Cytotoxic function of endotoxins produced by middle Tennessee isolates of Bacillus thuringiensis against Aedes albopictus cell line CCL-126
Bacillus thuringiensis is an endospore-forming bacterium characterized by the production of a protein crystal toxin called δ-endotoxin during sporulation. A given strain will normally synthesize between one and five of these toxins packaged into single or multiple crystals. The presence of a parasporal crystal and insecticidal activity are some of the most distinguishing features of the bacterium. In this study, Bacillus thuringiensis isolates previously recovered from Middle Tennessee were cultured to stationary phase on a differential media containing 1% glucose. The insecticidal crystal proteins of B. thuringiensis were characterized suing SDS-PAGE. Isolates that were found to be spherical in shape were tested against Aedes mosquito larvae ATCC CCL-126 Aedes albopictus mosquito midgut epithelial cells. Bioassays performed under standard conditions indicated differential tolerance levels. The bioassays indicate that exposure to Bacillus thuringiensis Suspensions of the toxins resulted in LC50 values ranging from 1.66x10-8μg/mL to 1.33x10 -3μg/mL which were deleterious to Aedes larvae. Midgut cells were exposed to various concentrations of proteins and viability and cytotoxicity were measured using the Promega MultiTox-Fluor Multiplex Cytotoxicity Assay after 24 hours of exposure. A kill curve was established. Suspensions of several of the toxins resulted in more than a 50% decrease in the viability of the mosquito cells. The findings suggest an optimal concentration of toxin is necessary to quickly and effectively kill mosquito midgut cells.
Karen Lenoir Burke,
"Cytotoxic function of endotoxins produced by middle Tennessee isolates of Bacillus thuringiensis against Aedes albopictus cell line CCL-126"
ETD Collection for Tennessee State University.