Bacteriocins are extra-cellular released peptides or protein with a bactericidal or bacteriostatic mode of
action against many Gram positive and Gram negative bacteria. Bacteriocins produced by lactic acid
bacteria (LAB) have received particular attention in recent years due to their potential application in the
food industry as natural preservatives. In this study, bacteriocin was extracted from Lactobacillus
acidophilus to determine its inhibitory effect against Bacillus subtilis, Staph.aureus (Gram-positive
bacteria) and E.coli (Gram-negative bacterium). The largest inhibition zone was obtained against
Bacillus subtilis followed by Staph.aureus while the smallest inhibition zone was obtained against
E.coli. The results revealed that the activity of bactericin extract was gradually decreased during storage
at 370C until 60 days and it was completely lost up to 90 days of storage. It was stable at 40C until 30
days then its activity was gradually decreased till 90 days of storage. While, the storage of extracted
bacteriocin at -200C persisted its activity for 90 days. The current study concluded that freezing
temperature was the most appropriate technique for preservation of bacteriocin.