The starch-binding domains (SBDs) are structurally and functionally independent non-catalytic protein module widely found in carbohydrate active enzymes (CAZymes), and they play an important role in the degradation process of raw starch in ecological environment. In nature, SBDs effectively lead the catalytic domain to the substrate surface by specifically binding to starch granules or other polysaccharides, significantly enhancing the hydrolytic efficiency of enzymes. In addition to the non-hydrolytic disruptive activity on the structure of starch granules, SBDs widely influence many catalytic properties of host enzymes, including substrate specificity, environmental adaptability (thermostability, salt tolerance, and cold adaptation), and oligomerization state. These roles demonstrate their adaptive function in helping host microorganisms to compete for carbon sources in complex habitats. Here, we summarized the distribution characteristics, functional mechanisms, and multiple effects of SBDs on host enzyme functions in terrestrial and marine ecosystems. The main experimental methods for studying SBD functions, including domain deletion, functional characterization of binding and disruption, are also introduced. A broader and deeper understanding of SBDs enhances our knowledge of microbial competition for carbon sources in natural environments, as well as provides novel approaches for the rational design of industrial enzymes.

Biopolymers have significant influences and regulatory effect on microbial mineralization processes and precipitate characteristics. In this study, xanthan gum (XG) served as the biopolymer, and Klebsiella aerogenes was utilized as the carbonate mineralizing bacterium, the regulatory effects and mechanisms of XG concentrations on the precipitation yield, particle size, crystalline polymorph, and morphological characteristics of calcium carbonate precipitation induced by K. aerogenes were explored systematically. The results showed that when the calcium concentrations were 0.25 mol/L and 0.50 mol/L, and the XG concentrations were 0.50 g/L and 0.75 g/L, respectively, the precipitation yield of calcium carbonate was 25.00% and 9.60% greater than that of the control group, respectively. With the amount of XG addition increasing, at low calcium concentrations (0.25 mol/L), the proportion of calcite decreases and the proportion of vaterite increases, and gradually to be stabilizing. At high calcium concentration (0.50 mol/L), the proportion of calcite tends to increase first and then to decrease, whereas the proportion of vaterite tends to decrease and then gradually to stabilize. Compared with those of the control group, the average particle sizes of the calcium carbonate crystals in the two calcium concentrations groups decreased by 44.50% (0.25 mol/L) and 64.40% (0. 50 mol/L). Meanwhile, the addition of XG promoted the formation of spherical or spheroidal-like calcium carbonate morphology. These findings provide a new strategy for the precise and customized regulation of microbial mineralization.

In this study, fungal diversity was analyzed and antimicrobial activity isolates were screened from Eling Lake to enrich the fungi diversity in the extreme environment and to provide basic materials for subsequent development of biocontrol agents. Ten sediment samples were collected from shoreside of Eling Lake, and fungi were isolated by dilution separation method using seven selective mediums. The isolated fungi were identified by morphological characteristics and rDNA-ITS sequence phylogenetic analysis, and antimicrobial activity isolates were screened by confront culture method. One hundred and forty-four fungi isolates were obtained, belonging to totally 22 genera of Ascomycota, Mucoromycota and Zygomycota. Seven high antimicrobial activity isolates were screened from one hundred and forty-four fungi isolates, they had a broad spectrum of antimicrobial activity on eight fungi pathogens from maize, highland barley and wheat. Moreover, they were Phaeosphaeria and Emericellopsis, respectively. These results showed that sediment fungi resource in Eling Lake was abundant and have certain biocontrol and utilization value.

To reduce nitrogen loss during aerobic composting, enhance compost fertility, and minimize environmental pollution, this study used cattle manure as the material to isolate a highly efficient heterotrophic nitrifying strain of NB-2. Through morphological characterization and 16S rRNA gene sequence analysis, the strain was identified as Alcaligenes faecalis. Further research showed that NB-2 exhibited significantly enhanced ammonia oxidation capacity under the conditions of sodium citrate as the carbon source, C/N ratio of 15, temperature of 35 ℃, and pH of 9.0. The ammonia nitrogen () removal rate reached 100% at 32 hours, with a removal rate as high as 33.38 mg/(L·h). This study demonstrated the potential of strain NB-2 in composting applications to reduce nitrogen losses while improving fertilizer quality and efficiency, thereby promoting the sustainable development of the livestock industry.

