Abstract:Halogenated organic pollutants, owing to their persistence, high toxicity, and bioaccumulation, have become a formidable challenge for global environmental governance. Dehalogenating microbial biotechnology is a key green technology addressing this challenge, focusing on microbially-mediated dehalogenation processes, which hold significant importance for contaminated site remediation, industrial production, and fundamental research. This special issue on “Dehalogenating Microbiology” presents the latest advancements in frontier research and application technology within this field. The collection covers four core themes: novel dehalogenating microbial resources and metabolic diversity, including the domestication and characterization of obligate organohalide-respiring bacteria (OHRB), as well as the excavation of strains from deep-sea cold vents and facultative dehalogenators; biotransformation of challenging and cross-boundary pollutants, specifically focusing on the discovery and mechanism of per- and polyfluoroalkyl substances (PFASs) defluorinating bacteria, and research on the degradation and transformation of chlorinated flame retardants; complex environmental control on dehalogenation processes, deeply exploring the influence of microplastics, co-existing pollutants (such as perfluorooctane sulfonic acid (PFOS)), and different carbon sources on the activity of dehalogenating microorganisms; and advanced analytical technologies and engineering strategies, including the application potential of compound-specific isotope analysis (CSIA) and microbial-non-biological coupling remediation strategies. The publication aims to promote progress and breakthroughs in the principles and mechanisms, microbial resources, and remediation applications of “Dehalogenating Microbiology”, accelerating its transition from an environmental “ecological participant” to the core of “green biomanufacturing”, thereby providing technical support for global environmental sustainable development.

Abstract:Organochlorine compounds are common persistent pollutants in groundwater and soil, posing a serious threat to the environment and human health due to their high toxicity and difficult degradability. Microbial remediation characterized by low costs, high efficiency, and environmental friendliness has become an important method for treating organochlorine pollution, with anaerobic reductive dechlorination as the core mechanism. Trichlorobacter, a genus of facultative organichalide-respiring bacteria, possesses diverse metabolic functions and shows great potential in environmental remediation. In this paper, we systematically reviewed the microbiological properties including the taxonomic changes of Trichlorobacter and elaborated on the discovery and isolation methods of the strains. Particularly, we analyzed the physiological and biochemical properties, including organohalogen respiration, iron reduction, nitrate reduction, and sodium fumarate reduction. The genomic studies reveal the phylogenetic relationships and functional gene characteristics of different strains, especially the key role of reductive dehalogenases (RDases) in the dechlorination process. In addition, this paper discusses the synergistic mechanism between Trichlorobacter and other microorganisms (such as Dehalococcoides), as well as the application cases of Trichlorobacter in the remediation of organochlorine-contaminated sites. Finally, in view of the current research deficiencies, future research directions are proposed, including optimizing the environmental adaptability of strains and developing multi-strain combined remediation technologies. This review aims to provide theoretical support and technical references for the efficient biological remediation of organochlorine pollution.

Abstract:Chlorinated hydrocarbons, with high toxicity and persistence, are major environmental pollutants posing challenges to soil and groundwater remediation. Currently, bioremediation strategies primarily rely on anaerobic reductive dechlorination, which is often hindered by the accumulation of toxic intermediates (such as vinyl chloride) and the stringent environmental requirements of obligate dechlorinating bacteria, thus demonstrating limited remediation efficiency. To overcome these limitations, microbial oxidative degradation of chlorinated hydrocarbons has gained increasing recognition as a promising alternative. Key advantages of this approach include the prevention of toxic intermediate accumulation, broad environmental tolerance of degrading microorganisms, and enhanced metabolic efficiency. This review evaluates the limitations of anaerobic reductive dechlorination, summarizes recent advances in microbial oxidative degradation, including functional strains, metabolic pathways, current challenges in bioremediation, and concludes with prospective strategies for advancing direct oxidative bioremediation.

Abstract:Chlorinated methanes including carbon tetrachloride, chloroform, dichloromethane, and chloromethane are widely present in the soil and underground water at contaminated sites. With high toxicity, high stability, strong volatility, and resistance to biodegradation, chlorinated methanes have aroused public concern about their threats to environmental, ecological, and human health. Microbial dechlorination has gained attention as an environmental-friendly and cost-effective remediation strategy. This review systematically summarizes the microbial dechlorination mechanisms of chlorinated methanes, with a focus on the dechlorination process catalyzed by reductive dehalogenases in typical organohalide-respiring bacteria such as Dehalobacter and Desulfitobacterium, as well as metabolic pathways (e.g., the Wood-Ljungdahl pathway) for dichloromethane mineralization. In addition, this review highlights key environmental factors influencing microbial dechlorination efficiency and explores the substrate inhibition effects caused by the coexistence of multiple pollutants. Furthermore, the potential of indirect dechlorination mediated by microbial generation of compounds such as iron sulfide (FeS) is explored. Finally, a microbe-mineral synergistic dechlorination strategy is proposed, which integrates the advantages of abiotic reductive materials and organohalide-respiring microorganisms to achieve efficient and complete degradation of chlorinated methanes. This review provides theoretical foundations and technical insights for the in-situ remediation of chlorinated methane-contaminated sites.

Abstract:Organohalide-respiring bacteria (OHRB) are anaerobic microorganisms that utilize organohalides as terminal electron acceptors and conserve energy through reductive dehalogenation. They play a pivotal role in the global carbon-halogen cycle and the natural attenuation of pollutants. This review systematically summarizes research advances in OHRB, covering their phylogenetic diversity, energy metabolism mechanisms, and ecological functions. The metabolic characteristics and ecological interactions of key genera, including Dehalococcoides, Dehalogenimonas, Dehalobacter, and Desulfitobacterium, are analyzed, and the structural and functional diversity of reductive dehalogenases (RDases) is summarized. Furthermore, this review explores the application potential of OHRB in the in situ bioremediation of contaminated sites. Strategies such as the construction of synthetic ecosystems, bioelectrochemical control, and AI-driven model optimization are proposed to facilitate the transition of OHRB research from laboratory settings to engineering and ecosystem-level applications.

Abstract:Perchlorates are a class of persistent inorganic pollutants characterized by high water solubility, strong mobility, and endocrine-disrupting effects, posing a serious threat to global drinking water safety and ecosystem health. Biological treatment of perchlorates has attracted increasing attention due to its advantages of low costs and absence of secondary pollution. However, comprehensive reviews focusing on the biological reduction mechanisms of perchlorates and their engineering applications remain limited and require further systematic analysis. This review first employs bibliometric methods to systematically examine the research trends and hotspots related to biological treatment of perchlorates, with a particular focus on the underlying mechanisms and application potential of biological reduction processes. It then summarizes the diversity of perchlorate-reducing bacteria and elucidates the functional mechanisms of their key metabolic enzymes. Furthermore, typical biological treatment technologies and integrated treatment processes are evaluated in terms of removal principles and performance. Finally, future research directions are proposed, including the discovery of novel perchlorate-reducing strains, exploration of reduction mechanisms, development of biomimetic catalytic materials, and innovation in multi-technology integrated treatment processes. This review aims to provide theoretical support and strategic guidance for the efficient remediation of perchlorate pollution.

