Lactic Acid Bacteria from Fresh Fruits and Vegetables as Biocontrol Agent of Foodborne Bacterial Pathogens

Abstract

The presence of lactic acid bacteria (LAB) in dairy products has long been established but the
occurrence of the particular group of bacteria in fruits has rarely been focused. Therefore, different
lactic acid bacteria generally found in fruits, cultivated in Pakistan were studied. Following the culture
enrichment method randomly selected fruit samples were analyzed. About 12 different isolates of
Lactobacillus spp. were obtained from 25 different fruits and vegetables. The identification was based
on conventional morphological and biochemical analysis. Prior to all these manipulations the growth
conditions were carefully optimized for the respective strains. This study evaluated the efficacy of
lactic acid bacteria (LAB) isolated from fresh fruits and vegetables as biocontrol agents against the
foodborne human bacterial pathogens (Escherichia coli, Enterococcus faecalis, Proteus sp. and
Pseudomonas aeruginosa). The antagonistic activity of LAB strains were tested in vitro and all tested
microorganisms except few were inhibited by at least one isolate. Cell-free supernatants of selected
antagonistic bacteria were studied to determine the nature of the antimicrobial compounds produced.