A novel antibacterial compound produced by Lactobacillus plantarum LJR13 isolated from rumen liquor of goat effectively controls multi-drug resistant human pathogens.

ABSTRACT

Probiotic lactobacilli have been implicated in the production of many low molecular weight bioactive molecules with tremendous potential to kill multidrug resistant human pathogens. The aim of the present study is to purify, characterise and evaluate a novel compound produced by a probiotic Lactobacillus plantarum LJR13 strain. The compound was purified employing silica gel column chromatography followed by RP-HPLC technique. The compound was identified as tert-butyl-4-(4-oxo-(2-((2-oxo-1- (p-tolyl) -2- (p-tolyloxy) ethyl) carbamoyl) pyrrolidin-1-yl) butanoyl) piperazine-carboxylate (BPBP) through various spectral techniques. Exhaustive literature search has revealed that the compound BPBP has not been reported from Lactobacillus species so far and ours is the first report describing its spectrum of activities against multidrug resistant human pathogens together with the morphological and physiological manifestations it brings about in the normal as well as human colon carcinoma cells. The MIC of BPBP for Listeria monocytogenes and Staphylococcus aureus was 15.62 µg/mL and 62.50 µg/mL respectively; however, for Acinetobacter baumannii the MIC was determined to be 31.25 µg/mL. Scanning electron microscopic studies of BPBP treated L. monocytogenes, S. aureus, and A. baumannii revealed the presence of blebs on the cell wall which represents the compromise in the cell wall integrity. While BPBP showed no significant cytotoxicity on mouse embryonic fibroblast cells, (NIH-3T3), marked discernible cytotoxic effect was observed on colorectal carcinoma cells, HCT-116, suggesting potential anti-cancer activity. Molecular docking studies displayed the interaction of BPBP with appropriate drug resistance associated proteins such as Penicillin binding proteins in gram positive L. monocytogenes and S. aureus and beta-lactamase in gram negative A. baumannii.