Evaluation of survial growth, antimicrobial activity, antibiotic susceptibility, cytotoxicity and genetransfer ability of lactobacillus acidophilus in three commercial probiotics in Vietnam

Abstract

There has been a growing interest in the use of probiotic products in Vietnam due to their therapeutic effects without sufficient validation of microbial characteristics, raising serious questions about safety and efficacy issues. Therefore, this study aimed to investigated the quality of three commercial probiotics in Vietnam pharmaceutical market by evaluating the viability, antimicrobial activity, antibiotic susceptibility, cytotoxicity and plasmid transfer ability of compositional Lactobacillus strains to increase the awareness in probiotic uses as well as study their potential applications. The results showed the actual probiotic contents of A-Bio, B-Bio and C-Bio products, which are Lactobacillus helveticus in A-Bio and Lactobacillus acidophilus in B-Bio and C-Bio. These Lactobacillus strains retained relatively good viability but is not in agreement with the lables. All tested Lactobacillus spp. displayed intermediate to high resistance against Salmonella typhi, Escherichia coli, Vibrio parahaemolyticus, Staphylococcus aureus, Pseudomonas aeruginosa, Serratia marcescens and Micrococcus luteus. The antibiotic susceptibility test indicated that Lactobacillus strains were highly resistant to tetracyline and beta-lactam antibiotics including ampicillin, cephalexin and cefaclor; whereas high concentration of vancomycin could inhibit the growth of the three strains. No cytotoxic effect of these probiotic strains was recorded on leukemia, liver and breast cancer cell lines. Conjugation was observed when co-culturing B-Bio L. acidophilus with S. typhi and E. coli. In addition, tet(Q) gene and blaTEM gene were detected in plasmids of Lactobacillus strains but no gene transfer could be recorded. The study found out the incorrect strain and low viable in probiotic that should be overcome in probiotic development. Moreover, this study will bring out the way to improve the production of biological compounds in future. Keywords: Lactobacillus acidophilus, Lactobacillus helveticus, viability assessment, antimicrobial activity, antibiotic susceptibility, cytotoxicity, plasmid transfer ability, tet(Q) gene, blaTEM gene