The dinitroaniline herbicide pendimethalin, as a pre-emergent herbicide, is widely employed for weed control in cotton fields across Xinjiang. Characterized by chemical stability, prolonged residual activity, bioaccumulative potential, and biomagnification, it is extensively applied in agricultural practice, leading to increased risks to soil ecosystems. Accordingly, the removal of pendimethalin residues has garnered increasing attention. [Objective] To enrich the microbial consortia with pendimethalin-degrading ability, study succession characteristics of microbial consortia during the enrichment culture process under pendimethalin stress, and identify the key microorganisms involved in pendimethalin degradation. [Methods] The cotton field soil under long-term pendimethalin stress was inoculated into MSM media with pendimethalin at 0, 1.2, and 12 mg/L, respectively. The succession of the microbial consortium structure under pendimethalin stress was investigated by high-throughput sequencing. [Results] Two microbial consortia capable of degrading pendimethalin were enriched. Among them, L4 (low-concentration group) achieved a degradation rate of 100% for 1.2 mg/L pendimethalin within 11 days, while H4 (high concentration group) showed a degradation rate of 37.2% for 12 mg/L pendimethalin over the same period. The alpha diversity of microbial consortia was considerably decreased by pendimethalin stress, and the bacteria responded to the stress more strongly than fungi. The microbial consortium structure varied with different concentrations of pendimethalin. The network stability, complexity, and modularity were diminished by pendimethalin stress. Linear discriminant analysis effect size (LEfSe) results showed that the specific bacterial taxa in the high concentration group were Achromobacter, Leifsonia, Candidatus_Nucleicultrix, Enterobacter, and Chryseobacterium. The specific bacterial taxa in the low concentration group were Methyloversatilis, Pseudoxanthomonas, Ancylobacter, Methylorubrum, Thermomonas, and Pseudoflavitalea. Talaromyces, Trichoderma, Paracremonium, Scedosporium, and Sarocladium were the specific fungal taxa. The PICRUSt2 analysis showed the pendimethalin stress significantly enriched the pathways related to degradation. The correlation analysis between microbial genera and pendimethalin degradation showed that Methylorubrum, Hyphomicrobium, Microbacterium, Rhodopseudomonas, and Fusarium had positive correlations with pendimethalin degradation in the low concentration group. Hyphomicrobium, Leifsonia, Rhodopseudomonas, Talaromyces, and Trichoderma were positively correlated with pendimethalin degradation in the high concentration group. [Conclusion] Two microbial consortia capable of degrading pendimethalin were successfully obtained through enrichment culture under varying concentrations of pendimethalin. Leveraging high-throughput sequencing, this study systematically explored the succession patterns of microbial consortia under pendimethalin stress. Key functional microorganisms associated with pendimethalin degradation were preliminarily identified. The findings provide a theoretical basis for the targeted screening of efficient microbial strains dedicated to pendimethalin degradation.

The fruiting bodies of fungi of genus Shiraia inhabiting bamboo have a medicinal use in traditional Chinese medicine. Hypocrellin A (HA), the main bioactive perylenequinone pigment from S. bambusicola fruiting bodies is a novel non-porphyrin photosensitizer with antitumor and antimicrobial properties. [Objective] To investigate the effects of Shiraia fruiting body-associated fungi on HA biosynthesis and develop a co-culture method for enhancing HA production. [Methods] Shiraia fruiting body-associated fungi were isolated and the strains influencing HA biosynthesis were screened by a plate confrontation assay. The effects of intracellular and extracellular metabolites of the strains on HA production were evaluated. A co-culture system for Shiraia sp. S9 and associated fungi was established and optimized for enhancing HA production. [Results] There were 34 fungal strains including 6 host Shiraia strains isolated from the fruiting bodies. Among them, Fusarium sp. SF12 and its extracellular polysaccharides significantly promoted HA biosynthesis. Fusarium sp. SF12 did not noticeably affect the growth of Shiraia sp. S9 but regulated HA synthesis by upregulating the transcription levels of key enzyme genes involved in HA biosynthesis. The total HA yield was enhanced to 209.46 mg/L on day 8 after adding spores (100 cell/mL) from Fusarium sp. SF12 to the Shiraia culture at the time point of 24 h, which was 1.93 times that of the control. [Conclusion] There are diverse fungi in Shiraia fruiting bodies. The co-culture of the associated fungus Fusarium sp. SF12 and the host Shiraia sp. S9 is a new technique to improve HA production.

