Isolation and characterization of exopolysaccharide derived from Lacticaseibacillus paracasei AS20(1) with probiotic potential and evaluation of its antibacterial activity.

This study was done to find exopolysaccharide (EPS)-producing lactic acid bacteria (LAB) against foodborne pathogens. Isolated LAB were screened to find the ones with the ability to produce antibacterial EPS against foodborne pathogens. Among tested EPSs, EPS of AS20(1) isolate showed inhibitory effects on the growth of Listeria monocytogenes (MIC = 0·935 mg ml -1 , MBC = 0·935 mg ml -1 ), Yersinia enterocolitica (MIC = 12·5 mg ml -1 , MBC = 50 mg ml -1 ) and Bacillus cereus (MIC = 6·25 mg ml -1 , MBC = 12·5 mg ml -1 ). According to 16S rRNA sequencing, AS20(1) showed the closest similarity to Lacticaseibacillus paracasei (100%). This antibacterial EPS showed negligible toxicity (4·4%-5·2%) against red blood cells. Lacticaseibacillus paracasei AS20(1) showed probiotic properties, including high acid resistance, hydrophobicity (47·5%), autoaggregation and coaggregation with foodborne pathogens. Also, L. paracasei AS20(1) showed no haemolysis activity and antibiotic resistance. Characterization of antibacterial EPS revealed that it is a heteropolysaccharide with various functional groups, amorphous structure, and smooth surface, sheet and compact structure, which can be suitable for food packaging. L. paracasei AS20(1) and its antimicrobial EPS can be used to make functional food.