Example 1
Thuricide BT Caterpillar Control (Southern Ag) was used as the source of viable Bacillus thuringiensis spores (6 million spores/mg). The DEE chemical comprised of 1:200 bleach in water. This concentration corresponds to approximately 0.5 wt.-% bleach (Clorox) in water. Vegetative cells of BT were grown in lysogeny broth for 48 h at 30° C. The culture was diluted 1:100 with phosphate buffered saline and the DEE chemical composition (about 100 microliters) was added. In the case of spores, the DEE composition was added to achieve a 1:100 dilution of spores.
The spores and vegetative cells in a micro-centrifuge tube were then exposed to 2.45 GHz microwave radiation for 10 s. After exposure, the cells were centrifuged and washed to remove the DEE composition and then plated on Petrifilm and cultured. The plates were then cultured for 24 h at 30° C. This decontamination method resulted in 6-7 log reduction in BT vegetative cells. However, in the case of BT spores, only 4-5 log kill was realized. Increasing the microwave exposure time to 15-20 s yielded 6-7 log kill levels in the case of BT spores.
