Molecular Detection and Antimicrobial Activity of Enterolysin a Endopeptidase among Enterococcus faecalis Strains of Different Origins

Abstract

Aims: The target of present study is to determine the frequency of occurrence of enterolysin A gene in Enterococcus faecalis strains from different sources and surveys about antibacterial effect of enl A gene positive strains. Study Design: Enterolysin A is a class IV bacteriocin with broad spectrum of antimicrobial activity that is produced by some E. faecalis strains. However, research on the presence and antibacterial activity of this bacteriocin in different sources is very limited. Place and Duration of Study: Islamic Azad University of North Tehran Branch Laboratory, between May 2011 and February 2012. Methodology: In this study, the occurrence of enterolysin A structural gene in a target of 68 E. faecalis strains of three sources (animal feces, feed and surface water) was surveyed. Enterococcal strains were isolated from other feces Gram-positive and negative bacteria using Bile Aesculin Azide agar medium. After strains purification, E. faecalis bacteria were identified and the occurrence of enterolysin A gene was evaluated by using PCR method. The antimicrobial spectrum of enl A gene positive E. faecalis strains was assayed by deferred antagonism assay method on the some gram-positive and negative pathogen bacteria. Results: Based on our results, 20 strains (29.4%) possessed enterolysin A structural gene. Different frequencies of the enterolysin A gene occurrence were detected in strains according to thebacterial origins; the strains from silage and lovebirds showed the highest frequency of enterolysin A gene presence. These gene-positive strains inhibited the growth of indicator bacteria such as clinical strain of Pseudomonas aeruginosa, Listeria monocytogenes, Bacillus cereus and Salmonella enterica PTCC1709. Conclusion: Enterolysin A structural gene similar to the other enterocin genes present in enterococci of different origins. Moreover, efficiency of enterolysin A against pathogenic bacteria makes it a suitable candidate for their application in veterinary medicine, alternative antimicrobial compounds or bio-preservatives in food or feed.