Spheroidal forms of Bacillus megaterium induced by potassium tellurite.

This communication is concerned with the formation of spheroidal bodies from Bacillus megaterium strain KM, by the action of potassium tellurite in a hypertonic sucrose medium. Cells grown in sucrose-casein hydrolyzate broth (Lederberg and St. Clair, J. Bacteriol., 75, 143, 1958) were inoculated into fresh broth and aerated at 37 C for 3 to 4 hr. Potassium tellurite (final concentration 0.05 per cent) was added to the cultures during the exponential growth phase. The cultures were placed in a candle jar and incubated under semianaerobic conditions for 18 hr at room temperature. Light microscopic examinations revealed many spheroidal bodies containing deposits of tellurium. With the electron microscope it may be seen that these deposits of tellurium are in the form of individual fine crystals peripherally disposed, and in clusters of crystals in local cytoplasmic sites contiguous