Lactococcus lactis, a major starter culture in the dairy industry, has been widely applied in food fermentation. While current research has primarily focused on evaluating its role during fermentation, genomic investigations into its genetic diversity and functional adaptability remain limited. In this study, 199 L. lactis strains isolated from Chinese traditional artisanal cheeses (72 bovine, 71 goat, and 56 yak milk cheese isolates) were subjected to comparative genomic analysis. Genomic characteristic analysis indicated that bovine milk strains possess larger genomes and the highest number of unique genes. Functional characterization further demonstrated notable differences in carbohydrate metabolism among strains from different sources, with yak milk strains enriched in enzymes involved in complex polysaccharide degradation, including members of the carbohydrate esterases family. Moreover, strains from different sources exhibit distinct strategies for lactose hydrolysis and metabolic utilization, reflecting adaptive evolution to their specific nutritional niches. Analysis of the antibiotic resistance profile suggests that L. lactis predominantly harbors glycopeptide and lincosamide resistance genes, encompassing four distinct resistance mechanisms. Collectively, this study reveals the genetic diversity and adaptive evolution of L. lactis strains from different sources and identifies key genes associated with carbohydrate degradation, lactose metabolism, and antibiotic resistance, providing concrete genetic evidence for the selection of efficient and safe industrial fermentation strains.

Turicibacter sanguinis (T. sanguinis) is a prominent genus within the mammalian gut microbiota and is associated with various metabolic and gastrointestinal disorders, including overweight, obesity, irritable bowel syndrome (IBS) and constipation. However, the specific roles of T. sanguinis in host physiology remain unclear. In this study, antibiotic intervention experiments in mice revealed that T. sanguinis abundance was significantly reduced by intervention with sisomicin sulfate, ribostamycin sulfate, and cefadroxil, providing a T. sanguinis-depleted model for further investigations. By analyzing 6040 gut metagenomes, we observed an enrichment of T. sanguinis in IBS patients, while its abundance was significantly decreased in individuals with constipation. Next, using a T. sanguinis-depleted mouse model, we further validated the functional role of T. sanguinis in alleviating loperamide-induced constipation. Analysis of short-chain fatty acid (SCFA) and metabolomics revealed that T. sanguinis supplementation increased the levels of butyrate and isobutyrate in the colon and enhanced tryptophan metabolism, particularly elevating 5-hydroxytryptamine (5-HT) levels in intestinal tissue. Together, our findings identify T. sanguinis as a microbial mediator in antibiotic-associated constipation and offer new insights into microbiota-targeted therapies for functional gastrointestinal disorders.

The present study focused on the association between Bifidobacterium bifidum and host aging, aiming to evaluate the role of B. bifidum CCFM1359 in mitigating D-galactose-induced aging of mice through behavioral experiments, immunological assays, gut microbiota characterization and metabolomic analysis. The results showed that the supplementation of B. bifidum CCFM1359 significantly ameliorated D-galactose-induced cognitive decline including learning and memory capacity in mice, increased the activities of the antioxidant enzymes catalase (CAT), glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD), and decreased the levels of malondialdehyde (MDA) and the pro-inflammatory factors interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). The 16S rRNA gene sequencing of the fecal bacterial community demonstrated that the mitigating effect of B. bifidum CCFM1359 on aging was associated with increased relative abundance of beneficial genera including Dubosiella and Faecalibaculum and decreased abundance of the pro-inflammatory genus Turicibacter. Fecal metabolomics revealed that CCFM1359 intervention increased the levels of anti-aging metabolites such as melatonin, taurine, and deoxycholic acid. Microbe-metabolite interaction network analysis revealed that differential genera such as Romboutsia were positively correlated with deoxycholic acid, while others such as Christensenellaceae_uncultured showed negative correlation with melatonin and deoxycholic acid. These results indicated that B. bifidum CCFM1359 effectively alleviated host aging through improved cognitive function, anti-inflammatory and antioxidant effects, and restoration of gut microbiota homeostasis and associated metabolic dysregulation.