Abstract
Food-grade bacteria capable of producing bacteriocin with preservation abilities have been isolated from perishable papaya. Characterization of the bacteria isolated on MRS agar, by using 16S rRNA sequence analysis, exhibited antagonistic effect towards the growth of a wide range of Gram + and Gram - bacteria including pathogens also. Extracellularly produced bacteriocin was purified by ion-exchange chromatography on a Fast Protein Liquid Chromatography (FPLC) system equipped with a Mono-Q column. The purity rate and molecular mass of 21 kDa of this compound were determined using SDS-PAGE. Activity units (AU) of bacteriocin were increased in each step of purification, reaching up to 9500 AU/mL. The increase in the activity units directly affected the antimicrobial activity of purified bacteriocin, resulting in an increase of the inhibition zones against indicator bacteria. It withstood very high temperature, up to 115.6 °C, for 10 min but lost activity after autoclaving (121°C), wider pH range, from 3.0 to 10.0, complete inactivation in the presence of proteolytic enzymes (protease and α chymotrypsin) and storage stability up to 6 months.
Highlights
The ability of Lactic Acid Bacteria (LAB) to inhibit the growth of other bacteria has been known for many years
Produced bacteriocin was purified by ion-exchange chromatography on a Fast Protein Liquid Chromatography (FPLC) system equipped with a Mono-Q column
LAB have been defined as "generally recognized as safe" (GRAS) microorganisms .The inhibitory activity of LAB may be attributed to their acidification of the medium, competition for substrates and the production of antimicrobial compounds such as Hydrogen peroxide, Diacetyl and antimicrobial peptides known as Bacteriocins ( Parente et al, 1999)
Summary
The ability of Lactic Acid Bacteria (LAB) to inhibit the growth of other bacteria has been known for many years. Schnell et al 1988 stated that many of the Lactococcal bacteriocins described are very different from Nisin and does not belong to the lantibiotic family of bacteriocins The objective of this present study was to describe a novel bacteriocin produced by Lactococcus lactis JC10 isolated in our laboratory from papaya fruit. This bacteriocin having potential antibacterial activity including pathogens, thermal stability and small production time can be used in food industry as an alternative for chemical preservatives. Purification and characterization of this bacteriocin was studied in detail for their potential application as food preservative in future
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