ABSTRACT

A major characteristic shared among Bacillus strains is the ability to produce a wide range of antimicrobial compounds that are active against bacteria and fungi. Bacillus species was isolated from soil samples collected from refuse dump site. The bacterial isolate exhibited antagonistic activity when cultured with fungi on Potato Dextrose agar plates. Antifungal metabolites produced by Bacillus species in Potato Dextrose Broth were extracted from fluid culture supernatant by evaporation with ethyl acetate giving a yield of 0.21g dry metabolites from 1 litre fluid culture on average. The antifungal metabolites inhibited mycelial growth of fungal species – Aspergillus, Rhizopus and Fusarium. The inhibition zones were observed for more than four days and there was no observed change in the size of the zones. The antifungal metabolites were subjected to different pH levels and were active and stable over a wide range of pH (2-10). They were exposed to very high temperatures and were stable and remained active after sterilization at 121oC for 15min. The metabolites were soluble in water and organic solvents like ethanol and were resistant to denaturation by enzymes. The effect of these antifungal metabolites against postharvest fungal pathogens under various circumstances suggest that they could be a potent source of antifungal not just for postharvest fungal pathogens but human and animal fungal pathogens alike.