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STUDIES ON BREVICIN AF01: A BACTERIOCIN LIKE INHIBITORY SUBSTANCE ACTIVE AGAINST METHICILLIN RESISTANT STAPHYLOCOCCUS AUREUS

FIRDOUS FAHEEM, SADIA SAEED AND SHEIKH AJAZ RASOOL^*

Abstract: Bacillus brevis AF01, isolated from wheat field, has been found to produce proteinaceous antibacterial substance Brevicin AF01. The inhibitory activity could not be related to bacteriophages. It has a narrow spectrum of activity against gram-positive bacterial strains only. Brevicin AF01 revealed bactericidal effect against Staphylococccus aureus FS10. It was also found to be active against several strains of methicillin resistant Staphylococcus aureus.  Its production was started in the early stationary phase and continued till late stationary phase. Maximum production of Brevicin AF01 was observed when the producer strain was grown in BHI broth without NaCl supplement, at neutral pH and at 37°C. It remained stable at 60°C and 80°C for 30 minutes. The activity decreased at 100°C and was completely lost by autoclaving (121°C, 15 lb/sq inch, for 15 minutes). It remained stable at wide pH range (3-11). Bioactivity of Brevicin AF01 was relatively less affected by treatment with organic solvents, heavy metal salts but lost completely by surfactants and proteolytic enzymes. The activity was also found sensitive to lipase and thus Brevicin AF01 appeared to be a lipoprotein.

Lab of Molecular Genetics, Department of Microbiology,  University of Karachi-75270, Pakistan.