Genome-Wide Identification of Small RNAs in Bifidobacterium animalis subsp. lactis KLDS 2.0603 and Their Regulation Role in the Adaption to Gastrointestinal Environment

OBJECTIVE Bifidobacteria are one of the predominant bacterial species in the human gastrointestinal tract (GIT) and play a vital role in the host's health by acting as probiotics. However, how they regulate themselves to adapt to GIT of their host remains unknown. METHODS Eighteen bifidobacterial strains were used to analyze their adaptive capacities towards simulated GIT environment. The strain with highest survival rate and adhesion ability was selected for comparative genome as well as transcriptomic analysis. RESULTS The Bifidobacterium animalis subsp. lactis KLDS 2.0603 strain was demonstrated to have the highest survival rate and adhesion ability in simulated GIT treatments. The comparative genome analysis revealed that the KLDS 2.0603 has most similar whole genome sequence compared with BB-12 strain. Eleven intergenic sRNAs were identified after genomes prediction and transcriptomic analysis of KLDS 2.0603. Transcriptomic analysis also showed that genes (mainly sRNAs targeted genes) and sRNAs were differentially expressed in different stress conditions, suggesting that sRNAs might play a crucial role in regulating genes involved in the stress resistance of this strain towards environmental changes. CONCLUSIONS This study first provided deep and comprehensive insights into the regulation of KLDS 2.0603 strain at transcription and post-transcription level towards environmental.