LAUSR

BACKGROUND Toxin-antitoxin (TA) systems are prevalent adaptive genetic elements in bacterial genomes, which can respond to environmental stress. While, few studies have addressed TA systems in probiotics and their roles in the adaptation to gastrointestinal transit (GIT) environments. RESULTS The Weissella cibaria 018 could survive in pH 3.0 - 5.0 and 0.5 - 3.0 g L-1 bile salt, and its HigBA system responded to the bile salt stress, but not to acid stress. The toxin protein HigB and its cognate antitoxin protein HigA had 85.1% and 100% similarity with those of Lactobacillus plantarum, respectively, and they formed the stable tetramer HigB-(HigA)2 -HigB structure in W. cibaria 018. When exposed to 1.5 - 3.0 g L-1 bile salt, the transcriptions of higB and higA were upregulated with 4.39 - 19.29 and 5.94 - 30.91 folds, respectively. Meanwhile, W. cibaria 018 gathered into a mass with 48.07% survival rate and its persister cells were found to increase 8.21% under 3.0 g L-1 bile salt. CONCLUSION The HigBA TA system of Weissella cibaria 018 responded to the bile salt stress, but not to acid stress, which might offer novel perspectives to understand the tolerant mechanism of probiotics to GIT environment. This article is protected by copyright. All rights reserved.