bacteriocin

The inhibitory activity of bacteriocins produced by Lactic acid bacteria isolated from raw cattle and goat milk and other processed milk products against Mycobacterium bovis and Mycobacterium tuberculosis in milk was studied using spectrophotometry. Six bacteriocin positive strains of LAB were isolated and identified as Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus fermentum, Lactobacillus brevis, Lactococcus lactis and Streptococcus thermophilus. The antimycobacterial activity of the bacteriocins in milk showed that the bacteriocins from Lactobacillus inhibited the growth of the mycobacterium over a period of 15 days while bacteriocin from Streptococcus did not inhibit the Mycobacteria in milk.  However, the activity of the bacteriocin were lost after the 15th day as shown by increase in absorbance on day 18. The bacteriocin mix from all six bacteriocins against Mycobacteria was the most efficient when compared to that of individual bacteriocins, recording a significant decline in absorbance at from 0.79 to 0.026 even on day 18.

In present study, Brevicin produced from Brevibacillus borstelensis AG1 isolated from Marcha - a natural herbal cake of North East India was used to enhance the shelf life and microbial safety of orange juice. Food borne pathogens viz. Listeria monocytogenes MTCC 839, Bacillus subtilis CRI and Clostridium perfringens MTCC 1739were inoculated at the amount of 8.16, 8.13 and 8.18 log CFU/ml, respectively in orange juice to study the preservative effect of bacteriocin against them as compared to chemical preservative – sodium benzoate and commercial biopreservative i.e. nisin. Viable cells were counted periodically and a consistent reduction in number of viable cells of each tested pathogen was observed. Brevicin when tested was found antagonistic to most challengeable and serious food borne pathogens to control in processed fruit/vegetables products. Brevicin was found active over a wide pH range i.e. 3.0 to 11.0 and thermostable upto 100oC. It showed better preservative potential by reducing the pathogenic load of indicators in orange juiceas compared to control having maximum spoilage proving its potential as a natural preservative to enhance microbial safety and shelf life of different food items.