, respectively. The chemical precipitation method failed to meet the standards, as the final concentration of NH₄⁺ ranged from 38.90 to 48.01 mg/L (removal rate: 84.70%-87.61%) within 24 h. Free bacteria achieved the removal rates of 99.97% for NH₄⁺ and 99.92% for PO₄^3- in actual swine manure wastewater after eight days of cultivation, with final NH₄⁺ and PO₄^3- concentrations of 0.15 mg/L and 0.05 mg/L, respectively, which complied with the discharge requirements. Conclusion Due to its developed microporous structure and good biocompatibility, ACF can efficiently enrich bacteria and promote the regular assembly of extracellular polymeric substances. The mineralization with ACF-immobilized B. licheniformis ZXT is the optimal choice, with Mg:N:P=1:1:1 as the best mineralization ratio. This technology can achieve efficient purification of high nitrogen-phosphorus wastewater and recovery of nitrogen and phosphorus resources, thus having important application value in actual wastewater treatment.

Objective The rhizosphere microbial community plays a critical role in plant growth, development, and quality formation. Therefore, this study systematically isolated plant growth-promoting microbial resources from the rhizosphere of Bupleurum chinense and evaluated their application potential, aiming to provide excellent strains for the development of microbial fertilizers to reduce the use of chemical fertilizers and pesticides. Methods Plant growth-promoting rhizobacteria (PGPR) and arbuscular mycorrhizal fungi (AMF) were isolated and identified from the rhizosphere of B. chinense by the culture-dependent methods. Functional traits of PGPR strains were screened through in vitro assays, and the synergistic growth-promoting effects of PGPR and AMF were subsequently evaluated by a pot experiment. Results A total of 25 PGPR species and 2 AMF species (Funneliformis mosseae and Entrophospora etunicata) were isolated from the rhizosphere of B. chinense. Functional screening of PGPR revealed that Lysobacter antibioticus, Pseudomonas germanica, Rhodococcus corynebacterioides, and Methylobacterium marchantiae exhibited outstanding abilities in indole-3-acetic acid production, organic phosphorus solubilization, inorganic phosphorus solubilization, and nitrogen fixation, respectively. The pot experiment showed that co-inoculation with PGPR and AMF significantly enhanced the plant growth, biomass accumulation, and nutrient uptake of B. chinense, with plant growth-promoting effects markedly greater than single inoculation treatments. Conclusion This study isolated and identified some plant growth-promoting microorganisms from the rhizosphere of B. chinense and demonstrated the synergistic effects between PGPR and AMF, providing valuable microbial resources and theoretical bases for the sustainable cultivation of B. chinense.

Objective Sebum metabolism disorders are a key contributing factor to various dermatological conditions. As an emerging class of microbial agents, postbiotics show potential in regulating metabolic processes. This study aimed to investigate the efficacy and mechanisms of Lacticaseibacillus paracasei CCFM1224 postbiotics in alleviating sebum metabolism disorders and explore the active components responsible for the effects. Methods Using a mouse model of oleic acid-induced sebum metabolism disorders, we comprehensively evaluated the efficacy of CCFM1224 postbiotics in ameliorating sebum imbalance. This evaluation encompassed phenotypic measurements, hormonal parameters, and skin lipid content. Changes in the expression of genes related to skin lipid metabolism were measured via real-time quantitative PCR. Subsequently, a free fatty acid-induced lipid accumulation model in HepG2 cells was utilized to screen the active components of postbiotics. Results CCFM1224 postbiotics significantly ameliorated sebum metabolism disorders in mice. This was evidenced by mitigated abnormal weight gain, a reduced testicle index, alleviated histopathological skin damage, and decreased levels of inflammatory cytokines (IL-6, IL-1β, and TNF-α) as well as triglyceride (TG) and non-esterified fatty acid (NEFA) in the skin tissue. CCFM1224 postbiotics modulated sebum metabolism by downregulating the expression of lipogenesis-related genes (FASN, PPAR-γ, and SREBP-1c) and upregulating the expression of lipolysis-related genes (PPAR-α, HSL, and ATGL). Further cellular validation identified the inactivated bacterial cell component as the key functional fraction, which effectively alleviated intracellular lipid accumulation and associated damage, thereby clarifying the material basis for the effects of CCFM1224 postbiotics. Conclusion L. paracasei CCFM1224 ameliorate sebum metabolism disorders by modulating hormone secretion and lipid metabolic pathways. The key bioactive components were identified as the inactivated bacterial cells, rather than the fermentation supernatant. This finding provides a theoretical foundation for the application of postbiotics in regulating lipid metabolism disorders and establishes a basis for developing related functional microbial preparations.