Aureobasidium spp. are a group of fungi with remarkable ecological adaptability and stress tolerance. They are ubiquitous in natural environments such as plants and can survive under extreme conditions. The genomes of Aureobasidium spp. show specific differentiation characteristics, and the strains have obviously advantage characteristics in fermentation. Aureobasidium spp. can utilize a broad spectrum of carbon sources and produce a rich variety of metabolites. Aureobasidium spp. and their metabolites have significant application potential in fields such as biomedicine, biocontrol, and food processing. This article introduces the distribution, classification, main metabolites, and multidisciplinary applications of Aureobasidium spp. In the future, with the advancement in multidisciplinary fields such as genome editing and intelligent biomanufacturing, Aureobasidium spp. are expected to play an important role in biomanufacturing and sustainable development industries.

Plant endophytes are non-pathogenic microbial groups residing inside or in the interstices of plant tissue. They constitute a pivotal component of the plant microecological environment. These organisms are distinguished by their remarkable biodiversity and wide distribution across diverse regions of the host plant. Plant endophytes exhibit high species diversity, host plant diversity, habitat diversity, and functional diversity. They can secrete hormones that regulate plant growth and enhance the nutrient absorption capacity of their hosts to promote plant growth. Additionally, endophytes can promote plant growth indirectly by enhancing the host plant resistance to abiotic and biotic stresses. Notably, these endophytes are capable of producing substantial secondary metabolites, which exhibit antimicrobial, antiviral, antioxidant, and other biological activities. This capacity offers considerable potential for the development of novel pharmaceuticals, the extraction of natural products, and the creation of biopesticides. Endophytes have a wide range of applications in agriculture, industry, and medicine. They can be used as biocontrol agents to enhance crop yields or used for the production of natural pigments and perfumes and the development of novel pharmaceuticals. However, the research on plant endophytes still faces many challenges in species identification and function verification, molecular mechanism analysis of endophyte-host interactions, practical application technology, and safety evaluation.

Tomato bacterial wilt caused by Ralstonia solanacearum seriously affects the yield and quality of tomato and brings serious economic losses and challenges to the tomato planting industry. [Objective] To achieve efficient biocontrol of tomato bacterial wilt by Streptomyces, providing a solid theoretical foundation for the development of biocontrol agents. [Methods] Six biocontrol strains of actinomyces (AB_1 to AB_6) exhibiting potent inhibitory activities against R. solanacearum were isolated from soil samples. The morphological, physiological, biochemical, and taxonomical characteristics of these strains were determined. Additionally, the extracellular enzyme activities and rhizosphere colonization abilities of the strains were analyzed. Furthermore, a greenhouse pot experiment was conducted to evaluate the biocontrol efficacy of these strains against tomato bacterial wilt. [Results] The inhibitory zone diameters of the strains against R. solanacearum ranged from 1.76 cm to 6.76 cm. Comparative analysis of the 16S rRNA gene sequences revealed that all the six strains belonged to the Streptomyces. The sequence similarities between strain AB_1 and Streptomyces gardneri, AB_2 and S. pratensis, AB_3 and S. diastatochromogenes, AB_4 and S. canus, AB_5 and S. albiflavescens, and AB_6 and S. gramineus were 98.67%, 97.59%, 97.33%, 96.54%, 96.94%, and 97.34%, respectively. Pot experiments demonstrated that these six Streptomyces strains prevented tomato bacterial wilt with the efficacy ranging from 69.23% to 100.00%. All the six strains successfully colonized the tomato rhizosphere and exhibited activities of diverse extracellular enzymes including esterase, amylase, and urease. Additionally, they displayed extensive utilization of carbon and nitrogen sources along with robust tolerance towards variations in pH and salt concentrations. [Conclusion] The six strains of Streptomyces exhibited remarkable environmental adaptability and demonstrated efficient colonization in the tomato rhizosphere. Moreover, they displayed potent antagonistic activity against tomato bacterial wilt in pot experiments. These findings align with the principles of sustainable agriculture and provide both theoretical and experimental evidence for utilizing Streptomyces as a preventive and management strategy against tomato bacterial wilt.

