Abstract
A total of 407 samples were collected from the western region of Saudi Arabia. Soil samples as well as dead larvae of Spodoptera littoralis (cotton leaf worm) were collected and examined for the presence of Bacillus thuringiensis. The bacterium was isolated using an acetate-selective enrichment medium and plating. The isolates that were collected by the above-mentioned protocol were identified by using a combination of both microscopic examinations as well as the analysis of 16S rRNA genes through DNA sequencing of PCR products. A total of 22 confirmed isolates of Bacillus thuringiensis were identified for the purpose of this study. Collectively, these confirmed isolates make up 4.6% of all soil samples and 6.6% of all dead larvae samples that were collected. Although B. thuringiensis was not found to be abundant in soil habitats of The Makkah Province, our results suggest that the bacterium is the part of the indigenous microflora of the area that we explored in this study. Preliminary results show that the partially purified crystal protein of some of the isolates exhibits demonstrable activity against three human cancer cell lines: Hep G2 (human liver carcinoma cell line), HeLa cells (human uterine cervix cancer cell line), and Vero cells (lung cancer Cell line).