Abstract:Gut microbes play an important role in maintaining human health and inducing disease development. The glycosylation modification of gut microbes has a profound impact on the host’s life activities. From the perspective of glycomics, this review discusses and analyzes the composition and function of gut microbes, the glycosylation patterns of representative bacteria and their closely related physiological functions. We aslo summarize the regulation ways of glycosylation on gut microbial functions and activities.

Abstract:Rare sugars, referred to their limited existence of rare monosaccharides and their derivatives in nature, can be applied in many areas ranging from foodstuffs to pharmaceutics and nutrition, or as raw materials for various natural products and drug candidates. However, most of the rare sugars are quite expensive, and their synthetic chemical routes are both limited and economically unfeasible due to expensive raw materials. Meanwhile, due to the advantages of enzymatic techniques such as moderate reaction conditions, high specificity, efficiency, and sustainability. Therefore, enzymatic transformations have become a very powerful tool in this field. This article reviewed the biological functions and applications of rare sugar, including D-tagatose, D-allulose, D-sorbose, L-fructose, and D-allose. Meanwhile, this article reviews the studies on the enzymes for rare sugar production and its enzymatic production.

Abstract:Peroxisome is an organelle with single membrane in various eukaryotic cells, and contains various enzymes essential for multiple physiological and metabolic processes in organisms. At present, more than 30 proteins that control peroxisome assembly, division, and inheritance are identified from fungi, named peroxins (encoded by PEX genes). Peroxins are also involved in glyoxylate cycle and in fatty acid metabolism, and related closely with the pathogenicity of fungi. Recently, peroxins have been identified from increasing number of fungi with the development of genome sequencing technology, as well as the application of novel experimental technology. In this review, we summarized the category and distribution of peroxins, and discussed the properties and functions of peroxins in fungi.

Abstract:Gas vesicles (GVs) are intracellular organelles with a rigid hollow structure completely composed of proteins. It can provide buoyancy for aquatic microorganisms, and is very important for their survival under adverse environment or stress conditions. In recent years, GVs with diverse functions in nonaquatic microorganisms such as Serratia and Streptomyces have also been reported. Gas vesicle biosynthetic gene clusters in different bacteria have presented distinct characteristics, as well as the corresponding regulation mechanisms for GVs biosynthesis. This review summarizes the basic characteristics of GVs from various bacterial species, including their fundamental physiological functions, biosynthetic and regulation mechanisms, as well as the applications of GVs in biotechnology. Finally, the biosynthetic studies of GVs in important industrial microorganism Streptomyces, and the potential applications of recombinant GVs are prospected.

Abstract:[Background] Quorum sensing inhibitor (QSI), promising alternatives to antibiotics, can reduce the infectivity and virulence of pathogenic bacteria by interrupting quorum sensing pathways. Desert soils contain rich actinomycetes, which are an important source for the mining of QSI. [Objective] To investigate the bacterial diversity in the soil from Kumutag Desert and screen out the actinomycetes with the quorum sensing inhibitory activity. [Methods] Illumina NovaSeq high-throughput sequencing was employed to reveal the composition of bacterial community in the soil of Kumtag Desert, and the culture method to isolate the actinomycetes. The Chromobacterium violaceum 026 model was used for the screening of the actinomycetes with quorum sensing inhibitory activity. The functions of the strains screened out were initially evaluated. [Results] The soil samples harbored 150 genera of bacteria belonging to 96 orders of 23 phyla. The dominant phyla were Proteobacteria (61%) and Actinobacteria (28%). As for Actinobacteria, the genus with the highest relative abundance was Mycobacterium (87.3%), followed by Rhodococcus (6.8%) and Cutibacterium (0.9%). A total of 108 isolates were obtained and identified as actinomycetes belonging to 10 genera of nine families, in which the dominant genus was Streptomyces (65.76%). Thirteen strains with quorum sensing inhibitory activity were screened out, including 10 strains of Streptomyces and each one strain of Nocardiopsis, Bailinhaonella, and Kibdelosporangium. Strain Streptomyces sp. D67 exhibited broad-spectrum antimicrobial activities. [Conclusion] The bacteria in the soil of Kumutag Desert have high diversity and contain multiple strains of actinomycetes with quorum sensing inhibitory activity. Several strains with quorum sensing inhibitory activity demonstrate strong antimicrobial activity, which provide strain resources for the subsequent development of natural QSI and antimicrobial agents and lay a theoretical foundation for the development of biopharmaceuticals and biocontrol.

