Morphological alterations in Bacillus megaterium as produced by aflatoxin B1

Morphologically abnormal cells were produced by Bacillus megaterium NRRL B-1368 in response to aflatoxin B(1). Filamentous forms were characterized by early granulation and unusually large and numerous deposits of poly-beta-hydroxybutyric acid within the cells. Pantoyl lactone was without effect as a reversing agent for the observed inhibition of cell septum formation. B. megaterium cells and spores produced on toxic (3.8 mug of aflatoxin B(1) per ml) and nontoxic Trypticase Soy Broth and Trypticase Soy Agar (TSA) were observed by using phase contrast and electron microscopy. Transfer of aberrant forms to nontoxic TSA yielded macrocolonies with daughter cells morphologically indistinguishable from untreated cells. Agar slide cultures of filamentous cells transferred to nontoxic TSA indicated that normal cells were formed. Electron photomicrographs showed a decreased number of mesosomes in filamentous cells as compared to control cells. There were no observable morphological differences in spores formed on toxic or nontoxic TSA.