Abstract:Halogenated organic compounds (HOCs) are widely distributed in anaerobic environments such as soils and groundwater. They typically exhibit high persistence, bioaccumulation and toxicity, posing severe threats to human health and ecological security. In anaerobic conditions, microbial degradation mediated by organohalide-respiring bacteria (OHRB) represents a green and sustainable remediation strategy for HOCs-contaminated sites, garnering significant attention in recent years. However, challenges persist in practical field application, including difficulties in tracing pollution source, complex degradation processes, and difficulties in accurately evaluating remediation efficiency. Against this backdrop, compound-specific stable isotope analysis (CSIA) offers a novel approach to address these issues by capturing the isotope fractionation effect during the degradation processes. This study systematically reviewed the application progress of CSIA in the research on reductive dehalogenation of HOCs, with a particular focus on specific cases in mechanism analysis and in situ process assessment. Furthermore, this review also explored the future prospects of this technology in the studies on reductive dehalogenation mechanisms of various types of HOCs, aiming to provide theoretical support and technical reference for research on anaerobic microbial degradation of HOCs.

Abstract:The marine environment has been exposed to excessive halogenated organic compounds (HOCs) derived from natural and anthropogenic activities. Reductive dehalogenases (RDases), which are key enzymes for catalyzing microbial reductive dehalogenation, play an important ecological role in marine ecosystems and show great potential in the transformation or degradation of HOCs. Meanwhile, the marine environment serves as a key repository of RDases, especially for novel ones. This review summarizes the enzymatic characteristics of different categories of RDase and their identification and quantification methods, including a set of bioinformatic analysis workflow. Subsequently, this review discusses the environmental factors influencing the distribution of RDases in marine environments and summarizes the reports about geographic distribution characteristics of RDases in marine environments to suggest hotspots of microbial reductive dehalogenation. Furthermore, this review explores the weak correlations among RDase categories, their terrestrial and marine origins, and dehalogenation substrates. It discusses the application prospects of marine RDases and outlines their future research directions. This review aims to provide theoretical reference and support for the development of RDases and bioremediation technology for HOCs in marine environments.

Abstract:Per- and polyfluoroalkyl substances (PFASs) are recognized as major environmental contaminants due to their chemical stability, long-range transport potential, bioaccumulation properties, and ecotoxicity. These compounds, characterized by high dissociation energy of C−F bonds and stable helical molecular structures, demonstrate exceptional persistence in the environment, earning the designation of “forever chemicals”. Conventional physical and chemical treatment methods, including adsorption, membrane separation, and chemical reduction based on reactive species, are capable of partially removing PFASs. However, these methods face limitations related to high operational costs and complex processing requirements. Microbial defluorination has gained attention as a promising approach for PFAS remediation due to its environmental compatibility and sustainability. This paper provides a systematic overview of the biodegradation mechanisms of PFASs and other fluorinated organic compounds under both aerobic and anaerobic conditions. It details the roles of key enzyme systems, including hydrolytic dehalogenases, reductive dehalogenases, and cytochrome P450, in facilitating microbial defluorination. Additionally, the review highlights recent advancements in enhanced bioremediation strategies, such as bio-electrochemical systems, electron shuttle mediators, and the application of specialized microbial consortia. Finally, current challenges and potential future research directions in the biodegradation of PFASs are discussed.

Abstract:[Background] Desulfitobacterium, in conjunction with Dehalococcoides, plays a crucial role in the reductive dechlorination process of trichloroethylene (TCE) to ethylene. Per- and polyfluoroalkyl substances (PFAS) have been confirmed to severely inhibit the Dehalococcoides-catalyzed conversion of vinyl chloride (VC) to ethylene. However, the effect of PFAS on the Desulfitobacterium-catalyzed reduction of TCE to dichloroethylene (DCE) has not been systematically evaluated. [Objective] Given the widespread co-occurrence of PFAS and chlorinated hydrocarbons in the soil at firefighting training sites, investigating the effects of PFAS on Desulfitobacterium-mediated reductive dechlorination of TCE can clarify the risks associated with the failure of microbial remediation for TCE removal at such sites. [Methods] Microcosm experiments, real time fluorescence quantitative PCR, and high-throughput sequencing were employed to analyze the relationships of PFAS types/concentrations with the TCE transformation rate and the community structure and diversity of Desulfitobacterium. [Results] Microcosm experiments demonstrated that 50 mg/L perfluorooctane sulfonate (PFOS) significantly reduced the reductive dechlorination rate of Desulfitobacterium, whereas the same concentration of perfluorooctanoic acid (PFOA) showed no significant inhibitory effect. Within the range of 20–100 mg/L, the concentration of PFOS showed a negative correlation with the reductive dechlorination rate of TCE by Desulfitobacterium. PFOS with the concentration exceeding 20 mg/L significantly inhibited the reductive dechlorination rate of TCE. In the presence of PFOS≥80 mg/L, Desulfitobacterium completely lost its reductive dechlorination activity, and the fermentative bacterium Clostridium_sensu_stricto_7 lost its ability to metabolize lactate. PFOS significantly altered the compositional characteristics and genetic diversity of the Desulfitobacterium community, leading to changes in OTU abundance distribution and a notable reduction in the Shannon diversity index. [Conclusion] As an inhibitor of reductive dechlorination by Desulfitobacterium, PFOS at high concentrations in soil environments will increase the risk of microbial remediation failure for TCE.

Abstract:[Background] As emerging contaminants in aquatic environments, microplastics not only exhibit substantial sorption capacity for organic pollutants but may also reshape microbially mediated contaminant transformation through their unique bio-interface effects. [Objective] To elucidate how different types of microplastics influence the microbial reductive dehalogenation of organohalides. [Methods] Five representative microplastics, polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), and polyethylene terephthalate (PET), were examined for their sorption characteristics toward triclosan (TCS), tetrabromobisphenol A (TBBPA), and polychlorinated biphenyl 180 (PCB180), as well as their impacts on the microbial reductive dehalogenation of these compounds. [Results] The results showed that the adsorption capacities of the microplastics for TCS, TBBPA, and PCB180 ranged from 212.41 mg/kg to 585.32 mg/kg, varying due to the polar and structural differences of polymers. PVC and PET showed higher affinities and aging enhanced the adsorption. In sediment-water systems, microplastics accounted for 6.05%−22.68% of contaminant partitioning, which was substantially lower than that of sediments (42.98%−76.50%), indicating their role as “secondary distribution carriers”. PVC promoted the dehalogenation activity of Dehalococcoides mccartyi CG1, whereas PP exhibited a slight inhibitory effect. Organohalide-respiring bacteria showed higher abundance in the liquid phase (10⁷ copies/mL) than on microplastic surface (10⁵−10⁶ copies/mL). Community analysis revealed that the dominant dehalogenating taxa included Dehalococcoides, Dehalogenimonas, Clostridium, and Petrimonas, with fermentative bacteria forming mutually beneficial interactions with dehalogenators by supplying electron donors and carbon sources. Co-occurrence network analysis further demonstrated stronger microbial associations on microplastic surfaces, with PVC in particular forming a more compact network structure, suggesting enhanced metabolic cooperation. [Conclusion] This study demonstrates that microplastics modulate the transformation of halogenated organic compounds through combined sorption and biointerface effects. Their physicochemical properties and microbial interactions jointly determine their environmental behavior and ecological impacts.