Objective To obtain microbial communities capable of degrading polystyrene microplastics (PS) and polypropylene microplastics (PP) and analyze their degradation efficiency and synergistic mechanisms, thus providing resources and theoretical support for the in-situ bioremediation and enriching our understanding of the mechanisms underlying the synergistic degradation of complex pollutants by microbial communities. Methods The microbial communities capable of degrading PS and PP were enriched from plastic-contaminated activated sludge of enterprises. A 60-day degradation experiment was carried out to evaluate the degradation efficiency of the microbial communities on the two microplastics based on the weight loss rate. The surface structures, hydrophobicity, and molecular weight changes of microplastics were characterized by scanning electron microscopy (SEM), water contact angle (WCA), and gel permeation chromatography (GPC). Fourier transform infrared spectroscopy (FTIR) and GC-MS were employed to analyze the degradation products and metabolic pathways of microplastics. The dominant groups, core functional bacteria, and their encoded related enzymes in the microbial communities were clarified through metagenomic analysis, on the basis of which the synergistic degradation mechanisms of the microbial communities were explored. Results The enriched microbial communities were dominated by Bacillota and Pseudomonadota. Bacillus initiated the initial degradation and Achromobacter participated in the intermediate metabolism, forming an “initiation-metabolism” synergistic network. PS and PP could be degraded without pretreatment within 60 days, with weight loss rates of (13.4±2.3)% and (23.2±2.4)%, respectively. Characterization confirmed that the microplastics during degradation presented damaged surfaces, reduced hydrophobicity, and decreased molecular weights. FTIR and GC-MS revealed that PS generated phenols and aldehydes through benzene ring hydroxylation and other processes, and entered the tricarboxylic acid cycle through the aromatic degradation pathway; PP were metabolized through the fatty acid degradation pathway via the oxidation chain of hydroxylation→carbonylation→esterification. The functional annotation of metagenomic data revealed that the genes encoding primary degradative enzymes and metabolic enzymes from Bacillus and Achromobacter exhibited complementary functions, forming the molecular basis for efficient degradation. Conclusion The microbial communities identified in this study efficiently degrade PS and PP. It is hypothesized that their core functional bacteria, Bacillus and Achromobacter, achieve degradation of both microplastics through a synergistic “initiation-metabolism” network and functionally complementary enzyme systems. This provides insights for managing residual microplastics after source control and deepens our understanding of the mechanisms underlying microbial synergistic degradation of complex pollutants.

Objective Chondroitinases are crucial enzymes for the preparation of low-molecular-weight chondroitin sulfate (CS), yet the existing enzymes are insufficient to meet the demands of diverse applications, highlighting the need to discover novel chondroitinases with enhanced properties. Methods A novel chondroitinase belonging to the polysaccharide lyase family 8 (PL8), designated SlChase, was discovered and identified from the model strain Streptomyces lividans TK24. Following heterologous expression in Escherichia coli and the subsequent purification, a soluble and highly active recombinant SlChase was successfully obtained. Results This enzyme exhibited substantial activity within the temperature range of 30-40 ℃ and pH range of 5.5-6.5, and demonstrated excellent long-term stability during storage at 4 ℃. Mg²⁺ and dithiothreitol (DTT) moderately enhanced its catalytic activity, whereas metal ions including Zn²⁺ and Fe³⁺ exerted inhibitory effects on its activity. Notably, SlChase displayed prominent activity towards unsulfated chondroitin (CS-0S), whereas its catalytic activity towards chondroitin sulfate A/C was drastically decreased. Conclusion The discovered SlChase not only expands the diversity of PL8 family enzymes but also affords a novel enzymatic tool for the specific degradation of unsulfated chondroitin, with promising applications in glycoscience research and related biocatalytic processes. Furthermore, this study provides a paradigm for the exploration and utilization of enzymatic resources derived from Streptomyces spp.

