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 center dot 935 mg ml(-1), MBC = 0 center dot 935 mg ml(-1)), Yersinia enterocolitica (MIC = 12 center dot 5 mg ml(-1), MBC = 50 mg ml(-1)) and Bacillus cereus (MIC = 6 center dot 25 mg ml(-1), MBC = 12 center dot 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 center dot 4%-5 center dot 2%) against red blood cells. Lacticaseibacillus paracasei AS20(1) showed probiotic properties, including high acid resistance, hydrophobicity (47 center dot 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.

Automated summary

This study aimed to find lactic acid bacteria that can produce antibacterial exopolysaccharide (EPS) against foodborne pathogens. The EPS produced by the AS20(1) strain showed inhibitory effects on the growth of Listeria monocytogenes, Yersinia enterocolitica, and Bacillus cereus. The AS20(1) strain was identified as Lacticaseibacillus paracasei and showed probiotic properties. The antibacterial EPS had various functional groups, an amorphous structure, and a smooth surface, making it suitable for food packaging.