Persulfidation plays a role in protein functioning and signaling, maintaining the physiological and metabolic balance of cells, protecting cells from oxidative stress, and regulating sulfur homeostasis. This article summarized the internal relationship of hydrogen sulfide, reactive sulfur species, and cysteine metabolism, expounded the mechanism of sulfur homeostasis regulation, and introduced the role of persulfidation in microbial sulfur homeostasis, providing new thoughts for the future research.

The roles of gut microbiota and its metabolites in the pathogenesis and rehabilitation of neurodegenerative diseases, gastrointestinal diseases, and musculoskeletal systemic diseases in the elderly are receiving increasing attention. Gut microbiota and its metabolites can regulate the functions of the cranial nervous system and the musculoskeletal system through various pathways, involving the immune, endocrine, and nervous systems. Conversely, the gut, brain, and musculoskeletal system can act on the intestinal system via inflammatory, metabolic, and mitochondrial pathways to regulate the gut microbiota. Accordingly, bidirectional signaling mechanisms are formedvia the gut-brain, gut-muscle, and gut-brain-muscle axes, which affect the organism health. This review summarizes that gut microbiota establishes gut-brain-muscle interconnections mainly through metabolites, intestinal permeability, and immune-neural pathways, providing new ideas for improving the brain neuroplasticity and muscle health.

Atopic dermatitis (AD) is a highly prevalent allergic skin disease characterised by recurrent attacks and severe itching. The pathogenesis of AD involves a variety of factors including genetic susceptibility, epidermal barrier dysfunction, microbiome dysbiosis, immune imbalance, and the environment, while the available therapeutic drugs have severe side effects and limited efficacy. Studies have demonstrated that gut microbiota, particularly probiotics, play a role in AD. Probiotics can alleviate AD symptoms by inhibiting pathogens, enhancing barriers, improving the intestinal environment, and balancing the Th1/Th2 immune response, among other mechanisms. In this review, we summarized the skin and intestinal microecological characteristics of AD patients and systematically elucidated the mechanisms of probiotics in alleviating AD from the pathogenesis and influencing factors of AD, aiming to provide theoretical support for probiotics in the treatment of AD and related allergic skin diseases.

Hepatitis E virus (HEV) is a major zoonotic pathogen that causes acute viral hepatitis worldwide. HEV has high genetic diversity, and the incidence of various genotypes or subtypes is strongly correlated with host species, geographic location, and prevention and control methods. HEV strains HEV-3, comprising 3a–3i subtypes, were present in Europe and America, whereas HEV-3 and HEV-4 were prevalent in Asia. The epidemic strains in China have evolved from HEV-1 to HEV-4. Recent studies have shown that gene recombination, amino acid mutations, and synonymous codon usage patterns are part of the mechanisms underlying HEV evolution. In particular, amino acid mutations are the main driving force for the continued prevalence of the virus. This paper reviews the classification, global epidemic characteristics, and evolutionary mechanism of HEV, aiming to provide a reference for the prevention and control of hepatitis E and vaccine development.

Adequate intake of probiotics helps in maintaining the homeostasis of the gut microbiota, which is of great significance for human intestinal health. However, probiotics are vulnerable to stress and necessitate stringent storage conditions in industrial settings, which pose challenges to the vitality maintenance of probiotics in transportation and shelf-life. Therefore, it is essential to develop the preparation process capable of protecting the high vitality of probiotics. Drying beneficial for sustaining probiotic vitality is often used to maintain the strain stability. Among the drying methods, freeze-drying is widely used. However, during the freeze-drying process, probiotics encounter environmental stress conditions, which lead to cellular damage and even death. Therefore, the freeze-drying protectants that can significantly improve probiotic survival rate have become a research hotspot in the industrial application of probiotics. This article systematically summarizes both the commonly used and the newly discovered protectants for freeze-drying of probiotics and elucidates their mechanisms of action. It provides an overview of the factors affecting cell viability post freeze-drying while outlining the prospective research directions of freeze-drying protectants. This review is expected to furnish theoretical substantiation for the development of freeze-dried probiotics with high vitality.