Abstract:[Background] Trichloroethylene (TCE) is a prevalent chlorinated organic pollutant. Microbial remediation serves as a cost-effective, environmentally friendly alternative to conventional physical and chemical methods, without secondary pollution. However, the scarcity of efficient anaerobic dehalogenating strains remains a key bottleneck. [Objective] This study isolated and identified organohalide-respiring bacterium, aiming to expand the bacterial resources available for the dehalogenation of pollutants such as TCE. [Methods] The dilution-to-extinction method was used to isolate a strain for anaerobic reductive dehalogenation from TCE-dechlotinating enrichment cultures. Strain purity was verified through eutrophic culture, polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), and Sanger sequencing. Phylogenetic analysis of the 16S rRNA gene and comparative genomic analysis were performed to determine the taxonomic affiliation of the strain. Fundamental characteristics of the strain, including its substrate spectrum, growth kinetics, antibiotic resistance profile, and dechlorination ability of contaminated groundwater environment, were determined. [Results] The isolated strain, designated GPTCE1 and phylogenetically assigned to Dehalococcoides mccartyi, efficiently dechlorinated five chlorinated hydrocarbons, including 1,1,2-trichloroethane, 1,2-dichloroethane, and TCE derivatives. When the inoculation amount was (1.5±0.4)×10⁸, the strain showed a TCE dehalorination rate reaching (2.3±0.3) μmol/d and a growth yield of (2.1±1.2)×10⁸ gene copies/μmol Cl⁻, being capable of completely transforming TCE into ethylene. In a contaminated groundwater environment, inoculation of the strain at (3.7±0.3)×10⁸ cells achieved a TCE dechlorination rate of (4.3±0.2) μmol/d. Furthermore, strain GPTCE1 exhibited resistance to vancomycin, ampicillin, and streptomycin. [Conclusion] A D. mccartyi strain, GPTCE1, was successfully isolated from TCE-dechlotinating enrichment cultures. Systematic characterization revealed its efficient dechlorination capability, establishing it as a valuable microbial resource for advancing in situ bioremediation technologies.

Abstract:[Background] Tris(1-chloro-2-propyl) phosphate (TCPP), a widely used additive organophosphate flame retardant, is extensively applied in vehicle interiors, electronic appliances, and household furniture. With the rapid increase in global end-of-life vehicles, vehicle dismantling sites have become significant hotspots of TCPP contamination. However, the microbial transformation processes and mechanisms of TCPP in such complex environments remain unclear. Previous studies suggested that organohalide-respiring bacteria (OHRB) may participate in the anaerobic biotransformation of TCPP via reductive dehalogenation, while the catalytic mechanism of reductive dehalogenase and its coding gene have not been identified. [Objective] To reveal the pathways and molecular mechanisms underpinning the anaerobic transformation of TCPP by a microbial culture enriched from a vehicle dismantling site, identify the key functional microorganisms, and characterize the reductive dehalogenase (rdhA) genes involved in TCPP transformation. [Methods] An anaerobic microbial culture capable of efficiently transforming TCPP was enriched from sludge of a vehicle dismantling site. Transformation products were identified by high-resolution LC-MS. Key functional microorganisms and genes involved in TCPP transformation were identified by high-throughput sequencing, metagenomic binning and RT-qPCR. [Results] Five TCPP transformation products were identified, with propene and bis(1-chloro-2-propyl) phosphate (BCPP) being the primary transformation products. The genome of Dehalococcoides contained eight rdhA genes, among which one rdhA gene, designated perA, showed significantly upregulated transcription with TCPP amendment. [Conclusion] This study confirmed the anaerobic transformation potential of sludge microorganisms from a vehicle dismantling site toward TCPP, identified five transformation products, and proposed that TCPP was mainly transformed into propene and BCPP via a dechlorination pathway involving the cleavage of C−Cl and C−O bonds. The perA gene in Dehalococcoides might play a critical role in the dechlorination of TCPP. The findings enhance the understanding of the environmental behavior mechanisms of chlorinated organophosphate esters and provide a theoretical basis for the bioremediation of TCPP-contaminated sites.

Abstract:[Background] Per- and polyfluoroalkyl substances (PFAS) are emerging persistent pollutants recalcitrant to biodegradation due to the strong C−F bonds. While biodefluorination of mono-fluorinated compounds has been reported, studies on the biodefluorination of polyfluoroalkyl substances, specifically by pure cultures, remain limited. [Objective] To isolate bacteria that can defluorinate mono-fluorinated substances and assess their capability of defluorinating PFAS. [Methods] A defluorinating strain, Nocardioides sp. NJF-4, was isolated with 1-fluorodecane (FD) as the sole carbon source. Colorimetric detection of fluoride was employed to evaluate the defluorinating effects of NJF-4 on the tri-fluorinated compound 4,5,5-trifluoropent-4-enoic acid (TFE) and the hexa-fluorinated compound 4,4,4-trifluoro- 3-(trifluoromethyl)crotonic acid (SFC). [Results] NJF-4 effectively utilized FD as the sole carbon source, with a defluorination rate of (70.5±5.4)% after 7 days of incubation in the minimal medium (MM) with FD. With TFE as the carbon source in the MM-G medium, NJF-4 exhibited a degradation rate of (42.0±2.6)% and a defluorination rate of (11.70±0.66)% on day 28. With SFC as the carbon source in the MM-G medium, NJF-4 exhibited a degradation rate of (36.70±0.87)% and a defluorination rate of (2.57±0.15)% on day 49. The addition of ammonium acetate significantly improved the biodefluorination of poly-fluorinated compounds. Under cometabolic conditions, the defluorination efficiency on TFE reached (21.2±1.9)%, a 1.8-fold increase compared with that in the absence of ammonium acetate, while the defluorination efficiency on SFC was (9.61±0.72)%, representing a 3.7-fold increase. Under cometabolic conditions, the degradation of TFE showed no significant increase, whereas that of SFC was significantly enhanced. The relative defluorination efficiency was significantly improved following the addition of ammonium acetate. [Conclusion] NJF-4 capable of defluorinating mono-fluorinated compounds can also defluorinate poly-fluorinated compounds. The biodefluorination of PFAS was significantly stimulated under cometabolic conditions. The isolation of defluorinating bacteria provides a foundation for exploring the mechanisms underlying biodefluorination.

