Diversity, characterization and antimicrobial activities of Bacillus cereus strains isolated from soil

Abstract

In this study, 10 Bacillus cereus strains were isolated from different soil samples. Selective isolation of the strains was carried out on MYP agar medium. Biochemical identification was also confirmed by fatty acid methyl ester (FAME) analysis and ribotyping. Strains were analysed phenotypically by sensitivity to common antibiotics, diarrhoeal enterotoxin production by BCET-RPLA, SDS-PAGE analyses of whole cell proteins. Genotyping included automatized ribotyping by Eco RI enzyme. Antimicrobial substance production of the B. cereus strains against a panel of microorganisms was tested by well-diffusion assay. Five of the B. cereus strains, 1A, 4a, 6A, 9A and 10B, had moderate activity against diverse Gram-positive bacteria and certain Gram-negative bacteria. The most striking result was that most of the strains tested, particularly B. cereus I OB, were effective against Candida glabrata, C albicans, Geotrichum candidum and Botrytis cinerea.