Nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR) are two precursors of the redox coenzyme nicotinamide adenine dinucleotide (NAD). Due to their ability to effectively increase NAD levels without toxic side effects, they have garnered significant attention. [Objective] This study employed an integrated approach combining metabolomics and 16S rRNA gene sequencing to investigate and compare the effects of NMN or NR supplementation on growth performance, intestinal health, gut microbiota, and metabolites in mice. [Methods] Male C57 mice were randomly allocated into a control group and two experimental groups. The experimental groups received drinking water supplemented with NMN or NR via gavage. Non-targeted metabolomics analysis and 16S rRNA gene sequencing were conducted to systematically investigate the alterations in endogenous metabolites and gut microbiota composition. Furthermore, the expression levels of associated factors were quantified by PCR. [Results] Compared with the control group, supplementation with NMN or NR increased the richness and diversity and improved the composition of gut microbiota in mice, with NMN showing greater efficacy. Additionally, both NMN and NR supplementation significantly upregulated the expression levels of metabolites associated with anti-inflammatory and antioxidant activities. PCR results indicated that both NMN and NR suppressed the expression of pro-inflammatory cytokines. Furthermore, NMN supplementation significantly increased the number of goblet cells in the colon, thereby enhancing the intestinal barrier function. [Conclusion] Dietary supplementation with NMN or NR improves the gut microbiota composition in mice, elevates the levels of beneficial metabolites, and inhibits the expression of pro-inflammatory cytokines.

Obligate symbiotic bacteria in the human gut play a key role in maintaining microecological balance and are generally thought to be transmitted vertically across generations through breastfeeding. However, compared with that on Bifidobacterium, there is limited literature on the transmission and diffusion mechanisms of Bacteroides, a representative of obligate symbiotic microbiota in the human body, within populations. Additionally, the occurrence and cross-generational transmission of Bacteroides within families remain poorly understood. [Objective] We explored the vertical transmission and co-occurrence patterns of Bacteroides among family members, aiming to reveal the assembly mechanism of gut microbiota in the human body and provide a theoretical basis for the recommendation of microbiome-based interventions and the realization of personalized gut regulation. [Methods] A high-throughput sequencing dataset for Bacteroides-specific rpsD in fecal samples from four families with 50 members in 3-4 generations in Xinjiang, China was established. Then, the composition and diversity of Bacteroides communities among different families and member groups were measured at the species level and amplicon sequence variant (ASV) level by comparison and annotation. [Results] A total of 16 Bacteroides species and 3 704 ASVs were identified, of which 1 293 ASVs were common among the four families. The five species with the highest number of ASVs were B. fragilis (653), B. ovatus (619), B. uniformis (507), B. caccae (463), and B. finegoldii (314), which were also the five species with the highest relative abundance and prevalence. There were significant differences in community composition and abundance of Bacteroides among families, with B. fragilis, B. uniformis, and B. faecichinchillae being the most significant representatives. There was no significant difference in alpha or beta diversity among family members grouped according to gender and age (P>0.05). By contrast, the beta diversity analysis based on Bray-Curtis distance showed differences between families (P=0.001). According to the sharing rate of ASVs and Bray-Curtis distance, the Bacteroides strain similarity of mother-child and siblings was significantly higher than that of father-child, couple, and unrelated members. [Conclusion] The community structure and diversity of Bacteroides were characterized by family convergence, with significant differences among families. The similarity of Bacteroides strains was the highest within the mother-child and sibling groups among different social relationship groups, supporting transgenerational vertical transmission at the strain level. The conclusion remains to be validated by the combination of the strain isolation method and metagenomic sequencing.

[Objective] To achieve efficient expression of the alkaline laccase PIE5 in Coprinopsis cinerea with molasses as a substitute for glucose as the carbon source. [Methods] We enhanced the laccase production in C. cinerea by either exogenous addition of the invertase GspInv or endogenous co-expression of GspInv to hydrolyze sucrose in molasses. The fermentation conditions were optimized based on the laccase activity. [Results] With 40 g/L molasses as the carbon source, strain CcPIE5-14 achieved the laccase activity of (11.9±1.2) U/mL, while sucrose remained unutilized in the fermentation liquid. Upon addition of exogenous GspInv, sucrose in the fermentation liquid was hydrolyzed into fructose and glucose, and strain CcPIE5-14 exhibited the peak laccase activity of (14.8±0.7) U/mL in the medium with 30 g/L molasses. Co-expression of GspInv in CcPIE5-14 generated the engineered strain CcPIE5-14-GspInv-12, which demonstrated the maximum laccase activity of (28.1±2.4) U/mL in the mKjalke medium. When using molasses as the carbon source for laccase production, strain CcPIE5-14-GspInv-12 achieved the peak laccase activity of (20.1±2.7) U/mL, which represented a 2.24-fold increase over that of the parental strain CcPIE5-14. Following fermentation condition optimization, strain CcPIE5-14-GspInv-12 attained the maximum laccase activity of (44.6±2.6) U/mL, which marked a 2.22-fold enhancement over the pre-optimization level. [Conclusion] The engineered strain CcPIE5-14-GspInv-12, co-expressing laccase and invertase, demonstrates efficient production of the alkaline laccase PIE5 in C. cinerea with cost-effective molasses as the carbon source.

