Isolation and identification of Lacticaseibacillus rhamnosus YT and the antibacterial characteristics of its cell free supernatant and cells

Abstract

Abstract Lactic acid bacteria (LAB) which produce diverse imperative antimicrobial metabolites have an immense number of applications in food industry. Here, human-derived strain YT was isolated due to its cell free supernatant (CFS-YT) and cells (Cs-YT) respectively performed obvious inhibitory ring to Gram positive and negative spoilage bacteria. Strain YT was identified as Lacticaseibacillus rhamnosus YT by 16s rDNA sequence and morphology. The antibacterial activity of CFS-YT was demonstrated to be growth-dependent, pH sensitive, broad thermostable and proteases insensitive. Cs-YT displayed a broad antibacterial spectrum with the action mode of bacteriostatic. The antibacterial activity of Cs-YT was due to substances located at the cell surface which was sensitive to heat, stable at broad pH gradients and sensitive to specific proteases. These data suggested that L. rhamnosus YT could be used as alternative antimicrobial agents against foodborne spoilage bacteria in food industry.