Assessment of the probiotic, anti-bacterial, and anti-biofilm characteristics of Lacticaseibacillus rhamnosus CWKu-12, along with its potential impact on the expression of virulence genes in Listeria monocytogenes ATCC 19115

Abstract

The purpose of this study was to investigate the potential probiotic properties, gene expression related to biofilm formation, and anti-biofilm capabilities of Lacticaseibacillus rhamnosus CWKu-12. This strain showed notable resistance to acidic conditions, gastrointestinal environments, and bile salts. Additionally, L. rhamnosus displayed significant levels of auto-aggregation (36.60%), hydrophobicity (52.60%), co-aggregation (29.10%), free radical scavenging activities (55–59%), and cholesterol reduction (49.30%). Its ability to compete with, replace, and hinder the adhesion of Listeria monocytogenes was measured at 41.70%, 22.60%, and 30.54% respectively. L. rhamnosus also showed an adhesion rate of 11.80% to epithelial cells, did not exhibit DNase or hemolytic activity. It was susceptible to the antibiotics ciprofloxacin, erythromycin, and chloramphenicol and semi-susceptible to ampicillin, imipenem, nitrofurantoin, and nalidixic acid. The strain's cell free supernatant (CFS) effectively inhibited and eliminated L. monocytogenes biofilm formation, with inhibitory rates of 44.30% and eradication rate of 38.70%. Treatment with CFS also led to a significant decrease in the expression of various genes related to L. monocytogenes by percentages ranging from 35.54% to 79.80%. Overall, these findings support the potential of L. rhamnosus CWKu-12 as a probiotic, with its ability to survive in the digestive system, and combat harmful bacteria making it a promising candidate.