In this study, we performed 16S rRNA high-throughput sequencing to examine the diversity of endophytic bacterial communities in Gymnadenia conopsea growing at four different locations on Mount Sejila. The results revealed that a total of 715 920 effective sequences were obtained from all samples, which were associated with 2 365 operational taxonomic units, classified within five phyla, 38 families, and 62 genera. Proteobacteria was identified as the dominant bacterial phylum and the predominant genera were Pseudomonas, Methylbacterium, and Sphingomonas. Diversity analysis revealed that among the collected samples, the stem samples（LHS）collected at the Linhai Observation Deck were characterized by the highest endophytic bacterial community richness, whereas the richness of fruit samples（LDF）collected from the Radar Station was the lowest. The stem samples（FMS）from the Abandoned Wood Factory site were found to have the highest diversity of endophytic bacterial communities, and the diversity indices of communities in the stems, leaves, and fruits of plants growing at this sampling point（FM）at a lower altitude were higher than those recorded at the other three sampling points. Among the four types of tissue collected, the richness of endophytic bacterial communities in the stems, leaves, and roots was higher than that in the fruits, and we found that the diversity and richness of endophytic bacterial communities in fruits declined with increasing altitude, with the values obtained for the endophytic bacteria in fruit pods（LDF）being the lowest. Furthermore, we detected significant differences in the diversity of endophytic bacterial communities in the same tissue in different habitats, whereas there were differences in the diversity of endophytic bacteria within the different tissues of plants growing in the same habitat. Principal coordinate analysis indicated that the composition of endophytic bacterial communities was influenced by environmental factors and tissue types, and redundancy analysis and correlation heatmaps provided evidence to indicate that total phosphorus, total potassium, pH, and altitude were the main influencing factors, significantly correlated with the composition of these endophytic bacterial communities. Moreover, PICRSt prediction analysis revealed that the endophytic bacteria in G. conopsea were mainly enriched in three primary metabolic pathways, namely, metabolism, environmental information processing, and genetic information processing, and the activity of most of the identified metabolic pathways was found to show a declining trend with increasing altitude. This study employed high-throughput sequencing technology to analyze the effects of environmental factors and tissue types on the diversity and community structure of endophytic bacteria in G. conopsea. It aims to enrich and improve the resources of endophytic bacteria in wild G. conopsea, laying a foundation for the future resource development of beneficial endophytic bacteria and the protection of wild G. conopsea.

To examine the impact of aerobic exercise training on the structures of gut microbiota in female drug addiction individuals, a 12-week aerobic exercise intervention was conducted with 100 female participants who have a history of drug dependence. Stool samples were collected from the subjects before and after the exercise intervention, and the composition of the gut microbiota before and after exercise was analyzed using high-throughput sequencing of the 16S rRNA gene in female addicted populations taking different types of drugs. The results indicate that a 12-week aerobic exercise intervention induces significant changes in the species diversity and abundance of dominant genera within the gut microbiota of female drug addiction individuals. The principal component analysis revealed significant difference in the structures of the gut microbiota between the traditional drug intervention group and the novel drug intervention group, both before and after exercise. At the class, order, and family levels, significant differences (P<0.05) were observed in species composition between pre-and post-exercise samples within the traditional drug intervention group (MC group). Specifically, there was a notable increase in the abundance of Actinobacteria at the class level and Coriobacteriaceae at the family level following exercise. In the novel drug intervention group (MX group), significant differences（P<0.05）were also noted at the family and order levels between pre- and post-exercise samples. Post-exercise, there was a marked increase in the abundance of Bifidobacteriaceae at the family level and Bifidobacteriales at the order level. This study offers a comprehensive gut microbiota reference for exercise interventions aimed at enhancing the physical and mental health of female individuals with drug addiction.

Zinc-azithromycin is commonly utilized for the prevention and treatment of COVID-19. The effect of zinc-azithromycin on gut microbiota in vitro was explored to provide a theoretical basis for its clinical application. The effects of zinc-azithromycin on gut microbiota community and short chain fatty acids were inspected via in vitro fermentation, metagenomic sequencing, and gas chromatography. The results indicated that Zinc-azithromycin increased the relative abundance of Klebsiella, Rahnella, Pantoea, and significantly decreased the relative abundance of Megamonas and Bifidobacterium. Zinc-azithromycin also significantly altered the metabolism pathway, the abundance of antimicrobial resistance genes, and the content of short chain fatty acids of the gut microbiota, which might potentially have negative effects on human health.

