Characterization of native Bacillus thuringiensis strains for cytotoxicity against human cancer cell lines

Abstract

Aim: The aim of this study was to characterize fourteen B. thuringiensis strains for cyt and parasporin gene contents as well as cytotoxicity of parasporal proteins against different cancer cell lines. Methodology: PCRwas applied for screening of cyt 1/cyt 2 and six different parasporin genes. In addition, cyt negative (non-cyf) nine Bt strains were tested for hemolytic activity. Non-cyt and non-hemolytic parasporal proteins from nine Bt strains were alkali solubilized and activated by proteinase-K for in vitro cytotoxic activities. Results: Five Bt strains carried cyt gene whereas only one strain Bt-Ba 14 harbored parasporin 2 gene and showed 37 kDa protein on SDS-PAGE. Non-cyf 9 Bt strains were confirmed to be non-hemolytic. MTT assay indicated that activated parasporal proteins (10 ?g ml -1 ) displayed selective cytotoxicity against HeLa, PC-3 and A549 cancer cell lines compared to a normal cell line BEAS-2B. Parasporal protein from Bt-Ba 14 exhibited the highest cytotoxicity against all three cancer cells, however, not to normal cell line and caused cytocidal activity similar to that observed with parasporins. Interpretation: The study reported that non-cyt and non-hemolytic Bt strains from Turkey have parasporal proteins with cytotoxic activities against cancer cells. © 2018 Triveni Enterprises, Lucknow (India).