[Objective] This study aims to investigate the soil fungal community structure in the tea plantations of Heshan and explore the relationship between fungal community and soil physicochemical properties. [Methods] We employed high-throughput sequencing to analyze the soil fungal community composition of 49 rhizosphere soil samples collected from healthy and mismanaging tea plantations in Heshan. The redundancy analysis (RDA) was performed to analyze the effects of soil physicochemical properties on the fungal community structure. The pairwise Wilcoxon signed-rank test was performed to compare the fungal taxa between the two kinds of tea plantations. FUNGuild was used to predict the soil fungal functions. [Results] Basidiomycota,Mortierellomycota, andAscomycota were the three dominant phyla in the rhizosphere soil of tea plantations in Heshan. The mismanagement of tea plantations increased the relative abundance ofBasidiomycota, but significantly decreased the relative abundance ofMortierellomycota. The fungal richness, Chao1 index, and ACE index were significantly lower in the mismanaging tea plantation than in the healthy tea plantation. The total nitrogen, total phosphorus, available phosphorus, organic matter, and available nitrogen were the primary driving factors for the differences of soil fungal β diversity. The soil pH, total phosphorus, exchangeable Ca²⁺ and Mg²⁺, available phosphorus, and available potassium were significantly correlated with the fungal taxa. Compared with the healthy tea plantation, the mismanaging tea plantation showed decreased relative abundance of core fungal taxa but increased relative abundance of medium and rare taxa. Ten of OTUs was common between healthy and mismanaging tea plantations. The pathogens causing tea gray blight, i.e.,Pseudopestalotiopsis theae andFusarium keratoplasticum, were identified in the healthy tea plantation. The relative abundance of biocontrol fungi,Trichoderma spirale andT.atroviride, significantly increased in the mismanaging tea plantation. The mismanaging tea plantation demonstrated increased relative abundance of pathotrophic, pathotrophic- saprotrophic-symbiotrophic, and symbiotrophic fungi but decreased relative abundance of saprotrophic-symbiotrophic fungi. [Conclusion] We elucidated the relationship of management mode with fungal community composition and soil physicochemical properties, providing the insights into the prevention and control of pathogens infecting black tea and the screening of biocontrol fungi in Heshan.

[Objective] Streptococcus thermophilus is widely used in the dairy industry as a common starter for fermented dairy products such as yogurt and cheese. Most strains ofS.thermophilus are galactose-negative (Gal⁻) and unable to metabolize galactose and excrete it extracellularly, which results in an increase in the galactose content in fermented milk.S.thermophilus can be treated by chemical mutagenesis to metabolize galactose and then used to develop the fermented milk products with low galactose content. [Methods] We used nitrosoguanidine (NTG) to induce the mutation ofS.thermophilus IMAU80846. Furthermore, we measured the activities of β-galactosidase (β-Gal), galactokinase (GalK), pyruvate kinase (PK), and glucokinase (GK) in the wild-type and mutant strains ofS.thermophilus IMAU80846 and analyzed the amino acid sequences encoding these enzymes.S.thermophilus IMAU80846Y that could metabolize galactose was obtained. We performed whole genome sequencing of the mutant strain and measured the content of lactic acid, lactose, galactose, and glucose in the fermented milk products produced with the wild-type strain and the mutant strain. We then compounded the wild-type strain and the mutant strain withLactobacillus delbrueckii subsp.bulgaricus IMAU20450, respectively, and characterized the two groups of fermented milk products during fermentation and storage. Finally, we prepared a fermented milk product with low galactose content. [Results] S.thermophiles IMAU80846Y had higher activities of β-Gal and GalK and lower activities of PK and GK than the wild-type strain. The amino acid sequences and whole genome sequences showed that the mutant strain had mutations in the genes involved in carbohydrate metabolism. The HPLC results showed that the fermented milk produced with the mutant strain had lower content of lactose and galactose and higher content of lactic acid and glucose than that produced with the wild-type strain. Compared with the compound group with the wild-type strain, the compound group with the mutant strain improved the titration acidity, viable cell count, viscosity, and water holding capacity of fermented milk. [Conclusion] The mutagenesis with NTG changed the ability ofS.thermophilus IMAU80846 to metabolize galactose, and the mutant strain could be used to produce the fermented milk with low galactose content.

[Objective] The biofloc-based culture system (BFS) ofPenaeus vannamei is a new ecological shrimp production mode based on the concept of cultivating and regulating the microbial community in the aquaculture system. However, the characteristics and assembly processes of microbial communities in different habitats of the BFS remain unclear. [Methods] The 16S rRNA gene sequencing was employed to explore the bacterial community composition in three different habitats (water, bioflocs, and shrimp gut) of the BFS. SourceTracker and the neutral model were adopted to explore the characteristics and assembly processes of bacterial communities in different habitats. [Results] The bacterial community diversity and composition varied significantly in the three habitats, and the structures and composition of bacterial communities were similar between bioflocs and shrimp gut. SourceTracker results showed that 98.76% of bacterial taxa in the shrimp gut were sourced from bioflocs, and only 0.83% were derived from water.Ruegeria existed in all the three habitats, with the relative abundance of 1.72%, 7.34%, and 6.00% in water, bioflocs, and shrimp gut, respectively. The unique amplicon sequence variants (ASVs) showed the maximal number of 89 in water, mainly belonging toMariculis andOwenweeksia. Bioflocs contained 56 ASVs, which were mainlyRheinheimera. Only 10 ASVs were present in the shrimp gut, mainly belonging toRoseobacter. The bacterial communities in water, bioflocs, and shrimp gut were all fit to the neutral model, which indicated that the bacterial communities in the three habitats were dominated by the neutral process. [Conclusion] The microbial communities in different habitats of the BFS were significantly different, and the intestinal bacteria of shrimp mainly came from bioflocs. The assembly processes in the three habitats were dominated by neutral processes. The results provide a theoretical basis for regulating the microbial community in the BFS.

