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 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.

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 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 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.

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.

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 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 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 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.