Prevalence of bacteriocin genes in Lactobacillus strains isolated from fecal samples of healthy individuals and their inhibitory effect against foodborne pathogens.

ABSTRACT

OBJECTIVES: Foodborne diseases are considered as an important public health issue. The purpose of the current study was to isolate Lactobacillus spp. strains from fecal samples, investigate their antimicrobial properties, and assess the expression of genes encoding bacteriocin in co-culture of Lactobacillus with enteric pathogens. MATERIALS AND METHODS: Fecal samples of healthy people were collected. Human colon adenocarcinoma cell line Caco-2 was used to examine Lactobacillus strains adherence capacity. Quantitative real-time reverse transcription PCR (qRT-PCR) was used to determine bacteriocin-encoding genes expression in co-culture of the selected Lactobacillus strain with Salmonella, Shigella, and two diarrheagenic Escherichia coli serotypes during 4, 6, and 24 hr of incubation. RESULTS: The selected L. plantarum strain was able to inhibit four foodborne pathogens in both methods. L. plantarum No.14 exhibited the highest ability to adhere to Caco-2 cells. In this study, pln F, sak P, pln I, pln B, and pln J genes of L. plantarum No.14 were upregulated in co-culture of L. plantarum No.14 with diarrheagenic E. coli serotypes. In addition, acd, Lactacin F, sak P, pln J, pln EF, and pln NC8 genes as well as pln NC8 and pln A genes mRNA levels were significantly increased in co-culture of L. plantarum No.14 with Shigella dysenteriae, and Salmonella typhi, respectively, during 24 hrs of incubation. CONCLUSION: Other studied genes were down-regulated during the incubation time. The selected L. plantarum strains could be served as alternative antimicrobial agents against pathogens which could contaminate foodstuffs and are responsible for human diseases.