The Biological Activity of Some Extracted Proteins from Bacillus spp. Isolated from Soil Against Pathogenic Bacteria

Abstract

Forty soil samples were collected from different regions in Baghdad city. Among 52 isolate, only 38 isolates (73.1 %) belong to Bacillus spp. All bacterial isolates have been submitted to the cultural, microscopical, biochemical examination and VITEK 2 System, Bacillus cereus was predominantly found 21 (55.3%) followed by Bacillus subtilis 11 (28.9%), then Bacillus amyloliquefaciens was 6 (15.8%). Bacillus cereus (B1) and Bacillus subtilis (B16) isolates were with the highest level with the antibacterial activity when selected. Extracellular proteins were extracted and purified with ammonium sulfate (80%) saturation, then submitted to Sepharose-6B gel filtration column. SDS-polyacrylamide gel electrophoresis was used to determine the molecular weights of proteins, and one band appeared to each of Bacillus cereus and Bacillus subtilis with molecular weight 68 and 50 KDa respectively. The results revealed that higher effect of antibacterial activity on Gram positive bacteria, and moderate on Gram negative bacteria except P.aeruginosa with no effect. The antibiofilm effect of the extract found higher effective against S.pyogens, moderate effect against each of (S.aureus, E.coli, S. marcescens, K. spp) and no effect against P.aeruginosa. The results of cytotoxicity showed that the purified extract was a higher cytotoxic effect on breast cancer MCF7 cells at 1000µg/ml concentration, while the crude extract had a higher cytotoxic effect on breast cancer MCF7 cells at 100µg/ml concentration.