Abstract:[Background] 2,4,6-tribromophenol (TBP) is a typical halogenated organic contaminant with high environmental persistence, bioaccumulation potential, and biological toxicity, posing serious threats to marine ecosystems. Cold seep sediments harbor diverse anaerobic microbial communities, which may contain functional microorganisms with the function of reductive dehalogenation of organohalides. [Objective] We investigated the microbial communities with the function of TBP degradation from cold seep sediments and characterized their taxonomic composition and metabolic potential, aiming to lay a research foundation for isolating anaerobic reductive dehalogenating microorganisms from cold seep sediments and provide microbial evidence supporting the bioremediation of halogenated pollutants. [Methods] With TBP as the sole electron acceptor, anaerobic reductive dehalogenating microorganisms were isolated from the sediment samples collected at four depths of a marine cold seep. Metagenomic sequencing was performed to analyze the microbial community composition, rdhA distribution, and metabolic characteristics. [Results] All enrichment cultures exhibited TBP debromination activity, with Pseudomonadota and Bacillota identified as the dominant bacterial phyla. Notably, the enrichment culture derived from the 150 cm sediment layer below the seafloor showed the highest TBP degradation efficiency. Moreover, this culture contained the greatest number and highest abundance of rdhA, which were eight to 12 times higher than those in the other three enrichment cultures. A total of 23 high-quality metagenome-assembled genomes (MAGs) carrying rdhA were recovered, all of which belonged to Bacillota. On the basis of GTDB taxonomy and average nucleotide identity analysis, several putative reductive dehalogenating microorganisms were identified, most of which have not yet been isolated or cultivated. In addition, metabolic pathway analysis based on ten high-quality non-redundant MAGs (completeness>90%) indicated that these organohalide-respiring bacteria generally lacked a complete de novo cobalamin biosynthesis pathway, but all were capable of synthesizing functional cobalamin via the salvage pathway. [Conclusion] These findings expand our understanding of the taxonomy and functional diversity of reductive dehalogenating microorganisms in cold seep environments and contribute to the exploration and utilization of deep-sea microbial resources.

Abstract:[Background] Halogenated organic pollutants have drawn extensive attention due to their mutagenesis, carcinogenesis, and teratogenesis. And the emerging of pollutants has further increased the difficulty of pollution control. Microbial reductive dehalogenation has been widely applied for its environmental friendliness. Gradient acclimation is often used to enrich functional microorganisms and enhance the efficiency of pollution remediation. [Objective] To assist in resolving the problem of acclimating organohalide-respring bacteria, this study focuses on clarifying the feasibility and specific mechanisms of gradient acclimation to enrich the bacterial consortium. [Methods] The typical emerging brominated flame retardant, tetrabromobisphenol A (TBBPA), was selected as the model pollutant. The original consortium was obtained from the soil contaminated by halogenated organic pollutants. Then, it was enriched by gradient acclimation with 1, 2, 5, and 10 mg/L TBBPA in sequence. The community succession mechanism was analyzed through high-throughput sequencing. [Results] The removal of TBBPA was greatly improved after gradient acclimation. The degradation products were dominated by bisphenol A. The consortium mainly consisted of Firmicutes (74.6%) and Bacteroidota (15.9%). And Acinetobacter and Pseudomonas were potential functional genera for dehalogenation. During the acclimation, the α-diversity of the consortium decreased and the contribution of the deterministic process to the community assembly increased gradually. Microbial co-occurrence network analysis showed that the acclimation enhanced the interspecies interactions and improved the metabolic stability of microorganisms. The fermentative genera were continuously enriched, and played an important role in the degradation. [Conclusion] Gradient acclimation can enrich dehalogenating microorganisms, optimize microbial interaction networks, and be used to construct efficient microbial communities for dehalogenation. This study provides a reference for the control of emerging halogenated organic pollutants based on microorganisms.

Abstract:[Background] Sulfidated nano-scale zero valent iron (S-nZVI) has been extensively investigated for the remediation of chlorinated hydrocarbon (CAH)-contaminated groundwater due to its high reductive dechlorination activity and enhanced electron utilization efficiency. Sulfidation modification can improve the reactivity of nZVI toward CAHs and suppress parasitic reactions with water. However, conventional chemical sulfidation methods are often costly and complex, which limit their large-scale application. Recently, a biologically mediated sulfidation approach using sulfate-reducing bacteria (SRB) has attracted increasing attention. This strategy employs sulfide metabolites from SRB to achieve in situ sulfidation of nZVI, offering a greener and more sustainable alternative. Nevertheless, the role of nZVI dosage in shaping the interfacial structure and dechlorination performance of the resulting biogenic sulfidated nZVI (S-nZVI^bio) remains unclear. [Objective] To elucidate how different nZVI dosages in SRB systems affect the interfacial structure of S-nZVI^bio and its reductive dechlorination performance toward trichloroethene (TCE). [Methods] SRB-nZVI coculture systems were established with three nZVI dosages (0.1, 1.0, and 5.0 g/L) to obtain distinct S-nZVI^bio particles. Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) were employed to characterize particle morphology and surface chemistry, while batch experiments were conducted to evaluate TCE degradation kinetics, product distribution, and electron efficiency. [Results] At the low dosage (0.1 g/L), insufficient Fe²⁺ release resulted in incomplete FeS_x shell formation, and more microbial products were attached, leading to slow TCE degradation and low electron efficiency. At the high dosage (5 g/L), the relative scarcity of S²⁻ caused incomplete sulfidation. Although the highest TCE degradation rate was observed, the electron efficiency declined. At the medium dosage (1 g/L), Fe²⁺ and S²⁻ supply was well balanced, enabling the formation of a uniform and dense FeS_x layer, thereby achieving both rapid TCE degradation and high electron efficiency. [Conclusion] SRB-mediated sulfidation significantly enhanced the dechlorination performance of nZVI, while its effectiveness was governed by the Fe²⁺ and S²⁻ supply balance regulated by nZVI dosage. An appropriate nZVI dosage facilitated the formation of well-structured S-nZVI^bio with high dechlorination activity and electron efficiency. These findings provide theoretical support for designing efficient and sustainable biogenic sulfidation strategies of nZVI for groundwater remediation.

Abstract:[Background] Chlorinated aliphatic hydrocarbons have become persistent organic pollutants in soil and groundwater due to their extensive use in industrial and agricultural production and improper discharge, posing serious threats to the environment and human health. [Objective] To screen microbial consortia from a chemical production site that are capable of reductively dechlorinating perchloroethylene (PCE). [Methods] Enrichment culture techniques were employed to isolate PCE-degrading consortia from soil samples. The consortium composition and key strains were characterized via amplicon sequencing, 16S rRNA gene sequencing, and Sanger sequencing. GC-MS was used to monitor PCE and its dechlorination products. [Results] The enrichment culture from sample t1 successfully achieved the dechlorination of PCE. Microbial diversity analysis revealed that organohalide-respiring bacteria were dominated by Shewanella, and a strain preliminarily identified as Shewanella sp. BS1 was found within this enrichment culture. [Conclusion] This study demonstrates that the obtained enrichment culture mediates the reductive dechlorination of PCE. Although preliminary results suggest that Shewanella spp. may play a potential role in this process, further pure culture isolation and in-depth studies are still needed to definitively elucidate the specific dechlorination function and exact contribution of Shewanella sp. BS1 to the PCE transformation pathway. These findings provide a scientific basis for elucidating bioremediation mechanisms at chlorinated hydrocarbon-contaminated sites and informing subsequent engineering applications.

