A Broad-Spectrum Antibacterial Activity of Lyophilized Crude Extracts of Bacillus Subtilis against Clinical and Food-Borne Pathogens

The aim of this research is to study the broad spectrum antibacterial activity of crude lyophilized extracts from Bacillus subtilis, then characterize these antibacterial activity. B. subtilis strains were isolated and identified by both API CHB 50 and molecular methods. Staphylococci strains, negative gram bacteria and Candida spp. were isolated from clinical and food samples and identified by biochemical and morphological tests. The crude antibacterial were extracted by flasks containing Lactose Broth LB, which incubated for 72 hours in shaker incubator at 37º ºC at 150 rev/min, then centrifuged 12000 rev/min or 15 min. at 4 ºC and filtrated the supernatants through 0.45 µm then frozen and lyophilized. The crude extracts were run on Diamonsil C18 column (5 µm, 250 × 4.6 mm) in HPLC system to separate the antibiotics and run on FTIR spectrum. Some strains of B. subtilis showed high activity against target strains, and others did not. The antibacterial activity of crude lyophilized extracts from B. subtilis (BS1A, BS2D, BS7SH, BS8SH ) against S. aureus strains was between high (16-40 mm) and intermediate (8-14 mm). While the antibacterial activity was intermediate (8-14 mm) against Gram negative and Candida spp. strains. Two kinds of antibiotics were separated from lyophilized extracts of B. subtilis and identified to the peptides families, Bacitracin A and Polymyxin B.