AUTHOR=Xin Wei-Gang , Li Xin-Dong , Lin Yi-Cen , Jiang Yu-Hang , Xu Mei-Yu , Zhang Qi-Lin , Wang Feng , Lin Lian-Bing 

TITLE=Whole genome analysis of host-associated lactobacillus salivarius and the effects on hepatic antioxidant enzymes and gut microorganisms of Sinocyclocheilus grahami

JOURNAL=Frontiers in Microbiology

VOLUME=Volume 13 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.1014970

DOI=10.3389/fmicb.2022.1014970

ISSN=1664-302X

ABSTRACT=As a fish unique to Yunnan Province in China, Sinocyclocheilus grahami hosts abundant probiotic resources in its intestinal tract. However, the genomic characteristics of the probiotic bacteria in its intestine and their effects on the host have not yet been established. In this study, functional genomics and host response of a strain, Lactobacillus salivarius S01, isolated from the intestine of S. grahami were investigated. The results revealed that the total length of the genome was 1737623 bp (GC content, 33.09%), comprised of 1895 genes, including 22 rRNA operons and 78 transfer RNA genes. Three clusters of bacteriocin-related genes were identified using antiSMASH and BAGEL4 database predictions. In addition, manual examination confirmed the presence of functional genes related to stress resistance, adhesion, immunity, and other genes responsible for probiotic potential in the genome of L. salivarius S01. Subsequently, the probiotic effect of strain S01 was investigated in vivo by feeding S. grahami a diet with bacterial supplementation. The results showed that probiotic supplementation increased the activity of antioxidant enzymes in the hepar and reduced oxidative damage. Furthermore, the gut microbial community and diversity of S. grahami from different treatments were compared using high-throughput sequencing. At the phylum level, the abundance of Proteobacteria decreased with probiotic supplementation, while the abundance of Firmicutes, Actinobacteriota, and Bacteroidota increased. At the genus level, there was a significant decrease in the abundance of the pathogenic bacterium Aeromonas and an increase in the abundance of the probiotic bacterium Bifidobacterium. The diversity index of the gut microbial community in the group supplemented with probiotics was higher than that in the control group, indicating that supplementation with probiotic increased gut microbial diversity. The results of this study suggest that L. salivarius S01 is a promising probiotic candidate that provides multiple benefits for the microbiome of S. grahami.