Abstract:[Background] perchloroethylene (PCE), a widely used chlorinated solvent, is a common pollutant in groundwater and soil due to its chemical stability and slow degradation. It poses serious threats to both the environment and human health. Bioremediation is one of the important means to deal with PCE pollution. [Objective] This study investigates the impacts of different carbon sources on the anaerobic degradation of PCE by dechlorinating bacterial strains or microbiotas, with the aim of optimizing conditions for the bioremediation of chlorinated pollutants. [Methods] Sodium acetate, sodium lactate, and methanol were selected as carbon sources. Four microbial systems (YANG microbiota, RICE microbiota, Dhc195, and CB1190) were evaluated for their PCE degradation efficiency. [Results] Sodium lactate was the most effective carbon source for PCE degradation, with all bacterial strains and microbiotas exhibiting degradation capability. The YANG microbiota exhibited the highest PCE degradation rate at 0.149 mmol/(L·d), achieving complete dechlorination of PCE within 14 days and producing ethylene (Eth) as the end product. The RICE microbiota reached a maximum degradation rate of 0.134 mmol/(L·d), completing PCE removal in 32 days and yielding cis-1,2-dichloroethylene (cis-DCE) and a trace amount of Eth. Strain CB1190 demonstrated a PCE degradation rate of 0.040 mmol/(L·d), generating cis-DCE and a minor amount of Eth after 38 days. In contrast, methanol proved the least effective carbon source, with only the YANG microbiota showing degradation capability at a rate of 0.045 mmol/(L·d) and a dechlorination period extended to 90 days. Moreover, no significant Eth production was observed. The RICE microbiota and strain Dhc195 showed no detectable PCE degradation activity in the methanol system. Sodium acetate was an intermediate carbon source between sodium lactate and methanol in terms of the degradation efficiency, and the end products contained rich Eth. With sodium acetate as the carbon source, the RICE microbiota had a degradation rate of 0.065 5 mmol/(L·d), completing PCE degradation within 8 days and yielding TCE, cis-DCE, and a trace amount of Eth. Strain Dhc195 did not show any degradation capability of PCE in the sodium acetate system, While its dechlorination activity could be activated by the addition of TCE, with a degradation rate of 0.037 8 mmol/(L·d) for TCE. Microbial community analysis of the YANG microbiota revealed significant differences under different carbon sources, with the relative abundance of Firmicutes, Bacteroidota, and Spirochaetota being 57%, 25%, and 12%, respectively, in the sodium lactate system. [Conclusion] In summary, sodium lactate is the most effective carbon source for enhancing PCE degradation, with the YANG microbiota showing the highest degradation rate and dechlorination efficiency. In contrast, methanol is not a suitable carbon source, as most microbial systems exhibit low or no degradation activity. Selecting an appropriate carbon source is crucial for enhancing PCE degradation efficiency, and the findings provide a theoretical basis for the remediation of actual contaminated sites.

Abstract:As an important industrial microorganism adhering to the criteria for food safety-applicable category, Bacillus subtilis is characterized by a clear genetic background, easy culture and genetic manipulation, non-pathogenicity and no endotoxin, and strong protein secretion, which make it an ideal host for the biosynthesis of heterologous proteins. With the development of synthetic biology, an increasing number of studies have focused on the screening and modification of protein expression components, including expression vectors, promoters, ribosome-binding sites, signal peptides, protein tags, and even chassis cell modification, for the expression of value-added functional proteins. However, the expression of heterologous proteins by B. subtilis still confronts issues such as incorrect folding and unclear mechanism of element-protein fitness. This review systematically summarizes the research progress and applications of protein expression elements in B. subtilis, integrating the latest element screening technologies and chassis cell engineering strategies. Finally, prospects are provided for improving the performance of existing systems and developing novel expression elements, aiming to promote the further application of B. subtilis in industrial biotechnology and synthetic biology.

Abstract:1,2,4-butantriol (BT), as an important fine chemical, is widely used in many fields. Chemical synthesis has many drawbacks, while biosynthesis has become a research hotspot due to its advantages of being mild, eco-friendly, and sustainable. This article provides a detailed review of the research progress in the biosynthesis of BT. In terms of the construction of synthetic pathways, this article introduces the synthetic pathways and key enzymes with xylose, glucose, arabinose, etc. as substrates. Metabolic engineering strategies cover blocking branch metabolic pathways, optimizing gene expression, modifying synthetic pathways, and balancing the supply of cofactors. Regarding the synthesis of BT by fermentation and whole-cell catalysis, this article discusses the effects of microbial culture conditions on yields and the characteristics of the two methods. In terms of the separation process of BT, this article compares the separation technologies and costs of the biological method and the chemical method. At present, the biosynthesis of BT is confronted with challenges such as limited activities of key enzymes, high costs of xylose, and technical bottlenecks in separation. In the future, the industrial production of BT can be promoted through screening and modification of key enzymes, exploration of new carbon sources, and artificial intelligence-assisted optimization of synthetic pathways.

Abstract:Zearalenone (ZEN), a mycotoxin produced by Fusarium, poses a persistent threat to global food security and animal husbandry, with estrogenic toxins presenting serious reproductive health risks. Current detoxification strategies for ZEN primarily include physical adsorption, chemical degradation, and biological detoxification. While physical adsorption is simple to operate, it may adversely affect feed quality. Chemical degradation is efficient but can generate secondary pollution. Biological detoxification, characterized by high efficiency, specificity, and environmental friendliness, has emerged as the most promising approach. This review systematically summarizes the toxicity mechanisms and health hazards of ZEN and compares the principles, applications, and limitations of the three detoxification approaches. Special emphasis is placed on biodegradation pathways and integrating protein structure prediction and molecular simulation techniques to elucidate the catalytic mechanisms and structure-function relationships of ZEN-degrading enzymes, providing new insights for rational enzyme design and performance optimization. In addition, we comprehensively discuss the molecular mechanisms, enzymatic characteristics, and industrial application challenges of ZEN-degrading enzymes, aiming to support the optimization and integration of multiple detoxification approaches. Despite numerous recent reviews on detoxification for ZEN, comprehensive studies comparing multiple detoxification strategies and delving into enzymatic degradation mechanisms remain limited. This review addresses these gaps and offers an outlook for future research.