Pathogenic mycoplasma has the ability to invade host cells, which is a key mechanism to their pathogenicity. Functional proteins that mediate the entry of mycoplasma may serve as potential drug or vaccine targets. [Objective] To clone and express the LRR5 protein encoded byMBOVPG45_0564 inMycoplasmabovis and to explore its role in the invasion of host cells byM.bovis. [Methods] The NCBI database was used for the homology analysis ofMBOVPG45_0564, and the structure of LRR5 protein was predicted by the Discovery Studio Client system. After prokaryotic expression of LRR5 protein, the mouse polyclonal antibody was prepared, and the subcellular localization of LRR5 protein was observed by immunoelectron microscopy. The invasion ofM.bovis into embryonic bovine lung (EBL) cells after LRR5 antibody blocking was observed by plate counting and laser confocal microscopy. After conjugation of LRR5 protein to the surface of fluorescent microspheres, the entry of the microspheres into EBL cells was observed by laser confocal microscopy and a high-content live-cell imaging system. [Results] MBOVPG45_0564 was a conserved sequence inM.bovis and encoded LRR5, a membrane-associated protein with a typical crescent-like spatial conformation. Multiple repeating leucine motifs were assembled in a supercoiled manner to form a solenoid protein structural unit. After LRR5 antibody blocking, the invasion rate ofM.bovis to EBL cells reduced (P<0.05), and the fluorescent microspheres conjugated with LRR5 protein could successfully enter EBL cells. [Conclusion] The LRR5 protein encoded byMBOVPG45_0564 is localized on theM.bovis membrane and plays a role in the invasion ofM.bovis into host cells.

Equine coronavirus (ECoV) is an emerging virus attacking the gastrointestinal tract in horses, and the infected adult horses mainly present fever, abdominal pain, and diarrhea. In 1975, ECoV infection first appeared in the United States, and since then it has been prevalent in many countries and regions. Only one recombinant strain of ECoV was isolated from the small intestine of a donkey experiencing diarrhea in Shandong Province, China. [Objective] Understanding the genetic composition, genetic relationship, and biological characteristics of ECoV strains in China can lay a foundation for unveiling the epidemic status and genetic evolution trend of ECoV and provide materials for the research and development of products for the prevention and control of ECoV. [Methods] RT-PCR was employed to detect the stool samples from a horse experiencing diarrhea in Huangpi District, Wuhan City, Hubei Province. The virus was isolated from the positive samples and verified by indirect immunofluorescence assay (IFA) with monoclonal antibodies targeting the S1 protein of ECoV. Based on the whole genome sequencing results of the isolate, the phylogenetic analysis and sequence alignments of the whole genome, N gene, and NS2 gene were performed. [Results] An ECoV strain was successfully isolated and named ECoV-JL. Transmission electron microscopy (TEM) showed that the isolated virus particles were spheroidal and had a capsule membrane and a typical spiroid structure of coronaviruses. The tissue culture infectious dose 50% (TCID₅₀) of ECoV-JL reached a peak of 10^6.16 TCID₅₀/mL 72 h post infection in HRT-18 cells. ECoV-JL strains could infect three human cell lines: HRT-18 (human ileocecal cancer cells), Caco-2 (human colorectal adenocarcinoma cells), and Huh7 (human liver cancer cells). The genome sequence of ECoV-JL and the ECoV genome sequences in GenBank showed the similarity within the range of 97.9%–99.0%. ECoV-JL was in a separate branch of the phylogenetic tree and far related to other strains, which indicated that ECoV-JL might be derived from recombination mutations. The NS2 gene presented more mutations, and the difference in NS2 gene was the main reason for the poor homology between ECoV-JL and other strains. [Conclusion] We isolated and identified an ECoV strain from the stool samples of horses with diarrhea and named it ECOV-JL. The study about the biological characteristics and phylogenetic relationship of this strain reflected the characteristics of the epidemic strains in Hubei Province, providing a clue for the epidemic status and evolution trend of ECoV in China.