This study aims to determine the effects of Rhodobacter sphaeroides 8513 on the physiological and biochemical indicators, short-chain fatty acids, and gut microbiota of healthy BALB/c mice. Mice were divided into the control group and R. sphaeroides group (5×10 8 CFU/mL). After 28 days of continuous gavage, fecal samples were collected for high-throughput sequencing, then mice were sacrificed and the serum was taken for biochemical analysis. Liver, kidney, and spleen were obtained for organ coefficient calculation, and cecum contents were collected for short-chain fatty acid analysis by gas chromatography. The results showed that there was no significant difference in body weight gain, alanine aminotransferase (ALT) and urea nitrogen (BUN) levels between the control group and R. sphaeroides group, while R. sphaeroides significantly decreased the aspartate aminotransferase (AST) and creatinine (CRE) level. No side effect of R. sphaeroides treatment on the basic physiological health of mice was observed. R. sphaeroides significantly increased the content of acetic acids in the gut of mice, while there were no significant changes in the concentration of butyric and propionic acid. High-throughput sequencing analysis indicated that there was a significant difference in α-diversity between these 2 groups, while there was no significant difference in β-diversity between them. R. sphaeroides not only increased the abundance of anaerobic bacteria of Rhodospirillaceae, Desulfovibrionaceae, and Helicobacter in the gut of mice, but also increased the abundance of the predominant microflora in the gut such as Bacteroidaceae (Bacteroides), Prevotellaceae, Clostridiales_vadinBB60_group (Closporaceae). These results suggested that R. sphaeroides 8513 could modulate the microbial ecology in the gut of mice.

This study explored the effects of L. plantarum BW2013 on mucosal integrity and gut microbiota of mice with dextran sulphate sodium (DSS) induced colitis. The results show that the clinical symptoms in DSS modelled ulcerative colitis (UC) were improved by L. plantarum BW2013 via decreasing disease activity index (DAI) scores and suppressing inflammatory cell infiltration. Furthermore, L. plantarum BW2013 decreased the levels of diamine oxidase (DAO) activity, myeloperoxidase (MPO) and D-lactic acid (DLA). The mRNA expression of ZO-1, occludin and claudin-1 was upregulated by L. plantarum BW2013, which also increased IL-10 and reduced TNF-α, IL-1β and IL-6 in the colon. 16S rDNA sequencing showed that L. plantarum BW2013 enhanced α-diversity. L.plantarum BW2013 upregulated significantly the abundance of unidentfied_Lachnospiraceae, Lactococcus, Rikenella, Lactobacillus and Odoribacter, which had an inhibitory effect on inflammation and a protective effect on the integrity of the mucosa. These results demonstrate that L. plantarum BW2013 alleviates DSS modelled UC by protecting mucosal integrity and ameliorating the composition of gut microbiota.

Lactobacillus plantarum BW2013 was isolated from the fermented Chinese cabbage. This study aimed to test the effect of this strain on the gut microbiota in BALB/c mice by 16S rRNA amplicon sequencing. The mice were randomly allocated to the control group and three treatment groups of L. plantarum BW2013 (a low-dose group of 108 CFU/ml, a medium-dose group of 109 CFU/ml, and a high-dose group of 1010 CFU/ml). The weight of mice was recorded once a week, and the fecal samples were collected for 16S rRNA amplicon sequencing after 28 days of continuous treatment. Compared with the control group, the body weight gain in the treatment groups was not significant. The 16S rRNA amplicon sequencing analysis showed that both the Chao1 and ACE indexes increased slightly in the medium-dose group compared to the control group, but the difference was not significant. Based on PCoA results, there was no significant difference in β diversity between the treatment groups. Compared to the control group, the abundance of Bacteroidetes increased in the low-dose group. The abundance of Firmicutes increased in the medium-dose group. At the genus level, the abundance of Alloprevotella increased in the low-dose group compared to the control group. The increased abundance of Ruminococcaceae and decreased abundance of Candidatus_Saccharimonas was observed in the medium-dose group. Additionally, the abundance of Bacteroides increased, and Alistipes and Candidatus_Saccharimonas decreased in the high-dose group. These results indicated that L. plantarum BW2013 could ameliorate gut microbiota composition, but its effects vary with the dose.

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