[Objective] To mine the macrofungal strains capable of efficiently degrading straw at low temperatures, thereby improving the utilization efficiency of straw resources, we measured the lignocellulose degradation abilities of 955 macrofungal strains. [Methods] First, we employed the plate method to screen the strains with carboxymethyl cellulase, xylanase, and laccase activities. Then, we carried out a filter paper degradation test to screen the cellulose-degrading strains. Finally, we performed liquid fermentation with the selected strains and measured their enzyme activities on days three, six, nine, and 12 to identify the dominant strains with strong lignocellulose-degrading abilities. [Results] We identified 11 macrofungal strains exhibiting strong lignocellulose degradation capabilities at a low temperature (15 ℃). The 11 strains were Trametes suaveolens, Irpex lacteus, Crucibulum laeve, Stereum hirsutum, Pleurotus ostreatus, Phlebia acerina, Agaricus xanthodermus, Neofomitella fumosipora, Pholiota multicingulata, Abortiporus biennis, and Armillaria cepistipes. Notably, C. laeve, A. xanthodermus, and P. multicingulata were newly reported for their high lignocellulose-degrading abilities. The maximum activities of carboxymethyl cellulase, xylanase, and laccase in the 11 strains reached 262.31, 91.03, and 196.50 U/mL, respectively. T. suaveolens exhibited carboxymethyl cellulase activity of 168.17 U/mL at 15 ℃, which was significantly higher than that (67.88 U/mL) observed at room temperature. P. ostreatus showed the carboxymethyl cellulase activity of 150.78 U/mL and the laccase activity of 154.32 U/mL. S. hirsutum achieved the laccase activity of 63.27 U/mL at 15 ℃, which was twice the level measured at room temperature. [Conclusion] We successfully identified 11 macrofungal strains with strong lignocellulose-degrading abilities at 15 ℃. The findings provide valuable microbial resources for the degradation of lignocellulose in cold regions and lay a theoretical basis for application of these strains in low-temperature industries.

[Objective] To explore the diversity of culturable bacteria in the mudflat sediments of the Pearl River Estuary in Guangdong Province and to mine strain resources capable of degrading microplastics from these sediments. [Methods] Five media were used for microbial isolation, and phylogenetic analysis was performed by MEGA-X software. The polyethylene terephthalate (PET) medium was selected to screen PET microplastic-degrading strains, and then gene function annotation was performed. [Results] A total of 265 bacterial strains belonging to 71 genera, 32 families of 4 phyla were isolated, including 168 (63.40%) strains of Pseudomonadota, 38 (14.34%) strains of Actinomycetota, 31 (11.70%) strains of Bacillota, and 28 (10.56%) strains of Bacteroidota. Based on the homology of 16S ribosomal RNA (16S rRNA) gene sequences, it was hypothesized that 59 of these strains might be potential new species. From the isolated strains, one PET microplastic-degrading strain was screened. [Conclusion] This study successfully obtained unique microbial resources from the tidal flats of Xiangzhou District, Zhuhai City and one strain capable of degrading PET and using PET as the sole carbon source.

[Objective] To screen and identify the plant growth-promoting bacterial strain with saline-alkali tolerance and evaluate its functions. [Methods] The rhizosphere soil of wheat was collected from different saline-alkali regions, and the highly efficient saline-alkali-tolerant bacterial strain was isolated by enrichment under saline-alkali condition and dilution coating. The antifungal spectrum and plant growth-promoting effects of the isolate were evaluated in vitro, and the nitrogenase activity was measured by an ELISA kit. The strain was identified based on the morphological, physiological, biochemical characteristics and phylogenetic analysis. The effect of the strain on wheat growth under salt stress was investigated by a pot experiment. [Results] A highly abundant bacterium with saline-alkali tolerance was enriched from rhizosphere soil and designated as TaRb44, which could grow normally under 3% NaCl and pH 10.0. Strain TaRb44 showed strong antagonism against soil-borne pathogenic fungi such as Fusarium pseudograminearum causing wheat crown rot, Fusarium oxysporum f. sp. niveum causing watermelon Fusarium wilt, and Fusarium oxysporum f. sp. cubense causing banana wilt, as well as Botrytis cinerea causing gray mold of postharvest tomatoes. Further tests showed that strain TaRb44 produced a variety of plant growth-promoting substances such as siderophores, amylase, and cellulase, and it had nitrogen fixation activity with the nitrogenase level of 65.50 U/L. Finally, the strain TaRb44 was identified as Paenibacillus polymyxa, which significantly promoted the growth of wheat seedlings and increased the root biomass under both salt stress and non-salt stress conditions. [Conclusion] In this study, P. polymyxa TaRb44 was obtained with much excellent properties such as disease prevention, plant growth promotion, and saline-alkali tolerance. It serves as an elite strain for developing new microbial fertilizer and soil amendments in the future.

