Bile-Inducible Efflux Transporter from Bifidobacterium longum NCC2705, Conferring Bile Resistance

Abstract

Bifidobacteria are normal inhabitants of the human gut. Some strains of this genus are considered health promoting or probiotic, being included in numerous food products. In order to exert their health benefits, these bacteria must overcome biological barriers, including bile salts, to colonize and survive in specific parts of the intestinal tract. The role of multidrug resistance (MDR) transporters in bile resistance of probiotic bacteria and the effect of bile on probiotic gene expression are not fully understood. In the present study, the effect of subinhibitory concentrations of bile on the expression levels of predicted MDR genes from three different bifidobacterial strains, belonging to Bifidobacterium longum subsp. longum, Bifidobacterium breve, and Bifidobacterium animalis subsp. lactis, was tested. In this way, two putative MDR genes whose expression was induced by bile, BL0920 from B. longum and its homolog, Bbr0838, from B. breve, were identified. The expression of the BL0920 gene in Escherichia coli was shown to confer resistance to bile, likely to be mediated by active efflux from the cells. To the best of our knowledge, this represents the first identified bifidobacterial bile efflux pump whose expression is induced by bile.

Gut and Root Microbiota Commonalities

“…Gut bacteria are exposed to bile salts that solubilize diet fat, have antimicrobial activities (127), and regulate bacterial gene expression. An efflux transporter of the multidrug resistance type (MDR) was induced in Bifidobacterium by bile (128). Different bile substances have been identified to control gene expression in bifidobacteria (129).…”

Catabolism of Glucose and Lactose in Bifidobacterium animalis subsp. lactis, Studied by 13 C Nuclear Magnetic Resonance

“…The qRT-PCR experiments were performed as described by Gueimonde et al (31). Samples from two biological replicates were analyzed in at least two independent PCR runs.…”

Bile salt hydrolase and antimicrobial activities of three bile resistant probiotics Lactobacillus plantarum strains isolated from Cameroonian artisanal fermented milk

“…Amongst those mechanisms are the bile efflux (17,18,19), counteracting H + accumulation by ATPase F0F1 pump (20), modification of plasma membrane composition (21)(22)(23) and bile salts deconjugation through the activity of bile-salt-hydrolases (BSHs) (24)(25)(26). The bile salts hydrolases produced by lactic acid bacteria are responsible for the deconjugation of bile salts with the formation of amino acid residues and deconjugated bile acids.…”