UvrY is a key response regulator of the BarA/UvrY two-component system (TCS) and plays an important role in regulating bacterial virulence and environmental adaptability. [Objective] To investigate the regulatory role of UvrY in the biological characteristics and pathogenicity of Vibrio parahaemolyticus SH112. [Methods] The uvrY-deleted mutant (ΔuvrY) and its complementary strain (CΔuvrY) were constructed by homologous recombination. Phenotypes were systematically compared among the wild type, mutant, and complementary strains by growth curve plotting, motility (swimming and swarming) assays, biofilm formation assay, bacterial competition assay, HeLa cell adhesion and cytotoxicity assays, as well as a mouse infection model (analysis of bacterial loads in tissues and lethality). [Results] Compared with the wild type strain, ΔuvrY exhibited significant growth defects during the late exponential phase and weakened motility, with swimming and swarming reduced by 33% and 70%, respectively, while the biofilm formation of the mutant remained unaffected. Additionally, ΔuvrY showed weakened competitive inhibition against Escherichia coli, a 36.7% reduction in HeLa cell adhesion, and a 15.8% decrease in cytotoxicity. Mouse infection experiments further demonstrated that ΔuvrY had significantly reduced tissue colonization capacity and the attenuation of 75% in pathogenicity. [Conclusion] This study reveals that UvrY plays a crucial role in the pathogenicity of V. parahaemolyticus by regulating the growth, motility, competitive ability, and interaction with the host, giving insights into the regulatory network of the BarA/UvrY two-component system.

Saline-alkali soil is extensively distributed in the Songnen Plain of Northeast China, posing a major constraint on the grain yield. It has been demonstrated that endophytic bacteria of plants could promote plant growth and enhance plant tolerance to environmental stress. Agastache rugosa had been experimentally verified to exhibit strong salt tolerance. [Objective] To isolate and screen salt-alkali-tolerant endophytic bacteria from A. rugosa grown under high-salinity conditions and explore microbial resources for promoting plant growth under stress. [Methods] A. rugosa seedlings surviving under 200 mmol/L NaCl were selected to isolate endophytic bacteria by the tissue culture method. Salt-alkali tolerance of the endophytic bacteria was assessed by plate assays, and the plant growth-promoting and antimicrobial properties were also evaluated. [Results] A total of 95 endophytic bacterial strains were isolated from the leaves, stems, and roots of A. rugosa seedlings, of which 20 strains tolerated 15% NaCl and 14 strains could grow at pH 10.0. The selected elite salt-tolerant strains possessed plant growth-promoting properties such as indole-3-acetic acid (IAA) synthesis, siderophore production, and nitrogen fixation. Additionally, 18 strains showed resistance against three plant pathogens. The principal component analysis on plant growth-promoting properties, salt tolerance, and antimicrobial properties screened out strains YL-14, YS-35, and YR-18, which were molecularly identified as Bacillus sp. Under different salt stress conditions, three bacterial strains demonstrated significant growth-promoting effects on A. rugosa seedlings. Specifically, under 100 mmol/L salt stress, YL-14, YS-35, and YR-18 increased the seed germination rate by 5.5%, 8.5%, and 7.0% and the fresh root weight by 34.9%, 124.0%, and 127.0%, respectively. Strains YS-35 and YR-18 increased the main root length by 40.9% and 49.5%, respectively. [Conclusion] Endophytic bacterial strains YL-14, YS-35, and YR-18 with strong saline-alkali tolerance and plant growth-promoting properties were isolated from A. rugosa. These strains show great potential for development as bioinoculants and application in other crops to enhance crop stress resistance and growth, serving as new microbial resources for the utilization of saline-alkali soil.

[Objective] To investigate the role of Listeria monocytogenes LPXTG motif-anchored protein Lmo0130 in infection causing diseases, the bacterial growth, infection in cell and host among the L. monocytogenes wild-type, lmo0130-deleted and lmo0130-complementary strains were compared. [Methods] The lmo0130-deleted strain Δlmo0130 and lmo0130-complementary strain CΔlmo0130 were constructed to investigate the effects of Lmo0130 on the abilities of bacterial growth, cell surface adhesion and invasion, intracellular proliferation, intercellular migration, survival of infected mice, and bacterial load in mouse organs, ultimately demonstrated the role of L. monocytogenes Lmo0130 in cell and host infection. [Results] LPXTG motif-anchored protein Lmo0130 contributed to cell surface adhesion and invasion, intracellular proliferation, specific colonization in the liver and spleen, and pathogenicity in mice. However, it had no effect on bacterial growth or intercellular migration. [Conclusion] Lmo0130 contributes to cell and host infection of L. monocytogenes finally.