Abstract:[Background] The invasive plant Wedelia trilobata presents wide distribution in southern China and a trend of expanding towards the north. Arbuscular mycorrhizal fungi (AMF) play a significant role in plant growth and responses to environmental stress. However, the role of AMF in the population expansion of W. trilobata and the adaptation of this plant to low-temperature stress remains unclear. [Objective] To investigate the role of AMF in the low-temperature stress responses of the Wenzhou and Sanya populations of W. trilobata, explaining the northward expansion of W. trilobata populations from the perspective of symbiotic microorganisms. [Methods] We selected stem segments of the Sanya and Wenzhou populations of W. trilobata from the southernmost and northernmost regions, respectively, of its current distribution in China, and used the stem segments of the native species W. chinensis as the control. We conducted a controlled pot experiment. The experiment was designed with inoculation of the AMF strain Rhizophagus intraradices and simulated low-temperature treatment. By analyzing the AMF colonization indices and the growth and physiological indices of plants from different populations, we explored the role of AMF in the adaptation of different populations of W. trilobata to low temperatures. [Results] AMF significantly enhanced the aboveground and belowground biomass of the Wenzhou and Sanya populations of W. trilobata at normal temperatures. Furthermore, AMF significantly increased the belowground biomass of the Wenzhou population at low temperatures. Meanwhile, the inoculation of AMF significantly improved the maximal photochemistry efficiency while significantly reducing the content of flavonols in the Wenzhou population at low temperatures. [Conclusion] AMF significantly promoted the growth of W. trilobata and significantly enhanced the tolerance of the high-latitude population to low temperatures. Therefore, we found that symbiosis with AMF may be one of the important microbial factors for the norward expansion of W. trilobata populations.

Abstract:[Background] The deterioration of the global eco-environment and the shortage of water resources have severely restricted agricultural and economic development and threatened people’s lives. China has defined the indicator (salinity of 5.0–10.0 g/L) of brackish water, which is mainly distributed in the northwest region and the eastern coastal areas. In some arid areas of the northwest, brackish water is even the only available water resource. Long-term consumption of brackish water is harmful to human health and can cause many problems in the agricultural and industrial sectors. Existing desalination methods have high investment and operation costs. [Objective] To achieve desalination of brackish water for alleviating the shortage of freshwater resources in China and explore eco-friendly, economical, and efficient technologies for brackish water desalination, so as to promote the development of China’s national economy and improve the living standards of the people. [Methods] We selected algal strains from the germplasm bank of terrestrial algal strains of Xinjiang Jinzheng Biotechnology Co., Ltd. The strains with salt tolerance were screened and their desalination effects on brackish water were investigated. The four algal strains (A-12, X-6, X-2, and Y-5) with salt tolerance were inoculated into 10 g/L brackish water at inoculation amounts of 10%, 30%, and 50% and aerobically cultured at room temperature (28±2) ℃, a light-dark ratio of 16 h:8 h, a light intensity of 5 000 lx for 10 days. During this period, the absorbance values, total salt content, and electrical conductivity of the water samples were measured. On the day when the experiment ended, the peroxidase activity was measured, and microscopic structures of the algal cells were photographed. [Results] The salt-tolerant microalgal strains screened out had desalination effects on brackish water. They reduced the salt content of brackish water from 10 g/L to 5.60 g/L and the electrical conductivity from 9.29 ms/cm to 5.27 ms/cm. The algal cells can grow and reproduce normally under the stress of high-concentration salt and showed no obvious difference in the cell morphology from the cells growing in the culture medium. With the increase in the inoculation amount of algal strains, the activities of superoxide dismutase and catalase increased accordingly. [Conclusion] When different amounts of algal liquids are inoculated into brackish water, the algal cells can grow and reproduce normally and reduce the salt content through the adsorption effect, thus desalinating brackish water.

Abstract:[Background] Ginseng Alternaria leaf and stem blight caused by Alternaria panax is one of the major diseases in ginseng production. It mainly occurs in Changbai Mountain and other ginseng-growing areas in China, causing severe losses to ginseng production. [Objective] To clarify the biological functions of the catalase-peroxidase gene ApKatG1 in A. panax. [Methods] The ApKatG1 knockout mutant and complemented mutant were obtained by homologous recombination. The effects of ApKatG1 on the growth rate, sporulation, responses to different stress factors, and pathogenicity were analyzed to elucidate the roles of ApKatG1 in A. panax. [Results] ApKatG1 encoded a catalase-peroxidase containing two typical peroxidase domains. The knockout mutant ΔApkatG1 exhibited the mycelial growth rate, conidiation level, and carbon utilization efficiency comparable to the wild type. However, ΔApkatG1 demonstrated enhanced sensitivity to environmental stress factors such as sorbitol and the cell wall stress factor Congo red, accelerated protoplast release, and significantly increased sensitivity to high concentrations of H₂O₂. The expression level of ApKatG1 significantly increased after H₂O₂ treatment. The knockout of ApKatG1 affected the expression of other catalase genes in A. panax. ApKatG1 did not participate in regulating the pathogenicity of A. panax in ginseng.[Conclusion] ApKatG1 plays a vital role in maintaining cell wall integrity and responding to H₂O₂ stress in A. panax.

Abstract:[Background] The extreme environments of Qinghai-Xizang Plateau harbor unique microbial resources with special biological activities. [Objective] To investigate the maize (Zea mays) growth-promoting effect of Bacillus atrophaeus NLHLT2 isolated from Qinghai-Xizang Plateau. [Methods] We employed bioactivity assays, whole-genome sequencing, and gene function analysis to characterize the bioactivity and related functional genes of the strain. The bacterial suspension with a concentration of 2×10⁸ CFU/mL was prepared and diluted in gradients of 100, 150, 200, 250, and 300 folds, and the optimal concentration for promoting plant growth was determined. Under low-temperature conditions, maize seedlings were treated with the strain suspension at the optimal concentration via root irrigation, and the effect of the suspension on maize growth was evaluated. [Results] Strain NLHLT2 exhibited significant antagonistic activities against plant pathogenic fungi Fusarium graminearum and Nigrospora oryzae. Meanwhile, the strain possessed the abilities to produce siderophores, gibberellins, and cytokinins and both salt and low-temperature tolerance. Under low-temperature conditions, root irrigation with the strain suspension (1×10⁶ CFU/mL) significantly enhanced the plant height, root length, leaf area, biomass, superoxide dismutase activity, peroxidase activity, and proline content, while markedly reducing the malondialdehyde content in maize seedlings. These effects collectively improved the physiological adaptability of maize seedlings to low-temperature stress. The complete genome sequence of strain NLHLT2 was 4 212 529 bp, with the G+C content of 43.29%. The genome contained functional genes associated with plant growth promotion and stress responses. [Conclusion] By studying the biological activity and genomic characteristics of strain NLHLT2, we analyze the genes related to growth promotion and stress tolerance, aiming to reveal the interaction mechanism between the strain and maize under low-temperature conditions. This study provides an elite strain and a theoretical basis for maize growth in high-altitude regions.

