Comparative study of two bacteriocins produced by representative indigenous soil bacteria.

The aim of this research work was to identify and characterized the bacteriocins produced by soil-associated bacteria. Bacillocin from Bacillus brevis Bb and pyocin from Pseudomonas aeruginosa Pa were found bioactive only against gram-positive bacteria tested. Maximum production of both the bacteriocins was observed at 32 degrees C in BHI medium. Production of both the bacteriocins started in the early exponential growth phase while the maximum production was observed during the stationary phase. Bacillocin Bb remained stable during 1-9 pH while pyocin Pa remained stable at pH 1-11. Both of the bacterocins were found resistant to high temperature (100 degrees C for 30 min), detergents (1% solutions of EDTA, Tween 20, Tween 80 and SDS) and organic solvents (1% solutions of Ethanol, Butanol, Methanol, Propanol, Chloroform, and Acetone). Activity of both was completely lost after proteinase K treatment suggesting their protein nature. Titre of bacillocin Bb was estimated to be 5280 AU/mL while the titre for pyocin Pa was calculated as 640 AU/mL. Both of the bacteriocins showed bacteriolytic mode of action against the indicator Bacillus strain BC31 and were found <10 KDa in their molecular mass.