Effect of pH, heat treatments and proteinase K enzyme on the activity of Lactobacillus Acidophilus bacteriocin

Abstract

Bacteriocins are natural metabolites produced by many strains of Lactic acid bacteria that used in food preservation. They have potential healthy role in suppressing the growth of some spoilage and pathogenic bacteria. The aim of the current study was to demonstrate the stability of the bacteriocin extracted from Lactobacillus acidophilus at different pH values, heat treatments and proteinase K enzyme. The obtained results revealed that the inhibitory effectiveness of bacteriocins was higher on Gram-positive bacteria than Gram-negative bacteria. Further, the largest inhibition zone was obtained by L. acidophilus bacteriocin against Bacillus subtilis while the smallest one was against E.coli. The extracted bacteriocin exhibited broad spectrum of inhibition at concentration 6400AU/ml against Staph. aureus, Bacillus subtilis and E.coli. The antimicrobial activity of crude supernatant fluid was stable after heating at 100°C for 30 min and declined thereafter. Stability of antimicrobial activity was observed at pH ranged from 2.0 to 8.0. Its active principle was proteinaceous in nature since the bacteriocin was inactivated by proteinase K enzyme.