[Objective] To establish a triple qPCR detection method for Mycoplasma bovis, Pasteurella multocida (P.m) and Mannheimia haemolytica (M.h), and to conduct an epidemiological investigation of bovine respiratory disease complex (BRDC) in large-scale dairy farms with it. [Methods] Sensitive quality control samples were prepared using the purified strains isolated and identified in our laboratory. The conserved genes of the major prevalent strains in China were used as targets, including the uvrC of M. bovis, Kmt1 of P.m, and lktD of M.h, to establish a multiplex qPCR containing multiple pairs of primers and probes. By optimizing the parameters of the reaction system, a triple qPCR method was established and its sensitivity, repeatability and specificity were verified. The coincidence rate with the bacterial isolation and identification method was verified. A total of 1 252 clinical samples suspected of BRDC were tested using the established method, and the prevalence and spatiotemporal distribution characteristics of three pathogens were analyzed based on the test results. [Results] The R² values of the standard curves for the triple qPCR for detecting M. bovis, P.m, and M.h were 0.998 6, 0.994 6 and 0.998 6 respectively; the minimum detectable quantities were 2.50×10³, 1.26×10³ and 7.50×10² CFU/mL, respectively. The intra-batch and inter-batch coefficients of variation of the reaction system were both less than 2%, and only the specific amplification curves were observed for the three sensitive quality control samples established. The results of the test showed that the concordance rates of M. bovis, P.m, and M.h with bacterial isolation and identification methods were 100.00%, 98.40% and 97.60%, respectively. The epidemiological survey indicated that the total positive rate of bacterial pathogens in BRDC was 75.9% (95% confidence interval (CI), 73.4%-78.3%), among which the proportion of mixed infections was 48.8%. The incidence was higher in winter, and the positive rate in the northern region was significantly higher than that in the southern region (P<0.001). [Conclusion] The multiple qPCR method established in this study demonstrated excellent specificity, stability and repeatability, which provided a candidate solution for the detection of major pathogens of BRDC in China. The analysis of the co-infection characteristics and geographical-seasonal distribution patterns of BRDC bacterial pathogens offered meaningful references for the formulation of precise prevention and control strategies.

Streptomyces is a genus of diverse actinomycetes known for producing antibiotics, showcasing high value for research and development. However, the limited number of Streptomyces species included in commercial databases restricts the application of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) in the identification of Streptomyces. [Objective] To establish a MALDI-TOF MS database for the identification of Streptomyces based on the mining of whole genome sequencing data and test its accuracy. [Methods] By searching against a genome database, we selected all the genome-sequenced type strains of Streptomyces. Subsequently, the sequences of 12 ribosomal proteins were extracted from their genome sequences and theoretical MALDI mass/charge (m/z) values were calculated. Accordingly, a database was established based on the combination of 12 theoretically calculated m/z values, which can be used as the identification criteria for Streptomyces species. Finally, type strains were randomly collected for MALDI-TOF MS testing. To test the accuracy of the database construction method and comparison results, we matched the experimental m/z values with the theoretically calculated m/z values of the species in the database. [Results] We established a MALDI-TOF MS database including 615 Streptomyces species. The mass spectra of the tested strains were accurately matched with those of corresponding species in the database. In addition, we proposed a method for the identification of Streptomyces by database comparison. [Conclusion] The database established in this study laid a foundation for identifying Streptomyces based on MALDI-TOF MS.

[Objective] To investigate the antimicrobial resistance phenotypes and genomic characteristics of Salmonella Wandsworth isolates from fecal and bedding samples across four dairy farms in Jiangsu. [Methods] Serotyping was reconfirmed by the slide agglutination method, and antimicrobial susceptibility was determined via the Kirby-Bauer disk diffusion assay. Whole-genome sequencing was performed, followed by bioinformatics analysis to characterize multilocus sequence typing (MLST) profiles, antimicrobial resistance genes, and virulence genes. A phylogenetic tree was built based on core genome single nucleotide polymorphisms (SNPs) to assess genetic homology among strains and elucidate population evolutionary relationships between prevalent strains from diverse sources. [Results] Seven Salmonella Wandsworth isolates were identified, all exhibiting susceptibility to 14 tested antimicrobials. The isolates were identified as ST1498 by MLST, harboring the aminoglycoside resistance gene aac(6')-Iaa and 106 virulence genes spanning eight functional categories. The analysis of SNPs revealed high genetic homogeneity, with six isolates clustering closely and three isolates showing a difference of zero in SNPs. [Conclusion] This study isolated a rare ST1498-type Salmonella Wandsworth from dairy farms in Jiangsu. The isolates demonstrate susceptibility to all tested antimicrobials while harboring a resistance gene and multiple virulence genes. These findings highlight the necessity of enhanced Salmonella surveillance in dairy farms to mitigate potential epidemiological risks.

Colorectal cancer (CRC) remains a focal point of research due to its consistently high incidence and mortality, as well as the substantial economic and healthcare burdens it imposes. In recent years, the pivotal role of the gut microbiota in the prevention, diagnosis, and treatment of CRC has garnered increasing attention, offering promising avenues for the management of advanced stages of the disease. This article comprehensively reviews the involvement of the gut microbiota in the development and progression of CRC, elucidating the underlying mechanisms. Furthermore, it examines the potential applications of the gut microbiota in the systemic treatment of advanced CRC, with the aim of proposing novel strategies and insights to enhance the diagnosis and treatment of advanced CRC.