Thaxtomin A (1) and B (2), the two major phytotoxins associated with the common scab of potato disease, were transformed into C-14 linked beta-glucosides (3) and (4), respectively, when individually incubated with cultures of Bacillus mycoides in oatmeal broth at 26 degrees C. These biotransformation products when assayed on aseptically produced potato minitubers proved to be much less phytotoxic than the parent compounds.