Mycotoxin bioassay, using Bacillus stearothermophilus.

Spores of Bacillus stearothermophilus in standardized spore strips are pretreated with solutions of the mycotoxins aflatoxin B1, patulin, rubratoxin B, and diacetoxyscirpenol and subsequently incubated in a nutrient solution containing bromocresol purple as pH indicator. After 16.5 hr of inclubation the color of the indicator medium inoculated with untreated spore strips of B. stearothermophilus changes from purple to yellow; no color change occurs in the indicator medium inoculated with spore strips treated 15 min with 0.01 mug of any of the 4 mycotoxins/ml during a 60 hr incubation.