In recent decades, the extensive and inappropriate use of antibiotics has led to the emergence of antibiotic-resistant bacteria, posing a serious threat to human health. Phage therapy has emerged as a promising approach for preventing and treating infections caused by drug-resistant bacteria, garnering considerable research interest. However, the rapid development of phage-resistant bacterial strains complicates the effectiveness of phage therapy. The phage steering strategy holds promise for addressing this challenge. Objective To isolate virulent phages specific to Salmonella that are suitable for phage steering therapy. Methods Specific virulent phages for Salmonella S503 were isolated and purified from wastewater samples collected from a wet market via the double agar overlay method. Their fundamental biological characteristics, antibacterial efficacy, genomic information, and in vitro biological safety were analyzed. Phage-resistant strains were generated through co-culturing Salmonella S503 with the phages. Subsequently, growth curve analysis, bacterial virulence testing, and antibiotic sensitivity assays were employed to systematically compare the characteristics of the wild-type strain and its phage-resistant counterpart. Results The isolated Salmonella phage was designated HK-1. This phage exhibited strong antibacterial properties, high stability, and confirmed biological safety in vitro. Compared with the wild-type strain Salmonella S503, the phage-resistant strain Salmonella S503-R displayed slow growth, significantly reduced virulence, and increased susceptibility to 11 different antibiotics. Furthermore, phage HK-1 demonstrated synergistic bactericidal effects when being combined with rifampicin, ampicillin, fosfomycin, and gentamicin. Notably, the combinations of HK-1 with ampicillin, fosfomycin, and gentamicin effectively inhibited the growth of Salmonella S503 within 24 h. Conclusion We successfully isolated a virulent phage from wastewater samples. This phage is suitable for phage steering therapy and offers potential for the prevention and treatment of antibiotic-resistant Salmonella.

Objective To develop a fluorescence method for Vibrio parahaemolyticus detection by the combination of CRISPR system and the hybridization chain reaction (HCR), thus achieving rapid, sensitive, and accurate detection of the pathogen. Methods Cascade probe (RP/I) and HCR hairpin structures were first designed according to a specific conserved sequences screened from V. parahaemolyticus. Subsequently, the feasibility, specificity, and sensitivity of the method were evaluated after the optimization of reaction conditions. Furthermore, V. parahaemolyticus-contaminated aquatic products were used to validate the interference resistance of the method. Results The cleavage of CRISPR/Cas13a was activated upon binding to the target RNA (T-RNA), leading to the trans-cleavage of the RP/I cascade probe and the release of I strand. Then, the released I strand subsequently triggered HCR, generating a significant fluorescence signal for target detection. The established method successfully distinguished target sequences with single-base, double-base, and triple-base mismatches and enabled the specific identification of V. parahaemolyticus against other non-target bacteria, including V. alginolyticus, V. vulnificus, V. harveyi, V. cholerae, and Escherichia coli, demonstrating excellent specificity. The assay showed a good linear correlation over a T-RNA concentration range of 25 pmol/L to 10 nmol/L. The corresponding linear regression equation was y=7 236.75×lg C_T-RNA-8 590.11 (R²=0.99, C represents the T-RNA concentration and y represents the fluorescence intensity), with the LOD of 1.01 pmol/L. The proposed method enabled rapid detection of RNA extracted from V. parahaemolyticus in various aquatic products, yielding results consistent with those obtained by RT-qPCR. Conclusion The fluorescence method based on CRISPR/Cas13a-HCR established in this study realizes rapid detection of V. parahaemolyticus, demonstrating good sensitivity, specificity, and accuracy.