Abstract:[Background] Bacillus subtilis Bs-Z15 screened in the previous study was highly effective in controlling cotton Verticillium wilt, while high concentrations of this strain had a certain inhibitory effect on cotton growth. [Objective] To screen plant growth-promoting strains of Bacillus spp. for compounding with Bs-Z15 to construct a composite microbial agent to control cotton Verticillium wilt without inhibiting cotton growth. [Methods] Taking indole-3-acetic acid (IAA) production, phosphorus solubilization, nitrogen fixation, and siderophore secretion as the indicators for evaluating plant growth-promoting effects, we isolated Bacillus strains with high plant growth-promoting potential from the cotton field soil. The strains were identified through morphological observation, physiological profiling, biochemical assays, and 16S rRNA gene sequencing. Subsequently, pot experiments were conducted to evaluate the effects of the composite agent composed of the selected biocontrol strains and Bs-Z15 on both Verticillium wilt and cotton growth. The findings were further validated by field trials. [Results] Two Bacillus strains A8 and A9 demonstrating robust abilities of phosphorus solubilization, nitrogen fixation, and siderophore secretion were screened out from 83 Bacillus strains collected from the cotton field soil. strains A8 and A9 demonstrated remarkable IAA production, which reached 48.67 mg/L and 30.67 mg/L, respectively. Both strains were Gram-positive. The 16S rRNA gene sequence analysis identified strains A8 and A9 as B. spizizenii and B. halotolerans, respectively. The biocontrol efficacy of the composite microbial agent against cotton Verticillium wilt was evaluated. The composite microbial agent composed of strains Bs-Z15, A8, and A9 each at 1×10⁷ CFU/mL significantly reduced the disease index by 81.59% in pot experiments and 42.97% in field trials. Additionally, the agent enhanced the soluble sugar and chlorophyll content in cotton leaves, thus promoting cotton growth. [Conclusion] The composite microbial agent composed of strains Bs-Z15, A8, and A9 each at 1×10⁷ CFU/mL can control cotton Verticillium wilt while promoting cotton growth.

Abstract:[Background] The soil is rich in indoleacetic acid (IAA)-producing bacterial resources. The IAA they secrete can promote plant growth and improve soil fertility, and thus these bacteria represent natural biological fertilizer resources. [Objective] We studied the effects of IAA-producing bacteria on the growth and the seed yield and quality of Brassica napus L. in the field, as well as the physicochemical properties and enzyme activities in the soil, aiming to provide a scientific basis for the application of IAA-producing bacterial agents in improving the quality and yield of B. napus and enhancing the soil fertility. [Methods] After inoculation of the IAA-producing strains BTW20, BTW23, TJ8, KJ29, SG3-16, J1, and HJ in the root surrounding of B. napus, the growth status and seed yield and quality of B. napus and the physicochemical properties and enzyme activities in the soil were determined. The effects of IAA-producing strains on B. napus and soil quality in the field were evaluated. [Results] The six high-yield IAA bacterial strains BTW20, BTW23, KJ29, TJ8, SG3-16, and J1 were identified as Trabulsiella, Microbacterium, Sphingomonas, Priestia, and Ochrobactrum, respectively. Their IAA yields in shake-flask culture ranged from 110.11 µg/mL to 225.28 µg/mL within 72 h. The application of seven IAA-producing strains affected the growth and seed yield and quality of B. napus, as well as the physicochemical properties and enzyme activities in the soil, to varying degrees. Among them, strains TJ8, KJ29, and J1 increased the activities of urease, acid phosphatase, sucrase, and catalase by 12.01%–38.76%, 8.59%–23.89%, 18.48%–35.25%, and 7.68%–11.62% during the bolting stage and by 7.58%–25.26%, 8.54%–10.22%, 15.52%–22.89%, and 5.97%–9.81% at the maturity stage, respectively. J1 increased the plant height, root length, and underground dry weight by 90.24%, 40.36%, and 104.86% at the bolting stage and 18.43%, 34.81%, and 72.16% at the maturity stage, respectively. This strain increased the 1 000-seed weight and oil content of rapeseed by 11.17% and 6.06%, respectively, while decreasing the erucic acid by 72.44%, demonstrating the best quality-improving and yield-increasing effects. Correlation analysis showed that the erucic acid in rapeseeds had significantly negative correlations with the 1 000-seed weight and soil acid phosphatase activity. [Conclusion] IAA-producing bacteria have improving effects on the growth and seed yield and quality of B. napus and the physicochemical properties and enzyme activities in the soil, while the effects of different strains vary. This study screened out IAA-producing bacterial strains such as J1, providing strain resources and a theoretical basis for improving the quality and yield of B. napus in the field.

Abstract:[Background] Enterococcus faecalis is a major opportunistic pathogen that can cause infections in humans and various animals. However, due to its inherent drug resistance and the enhancing multi-drug resistance, the clinical treatment of E. faecalis infections faces severe challenges. [Objective] This study explored the effects of berberine (BBR) on the transcription of virulence factors and pathogenicity-related phenotypes of E. faecalis, aiming to provide a reference for the treatment of E. faecalis infections. [Methods] The two-fold dilution method was employed to determine the minimum inhibitory concentration (MIC) of BBR against E. faecalis N9. Subsequently, sub-inhibitory concentrations (1/2 MIC, 1/4 MIC, and 1/8 MIC) of BBR were used to treat E. faecalis N9. The transcription levels of virulence factors of E. faecalis N9 were determined by qPCR. Additionally, biofilm formation of the strain was evaluated through crystal violet staining, and the adhesion to the pig small intestinal epithelial cell line IPEC-J2 was analyzed via a cell adhesion test. A gelatin liquefaction test was conducted to examine the gelatin liquefaction ability of the strain. [Results] The MIC of BBR against E. faecalis N9 was 625 μg/mL. Treatment with sub-inhibitory concentrations (1/2 MIC and 1/4 MIC) of BBR significantly inhibited the transcription of fimbrium-related virulence factors (ebpA, ebpB, ebpC, ebpR, and rnjB), biofilm-related virulence factors (esp, ace, psr, srtA, and atn), and gelatin liquefaction-related virulence factors (fsrA, fsrB, fsrC, sprE, and gelE) of E. faecalis N9. Moreover, the treatment markedly reduced the biofilm formation, adhesion to IPEC-J2 cells, and the ability to liquefy gelatin of E. faecalis N9. [Conclusion] BBR could effectively inhibit the transcription of pathogenicity-related virulence factors as well as the biofilm formation, cell adhesion, and gelatin liquefaction of E. faecalis N9. These findings suggest that BBR might be a candidate for treating E. faecalis infections.

