Identification, purification, characterization and biopreservation potential of antimicrobial peptide of Pediococcus acidilactici NCDC 252

Lactic acid bacteria (LAB) are economically important because of their fermentative aptitude and also confer health and nutritional benefits. Pediococcus acidilactici NCDC 252 is potential probiotic with novel genome that exhibited all in-vitro probiotic attributes, colonization in intestine and survival in conditions that mimick gastric, intestinal and vaginal fluid. Genome was screened for its ability to produce antimicrobial peptide (AMP). AMP activity was screened by spot on lawn method and by measuring zone of inhibition (ZOI) against indicator strain ( E.coli ). AMP production was optimized with highest production in MRS broth at 32℃, pH 6 and after 36 h of incubation under both aerobic and anaerobic conditions. AMP was purified 2.2 fold with yield of 7.2% and specific activity of 64.5 U mg/ml by ammonium sulphate precipitation (upto 70%) and gel filtration chromatography. Molecular weight of purified AMP was calculated to be 2.5 KDa. Tricine SDS-PAGE and LC/MS studies confirmed it to be a low molecular weight peptide. AMP was stable over pH range of 3 to 9 and temperature range of 40℃ to 100℃. Enzymatic treatment inactivated the AMP whereas, detergent treatment enhanced AMP’s activity. Biopreservation potential of purified AMP and whole NCDC 252 cells was studied by incubating them with some dairy products, apple juice, apricot pulp and pre-pasteurized wine over 72 h. Bacterial growth in AMP treated food products reduced significantly after 72 h. Viable cell count decreased to approximately half in all studied food items in both purified AMP treated and NCDC 252 treated food products.