Isolation and partial characterization of antifungal metabolites produced by bacillus sp. IBA 33

Abstract

Antifungal proteins produced by Bacillus sp.IBA 33 were purified by ammonium sulfate precipitationand DEAE-Sephacel column chromatography. The twopurified proteins inhibited the growth of Geotrichum can-didum, the sour rot disease agent in lemon. The proteinswere stable at 20 (3 months), 40, 60 and 100C (30 min)and remained active after sterilization at 121C for 15 min.Their hydrophobic nature was proved and when weredeveloped with ninhydrin they did not show any free aminogroups. The infrared spectrum showed vibrational modescorresponding to peptide, ester or ketone links and satu-rated CH links corresponding to long chain fatty acids. UVscan spectroscopy showed tyrosine and or tryptophanamino acids in their composition. The remarkable thermo-resistance of proteins may be a good feature to be used inthe development of a new biocontrol method of Geotri-chum candidum.