ISOLATION, PURIFICATION AND CHARACTERIZATION OF A BACTERIOCIN WITH BROAD SPECTRUM ACTIVITY FROM Lactococcus lactis JC10 FROM PERISHABLE PAPAYA FRUIT

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.