[Objective] Arbuscular mycorrhizal (AM) fungi are crucial components of the plant rhizosphere microbiota, capable of forming symbiotic relationships with 72% of terrestrial plants. However, AM fungi are plant-specific symbiotic fungi in soil, and they are difficult to be enriched for isolation and achieve artificial pure culture. This study aimed to develop a non-plant symbiotic culture system based on the addition of root exudates to solve the problem of difficult invitro culture of AM fungi. [Methods] The “multi-layer sandwich” culture system was used for the in vitro quasi-asymbiotic culture of AM fungal spores from soil. Molecular systematics methods were employed to identify the cultured AM fungi. [Results] A “multi-layer sandwich” culture system was used for the in vitro quasi-asymbiotic culture of AM fungi from soil. It was found that the root exudates of Astragalus sinicus effectively promoted the hyphal growth of AM fungi. A large number (951±45) of secondary spores were produced after 60 days of culture, exceeding those after 30 days and 45 days of culture. Further spore inoculation tests indicated that the secondary spores produced from this culture colonized the roots of A. sinicus seedlings. Two AM fungal species, Funneliformis mosseae and Paraglomus occultum, were identified by molecular characterization as suitable for the “multi-layer sandwich” culture system. Finally, a nutrient solution composed of simulated root exudate components from A. sinicus was used for the “multi-layer sandwich” culture of AM fungal spores. The results showed that the addition of root exudates significantly promoted the hyphal growth of AM fungi. [Conclusion] In the plant-assisted “multi-layer sandwich” culture system, the root exudates of A. sinicus can continually induce AM fungi to produce hyphae and secondary spores capable of colonizing host plants under non-symbiotic conditions. This study provides a new method for solving the problem related to the in vitro culture, isolation, and identification of AM fungi.

[Objective] To investigate the structural characteristics of microbial communities in the soil samples with varying salt types and their associations with salt ions, thus laying a theoretical foundation for the amelioration of saline-alkali soil. [Methods] Soil samples were collected from three regions: Shijiazhuang (LC), Hengshui (SZ), and Cangzhou (HX) at 38°N. The total soluble salt content (TSS), salt ions, enzyme activities, and microbial community structures were measured. Mantel analysis was performed to examine the correlations between soil salt characteristics and microbial community structures. [Results] In the LC, SZ, and HX regions, the levels of soil electric conductivity, TSS, Na⁺, Cl^-, SO₄^2-, and NO₃^- showed a significant increasing trend, while the activities of four soil enzymes (invertase, alkaline phosphate, urease, and catalase) exhibited significant decreases, indicating that nutrient cycling was inhibited in saline-alkali soil. The β diversity of bacteria and fungi exhibited significant differences among the soil samples of three salt types. The α diversity of both bacteria and fungi in SZ showed significant differences from that in LC. In HX, the abundance of halophilic phyla such as Gemmatimonadota and Myxococcota, as well as the taxa with the function of ureolysis, significantly increased, while that of nitrogen-fixing taxa decreased. Mantel analysis indicated that salt ions such as Na⁺ and Cl^- had significantly negative correlations with microbial community composition but positive correlations with halophilic bacteria, such as Gemmatimonadota. [Conclusion] Microbial communities in the soil samples with different salt types exhibited significant differences. Salt ions drove structural changes of microbial communities in soil by inhibiting non-halophilic microorganisms and selectively enriching halophilic species. The alterations in microbial communities and the reduction in soil enzyme activities are key factors contributing to the impairment of nutrient cycling and supply in saline-alkali soil. This study lays a theoretical foundation for the regulation of key microbial populations in the amelioration of saline-alkali soil.