Bacteriocin:Production and optimization by Lactobacillus species

The isolated species of Lactobacilli shows pronounced antibacterial activity between early logarithmic and early stationary phase. The maximum activity in composed medium was achieved at initial pH of 6, Incubation temperature 37°C, and incubation period of 24h under static condition. Supplementation or replacement of nutrients demonstrated that larger quantities of bacteriocin could be produced by addition of Glucose (2%), using the alternative sugars like Lactose and maltose (2%), and NaCl (2-4%), while the addition of glycerol had no profound effect on production. Salting out and dialysis methods are efficient for the partial purification of bacteriocin since it showed the increase in the activity from 400AU/mL to 1200AU/mL. The compound produced by Lactobacilli was fully inactivated by some of the proteolytic enzymes, which confirms their proteinaceous nature. The antibacterial activity of cell-free culture was not affected by treatment with the α-amylase suggesting that the activity of the bacteriocin producing organism is not dependent on the glycosylation. The antibacterial compound shows wide range of thermo stability from 70°C-121°C for 15min. The well diffusion assay showed that the bacteriocin produced by the given Lactobacilli is inhibiting the growth of Staphylococcus aureus, Bacillus subtilis, Serratiamarsecens, Escherichia coli, Pseudomonas aeroginosaand Proteus vulgaris showing a broad spectrum of inhibition. The molecular weight of the peptide is 6 kDa by SDS-PAGE analysis. The antimicrobial activity of the proteinaceous compounds such as bacteriocins or bacteriocin-like inhibitory compounds produced by Lactobacilli isolated in this work are largely known and have been found to have potent antimicrobial activities towards closely related bacteria and undesirable harmful microorganisms. They are helpful in the field of food preservation or safety, health care, and pharmaceutical application. Key words: Bacteriocin, Food preservation, Antimicrobial