Comparative Genomic Analysis Determines the Functional Genes Related to Bile Salt Resistance in Lactobacillus salivarius

Abstract

Lactobacillus salivarius has drawn attention because of its promising probiotic functions. Tolerance to the gastrointestinal tract condition is crucial for orally administrated probiotics to exert their functions. However, previous studies of L. salivarius have only focused on the bile salt resistance of particular strains, without uncovering the common molecular mechanisms of this species. Therefore, in this study, we expanded our research to 90 L. salivarius strains to explore their common functional genes for bile salt resistance. First, the survival rates of the 90 L. salivarius strains in 0.3% bile salt solutions were determined. Comparative genomics analysis was then performed to screen for the potential functional genes related to bile salt tolerance. Next, real-time polymerase chain reaction and gene knockout experiments were conducted to further verify the tolerance-related functional genes. The results indicated that the strain-dependent bile salt tolerance of L. salivarius was mainly associated with four peptidoglycan synthesis-related genes, seven phosphotransferase system-related genes, and one chaperone-encoding gene involved in the stress response. Among them, the GATase1-encoding gene showed the most significant association with bile salt tolerance. In addition, four genes related to DNA damage repair and substance transport were redundant in the strains with high bile salt tolerance. Besides, cluster analysis showed that bile salt hydrolases did not contribute to the bile salt tolerance of L. salivarius. In this study, we determined the global regulatory genes, including LSL_1568, LSL_1716 and LSL_1709, for bile salt tolerance in L. salivarius and provided a potential method for the rapid screening of bile salt-tolerant L. salivarius strains, based on PCR amplification of functional genes.

Genomic and metabonomic methods reveal the probiotic functions of swine-derived Ligilactobacillus salivarius

“…We have previously reported that L. salivarius improved the growth and health of weanling piglets [ 7 ]. Genomic evaluation was first used to obtain the genetic information of L. salivarius [ 18 , 31 ]. The phylogenetic tree suggested that L. salivarius was closely related to Ligilactobacillus salivarius MT57355.1 and MT585431.1, probiotic bacteria isolated from animals.…”

Ligilactobacillus salivarius CNCM I-4866, a potential probiotic candidate, shows anti-inflammatory properties in vitro and in vivo

“…The ability to tolerate bile salts is commonly known due to bile salt hydrolase activities ( Noriega et al, 2006 ). However, Pan et al (2021) have described the fact that, for some L. salivarius strains, other mechanisms could be responsible for this property. The growth of our strain was impacted by the low pH (pH 4 and pH 2) that mimic the passage in the gastrointestinal tract and, more specifically, gastric conditions.…”

Understanding Ligilactobacillus salivarius from Probiotic Properties to Omics Technology: A Review

“…However, Fang et al demonstrated that BSH is not the primary determinant of bile resistance in L. salivarius strains, and may have additional biological importance because of its varying effects upon bile as a signaling molecule in the host [ 48 ]. Pan et al also showed that there was no association between bile salt hydrolase and bile salt tolerance in L. salivarius strains and indicated that bile salt tolerance in L. salivarius strains was associated with processes such as peptidoglycan synthesis, the phosphotransferase system (PTS) and DNA damage repair [ 49 ]. This is consistent with the results of Wang et al [ 50 ] and Lv et al [ 51 ].…”