Abstract:[Background] Polyene macrolactams possess unique chemical structures and significant biological activities, such as antibacterial, antiparasitic, and anticancer effects, showing great potential for drug development. Accordingly, they have attracted considerable attention. [Objective] To discover new polyene macrolactams and their biosynthetic gene clusters from microbial resources through bioinformatics analysis combined with microbial genetics and natural product chemistry. [Methods] Firstly, antiSMASH was used to analyze the biosynthetic gene clusters for secondary metabolites in the genome of Micromonospora auratinigra DSM 44815, and a gene cluster likely involved in the synthesis of polyene macrolactams was identified. Next, homologous recombination was employed to knock out the core synthase gene within the gene cluster, and the obtained mutant strain was used for fermentation. Metabolites were analyzed by liquid chromatography to confirm the product of the gene cluster. Subsequently, the compound was isolated and purified, and its structure was determined by high-resolution mass spectrometry and nuclear magnetic resonance (NMR). Finally, the fermentation medium was optimized to increase the yield of the compound in shake-flask fermentation. [Results] A novel type I polyketide synthase gene cluster (mms cluster) was identified in the genome of M. auratinigra DSM 44815 through antiSMASH analysis, and it was predicted to be capable of synthesizing polyene macrolactams. High-resolution mass spectrometry of the fermentation broth detected a compound with a molecular weight of 427.272, which was suspected to be the product of this gene cluster. Subsequent isolation, purification, and NMR analysis confirmed this compound (named MMS-A) as a novel polyene macrolactam. The knockout of the type I PKS gene mmsB in the mms cluster by homologous recombination resulted in the loss of MMS-A production in the mutant strain, which confirmed that the biosynthesis of MMS-A depended on the mms cluster. On the basis of the compound structure and the predicted functions of the enzymes encoded by the gene cluster, a biosynthetic pathway for MMS-A was proposed. Finally, after optimization of the fermentation conditions, the yield of MMS-A was increased to 624.5 mg/L in the M4 medium. [Conclusion] We identified a new biosynthetic gene cluster in M. auratinigra DSM 44815 and preliminarily determined that the synthesized product, MMS-A, was a novel polyene macrolactam. The yield of MMS-A was successfully increased by optimizing the fermentation medium. This study enriches the chemical and biosynthetic diversity of polyene macrolactams and provides new molecular, strain, and biosynthetic component resources and tools for the future development of such compounds.

Abstract:[Background] The current misuse of antibiotics has exacerbated the issue of pathogen resistance, rendering marine microorganisms a focal point of research due to their novel bioactive metabolites. [Objective] a strain resistant to Candida albicans was screened and identified from the bacterial strains in the Arctic Ocean sediment. The fermentation conditions of this strain were optimized, and the antimicrobial activity of the crude fermentation extract was evaluated. [Methods] Among the strains from Arctic sea mud, a strain with the best antibacterial effect against Candida albicans was selected through the plate confrontation method and the agar diffusion method. With the diameter of the inhibition zone obtained by agar diffusion method as the indicator, single factor test, orthogonal test, and response surface method were employed to optimize the medium formula and fermentation conditions. The crude extract was obtained by fractional precipitation with hydrochloric acid and methanol extraction. The results of agar diffusion assay demonstrated inhibitory effects of the strain against six pathogens. [Results] A strain W52 with the strongest antibacterial effect against Candida albicans was identified as Bacillus subtilis. The optimal medium formula consisted of 5 g/L glucose, 1 g/L peptone, and 2 g/L NaCl, and the optimal fermentation conditions were fermentation at 36 ℃, initial pH 6.5, and 178 r/min for 75 h. After optimization, the diameter of the inhibition zone increased significantly from 18.43 mm to 30.23 mm. [Conclusion] B. subtilis W52 has inhibitory effects on C. albicans, Candida auris, Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, and Salmonella typhimurium. This study provides a theoretical basis for the development of antimicrobial agents derived from marine microorganisms.

Abstract:[Background] Listeria monocytogenes, recognized globally as one of the four major foodborne pathogens, poses a severe threat to public health through its induction of foodborne illnesses. Although only L. monocytogenes can cause human illnesses, the presence of non-pathogenic Listeria in food can serve as a potential contamination indicator, indicating the risk of cross contaminations with pathogenic strains. The available numerical identification methods and products for Listeria both domestically and internationally have shortcomings such as manual sample addition, cumbersome operation, a narrow identification spectrum (only for six species), and high costs. [Objective] To develop a semi-automatic and cost-effective biochemical kit based on the numerical identification methodology for identifying more species of Listeria. [Methods] On the basis of the established numerical identification system for Listeria, we designed and optimized the micro-formula of the biochemical matrix and developed a semi-automatic freeze-drying biochemical kit based on numerical identification. We then took matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS), API-Listeria, and 16S rRNA gene sequencing as the control methods to evaluate the identification performance of the developed kit. [Results] A total of 260 biochemical profiles of Listeria were obtained, with the overall identification accuracy of 99.23% at the species level. Twelve micro-biochemical reagents in the kit were capable of identifying 17 species of Listeria, and the biochemical tests were stable and reproducible. The cost (20 CNY/sample) of the kit developed in this study was only 15.4% that of the similar product (130 CNY/sample) from the Merieux (France). [Conclusion] The biochemical kit for Listeria developed in this study integrates numerical identification, semi-automatic biochemical reagents, and online analysis software, with high identification accuracy, easy operation, and a wide identification range.

Abstract:[Background] Bacteria of Staphylococcus are major pathogens in clinical infections. Different species of Staphylococcus cause varying degrees of harm to the human body. Therefore, typing of Staphylococcus provides a theoretical basis for precise treatment in clinical medicine. The existing typing techniques for different Staphylococcus species have disadvantages such as high costs, complicated operation, and low accuracy. Therefore, the conventional isolation and identification techniques are still mainly used at present. [Objective] To develop a simple and reliable biochemical typing method, establish a numerical identification system for Staphylococcus bacteria, and evaluate the identification performance of this system. [Methods] We integrated the biochemical reaction formulas required for the identification system into a set of injection molded parts to produce identification strips. A numerical identification system for Staphylococcus was constructed in combination with numerical identification software. The identification accuracy of the system was evaluated with Staphylococcus selectively isolated from agricultural trade samples as a reference standard and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) as the reference method. [Results] Biochemical tests were conducted on 370 strains of Staphylococcus in the training set, and a positive probability database of biochemical reactions for identifying 26 species/subspecies of Staphylococcus was created. The results were imported into the Identax software to construct a numerical identification system for Staphylococcus, and relevant standards were established to evaluate the identification results. The biochemical numerical identification of 422 isolates of Staphylococcus in the test set showed the result consistency rate of 91% with the MALDI-TOF MS method. [Conclusion] The numerical identification system for Staphylococcus that is developed in this study has simple operation, a low cost, and high accuracy. It can provide an experimental basis for primary-level laboratories and food safety testing and has good prospects for clinical application and promotion.

Abstract:Against the backdrop of the in-depth integration of educational information and intelligent technologies, conventional teaching models of Microbiology Experiment face challenges such as outdated teaching contents, lagging dynamic feedback, and single-dimensional evaluation criteria. In this study, we proposed an artificial intelligence (AI)-driven innovation framework to design personalized learning pathways and establish teaching plans based on foundational experiments and incorporating interdisciplinary collaboration, practical application, and innovative thinking cultivation. An intelligent diagnostic platform of experimental data was developed to precisely identify operational errors, data processing flaws, and analytical inaccuracy across experimental stages, enabling a closed-loop teaching mechanism of diagnosis-intervention-feedback. Furthermore, we constructed a dynamic evaluation system with a three-tier evaluation index system encompassing basic technical skills, innovative thinking, and scientific literacy, supported by multidimensional, visualized, and continuous evaluation methodologies. Practices have proved that this AI-participated teaching model significantly improves the course grades, teaching efficiency, and participation. The teaching reform effectively bridges the gaps between conventional teaching and practical needs, being of great significance for cultivating microbiology talents with innovative thinking and practical competency.