AUTHOR=Chen Benhao , Zhou Yi , Duan Lixiao , Gong Xuemei , Liu Xingmei , Pan Kangcheng , Zeng Dong , Ni Xueqin , Zeng Yan 

TITLE=Complete genome analysis of Bacillus velezensis TS5 and its potential as a probiotic strain in mice

JOURNAL=Frontiers in Microbiology

VOLUME=Volume 14 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1322910

DOI=10.3389/fmicb.2023.1322910

ISSN=1664-302X

ABSTRACT=In this study, the genome of Bacillus velezensis TS5, a fiber degrading strain isolated from Tibetan sheep, was characterized and its digestive and antioxidant promoting properties in mice were investigated. The complete circular genome of Bacillus velezensis TS5 contained 3,929,788 nucleotides with a GC content of 46.50%. The strain encoded 3,873 genes that partially related to stress resistance, adhesion, and antioxidants, as well as the production of secondary metabolites, digestive enzymes, and other beneficial nutrients. The genes of this bacterium were mainly involved in carbohydrate metabolism, amino acid metabolism, vitamin and cofactor metabolism, biological process, and molecular function, as revealed by KEGG and GO databases. To further investigate the potential of Bacillus velezensis TS5 as a probiotic strain, in vivo experiments were conducted using 40 five-week-old male specific pathogen-free C57BL/6J mice. The mice were randomly divided into four groups:high fiber diet control group (H group), high fiber diet probiotics group (HT group), low fiber diet control group (L group), and low fiber diet probiotics group (LT group). The H and HT groups were fed high-fiber diet (30%), while the L and LT groups were fed low-fiber diet (5%).The total bacteria amount in the vegetative forms of Bacillus velezensis TS5 per mouse in the HT and LT groups was 1×109 CFU per day, mice in the H and L groups were given the same volume of sterile physiological saline daily by gavage, and the experiment period lasted for 8 weeks. The results showed that Bacillus velezensis TS5 could improve intestinal digestive enzyme activity, liver antioxidant capacity, small intestine morphology, and cecum microbiota structure in mice. These findings confirmed the probiotic effects of Bacillus velezensis TS5 isolated from Tibetan sheep feces and provided the theoretical basis for the clinical application and development of new feed additives.