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

Bacteriocins are natural metabolites produced by many strains of Lactic acid bacteria that used in foodpreservation. They have potential healthy role in suppressing the growth of some spoilage andpathogenic bacteria. The aim of the current study was to demonstrate the stability of the bacteriocinextracted from Lactobacillus acidophilus at different pH values, heat treatments and proteinase Kenzyme. The obtained results revealed that the inhibitory effectiveness of bacteriocins was higher onGram-positive bacteria than Gram-negative bacteria. Further, the largest inhibition zone was obtainedby L. acidophilus bacteriocin against Bacillus subtilis while the smallest one was against E.coli. Theextracted 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 stableafter heating at 100°C for 30 min and declined thereafter. Stability of antimicrobial activity was observedat pH ranged from 2.0 to 8.0. Its active principle was proteinaceous in nature since the bacteriocin wasinactivated by proteinase K enzyme