ASSESSMENT OF ANTIBACTERIAL ACTIVITIES OF PEDIOCIN PRODUCED BY PEDIOCOCCUS ACIDILACTICI LAB 5

Abstract

Pediocin NV 5, produced by Pediococcus acidilactici LAB 5, was found to be active against a number of food spoilage and food‐related health hazards associated gram‐positive bacteria. The partially purified bacteriocin was tested for its mode of action against two sensitive strains – Enterococcus faecalis MB1 and Leuconostoc mesenteroides Ly and was found to be bactericidal at a concentration of 800 AU/mL. Atomic absorption spectroscopy for K+ ions showed that pediocin NV 5 caused pore formation which was comparable to valinomycin on human pathogenic Listeria monocytogenes Microbial Type Culture Collection (MTCC) 657. The scanning electron micrographs showed a great variation in cell morphology like elevated protrusion and barrel shape formation from cocci in treated cells. Pediocin NV 5 treatment (800 AU/mL) did not cause any loss of cellular proteins and DNA from treated cells but treatment at higher activity units (20,000 AU/mL) caused lysis in Listeria monocytogenes MTCC 657 proving its lytic mode of action. PRACTICAL APPLICATIONS Postpackage food spoilage of fermented food products of fish, meat, vegetables and dairy products causes a major problem in food preservation. The most predominating spoilage bacteria in both fresh and processed fish, meat, vegetables and dairy products are the species of Bacillus, Campylobacter, Clostridium, Enterobacter, Listeria, Pseudomonas, Salmonella, Serratia, Staphylococcus, Yersinia, etc.; some of them are also reported to have pathogenicity in humans. Among them, Listeria monocytogenes is responsible for listeriosis, a disease with high mortality rate in humans. The use of bacteriocin as food biopreservative is an alternative method for food preservation and a good substitute for the conventionally used chemical preservatives. Results of this study show that high thermotolerant bacteriocins like pediocin NV 5, produced by Pediococcus acidilactici LAB 5, which has bactericidal activity at very low concentration against these organisms, can effectively be considered as a good candidate for food preservation.

Production and partial characterisation of an inducer‐dependent novel antifungal compound(s) by Pediococcus acidilacticiLAB 5

“…Solid culture was found to support higher antifungal compound production than broth culture. MRS broth adjusted to pH 6.2 ± 0.3 produced more antifungal compound at an optimal temperature of 28 °C for 48 h. The absence of antifungal activity in the culture aliquot of other media such as TGE and TGE amended with Tween 80, which supported bacteriocin production maximally, also proved that the bacteriocin produced by the strain was not responsible for antifungal activity. Pre‐cultured fungal mycelia extract also had no influence on antifungal compound production.…”

“…Previously we reported on the detection and isolation of antifungal compound(s) produced by P. acidilactici LAB 5 . Although the strain P. acidilactici LAB 5 is bacteriocin‐positive and produces a high amount of bacteriocin (2400 activity units mL −1 ) with strong antibacterial activity, this antifungal activity is not due to the bacteriocin …”

“…24 Although the strain P. acidilactici LAB 5 is bacteriocin-positive and produces a high amount of bacteriocin (2400 activity units mL −1 ) with strong antibacterial activity, this antifungal activity is not due to the bacteriocin. 25 Several studies have focused on the characterisation of antifungal compounds produced by LAB species in single media such as de Man/Rogosa/Sharpe medium (MRS) or wheat flour hydrolysate, but none in induction systems. 14 -17 The focus of the present study was the inducer-dependent production of antifungal compound(s) by the P. acidilactici LAB 5 strain.…”

Effect of in vitro selected synbiotics (galactooligosaccharide and mannanoligosaccharide with or without Enterococcus faecalis) on growth performance, immune responses and intestinal microbiota of juvenile narrow clawed crayfish, Astacus leptodactylus lep

“…Anaerobic growth of E. faecalis was studied using the protocol described previously. To create an anaerobic condition, sodium thioglycolate (0.2%, w/v) was added to all media (Mandal, Sen, & Mandal, 2010) and test tubes were covered with seal layers of sterile paraffin (Elliott & Dole, 1947). After inoculating 10 8 CFU mL −1 of E. faecalis, the experimental cultures were incubated at 30°C for 24 hr.…”

Longterm storage of post-packaged bread by controlling spoilage pathogens using Lactobacillus fermentum C14 isolated from homemade curd

“…Mycelia were washed with sterilized 50 mM sodium phosphate buffer followed by re-suspension in 25 ml of the same buffer. Mycelia of each fungus were treated with the 5 ml of antifungal extract (500 μg/ml) up to 10 h and the supernatants were withdrawn at intervals of two hours, centrifuged and the presence of nucleic acids and proteins were determined by measuring the optical densities at 260 nm and 280 nm respectively [ 25 ].…”