Microbial remediation methods are widely used because of their environmental friendliness and efficiency. Most microorganisms are in the Viable but Non-culturable (VBNC) state under natural conditions, and only about 1% of microorganisms can be purely cultured. Resuscitation-promoting factor (Rpf), a cellular active factor produced by bacteria, can promote the resuscitation of VBNC state bacteria to a culturable state. The generation mechanism of bacterial VBNC state, the function and biological activity of Rpf protein were reviewed in this paper. The application of Rpf in environmental remediation and its challenge difficulties were also discussed in order to provide new ideas for the development of microbial remediation technology.

Zinc uptake regulator (Zur) is a transcriptional regulator of the ferric uptake regulator (FUR) superfamily, which exists in the form of dimers or multimers in most bacteria. Zur contains a conserved DNA-binding domain and Zn²⁺-binding domain, the latter is essential for Zur to recognize and bind Zn²⁺. Zn²⁺ acting as a cofactor can change the conformation of Zur and affecting its DNA binding ability to regulate the expression of zinc transporter-related genes to maintain zinc homeostasis in bacteria. Increasing studies have shown that Zur can be involved in a wide range of metabolic pathways directly or indirectly. By regulating the expression of key genes involved in metabolic pathways, Zur helps bacteria to respond effectively to the external environmental changes, and it is an important component for the bacterial metabolic regulatory network. This article reviews the research progress of Zur in molecular structure, Zn²⁺ response regulation, regulation of bacterial secondary metabolism, toxicity production and stress response to help researchers gain a more comprehensive understanding and in-depth exploration of the potential functions of Zur in the complex process of bacterial metabolism regulation.

Bacterial biofilm (BF) refers to the biological community formed through bacterial attachment and subsequent secretion accumulation on various surfaces, such as soil, rock, and plant rhizosphere. In natural habitats, microorganisms commonly adopt a biofilm lifestyle as an adaptive strategy to navigate through dynamic and intricate environmental conditions. This paper mainly introduced the composition and formation process of bacterial biofilm, sorted out the ecological function of bacterial biofilm, reviewed the interaction mechanism of multi-species biofilm, and prospected the future research directions in this field. This article is expected to provide theoretical guidance for the application of bacterial biofilm in agricultural production and environmental protection.

Sphingan, a class of biopolymers with high-molecular-weight exopolysaccharides synthesized as secondary metabolites by Sphingomonas species, has garnered considerable attention due to their versatile functional properties and wide-ranging applications. This review offers a comprehensive exploration of the structure-function relationships of three representative sphingans, including Gellan Gum, Welan Gum, and Sanxan Gum, with a focus on their unique rheological behavior, gelation mechanisms, and bioactive characteristics. The influence of environmental factors, such as temperature, pH, and ionic composition, on their physicochemical properties is systematically analyzed, providing insights into their adaptive functionalities. To address production scalability challenges, this review outlines critical strategies for enhancing sphingan biosynthesis, encompassing strain improvement through mutagenesis and genetic engineering, metabolic pathway optimization, and fermentation intensification. A promising avenue for sustainable production is the utilization of agricultural and industrial waste streams as alternative carbon sources, which not only reduces costs but also aligns with circular economy principles. Furthermore, the review examines the applications of sphingans in food, pharmaceuticals, agriculture, and the petroleum industry, highlighting their broad industrial relevance. Future research directions are proposed, focusing on structural modifications, functional enhancements, and innovative applications in emerging high-value sectors. This review provides a comprehensive understanding of sphingans, connecting fundamental insights with practical advancements, and offers a foundation for their broader commercialization and application.

With the continuous advancement of new engineering education concepts, Environmental Microbiology, as an important interdisciplinary discipline, plays an important role in cultivating high-quality engineering and technical personnel with innovative ability and practical skills. Therefore, Tianjin College of University of Science and Technology Beijing has introduced instructional Design model, ADDIE teaching Design model is introduced, ADDIE is an acronym for analysis, design, development, implementation and evaluation. The aim is to improve the teaching quality and students' learning effect of Environmental Microbiology experiment course through systematic teaching design and implementation. Taking the undergraduate students majoring in environmental engineering of Tianjin College of University of Science and Technology Beijing as the target, the teaching reform is carried out by using ADDIE teaching design model combined with online platforms such as micro-assistant and virtual simulation. The research results demonstrate that the application of ADDIE teaching design model significantly improves students' experimental operation ability and problem-solving ability, and students' theoretical knowledge is more solid. It provides not only an effective reference for the teaching reform of environmental microbiology experiment course, but also a useful reference for the exploration of innovative teaching mode of other related courses.