Abstract:Brucella is a genus of globally widespread zoonotic pathogens capable of infecting wild animals, domestic animals, and humans. To establish and sustain chronic infections within the host, Brucella have evolved multiple strategies to evade host immune responses and extensively replicate in host cells, which primarily rely on the type Ⅳ secretion system (T4SS) and its secreted effectors. The T4SS functions by directly injecting effectors into host cells, modulating various host cell functions to help the pathogen evade immune surveillance, manipulate the intracellular environment, and promote its survival and replication. This article reviews the structure and function of the Brucella T4SS and the latest research progress in the role of Brucella T4SS effectors in regulating host cell functions, exploring how bacteria of Brucella manipulate host cell signaling pathways to control intracellular vacuole dynamics and establish a replicative niche conducive to bacterial survival. These advancements provide new insights into the pathogenesis of Brucella infections and aid in the development of more effective strategies for preventing and treating Brucella-related diseases.

Abstract:[Background] Colletotrichum graminicola, one of the main pathogens infecting maize, causes serious economic losses and directly threatens the global food security every year. Velvet proteins are fungal unique proteins with conserved functions, playing a role in regulating the growth and development of fungi. [Objective] To study the biological functions of a Velvet protein CgrVosA identified from C.graminicola. [Methods] The CgrvosA-knockout mutant and complementary strain were constructed by homologous recombination. The vegetative growth, stress response, conidial yield, germination, and pathogenicity of the strains were determined and compared to reveal the functions of CgrVosA. [Results] CgrvosA encoded a 425-residue protein with a typical Velvet protein domain. Compared with the wild type, ΔCgrvosA exhibited slow growth, high sensitivity to NaCl and H2O2, enlarged oval conidia, and reduced yield and germination rate of oval conidia. [Conclusion] The Velvet protein CgrVosA is involved in the regulation of vegetative growth, response to hyperosmotic and oxidative stress, and oval conidial production and germination of C.graminicola.

Abstract:Legionella pneumophila (L. pneumophila) is a distinct model for pathogen-host interaction research. Its unique secretion systems as well as the structures and functions of their substrate effectors are the research hotspots in the field of pathogenic microorganism. Type Ⅱ secretion system (T2SS) plays a major role in promoting bacterial survival in the environment and in human hosts, and Legionella secretion pathway (Lsp) is a typical T2SS in Gram-negative pathogens. This review briefly summarizes the research progress of L. pneumophila T2SS and its substrate effectors, emphasizing on their structures and functions, so as to provide in-depth understanding of the function and mechanism of T2SS in Gram-negative pathogens.

Abstract:Toxin-antitoxin (TA) system is prevalent in chromosomes and mobile genetic elements of bacteria and archaea. TA systems are diverse in structure and function, which are currently classified into eight types (type I-VIII). They are involved in biofilm formation, virulence, drug-resistant infection of host bacteria, regulation of plasmid copy number, and maintenance of prophage after its excision. In this paper, we reviewed the latest classification and functions of TA systems and the regulatory functions of antitoxin, and then briefly described the application of TA systems.

Abstract:[Objective] The result of this study will provide evidences for the exploration and utilization of plant endophyte from Stipa capillata on alpine meadow, and provide a valuable resource for the study of biological fertilizer. [Methods] This test exploited the conventional methods of separation of endophytic bacteria 265ZY4 from Stipa capillata, and the strain was studied by 16S rRNA sequence analysis and biological characteristics including antibacterial activities, IAA secretion, phosphate solubilization and nitrogen fixation by using in vitro antagonistic tests, Salkowski colorimetry and Mo-Sb colorimetry. [Results] Strain 265ZY4 demonstrated inhibitory activities to three fungal pathogens of potato, the best inhibitory rate of the strain were 83.03% against Colletotrichum coccodes. IAA was secreted by 265ZY4 as high as 9.30 mg/L in the King medium without addition of tryptophan, The strain also possessed the capacity of phosphate solubilization and without the capacity of nitrogen fixation. With the cultural and morphological characteristics, combined with 16S rRNA sequence analysis, the strain 265ZY4 was identified as Bacillus subtilis. [Conclusion] Strain 265ZY4 was preliminarily identified as B. subtilis, and has the good biological function. It should be an interesting isolate for developing agriculture.