Sulfure requirement for postgerminative development of Bacillus megaterium spores.

In Bacillus megaterium, the transition from bacterial spore to vegetative cell has been divided into phases of germination, swelling, emergence, elongation, and cell division. This has been demonstrated both in simple (Levinson and Hyatt, 1956) and in complex (Mandels et al., 1956) media, the primary tool for quantitative measurement being the change in respiratory rate accompanying each new developmental phase. Germination, roughly equivalent to "prevegetation" (Jensen, 1950) and to "step a" in the developmental sequence of Schmidt (1955), is defined as the spore's initial loss of heat resistance accompanied by increased metabolic activity; stainability with methylene blue; and loss of refractility. The appearance of translucent areas (Hachisuka et al., 1955) may also be a criterion of germination. We describe later stages as "postgerminative development," or simply "development," which is equivalent to "outgrowth" as used by O'Brien and Campbell (1956). The nutritional requirements for postgerminative development are not known. Spores germinate rapidly in a neutral phosphate buffered medium containing L-alanine and glucose, or MnSO4 and glucose, but in the former medium they fail to develop further. MnSO4 appears to act in a dual role, stimulating rapid initial germination and promoting postgerminative development. The present study was initiated to elucidate further this dual role of MnSO4. It was found that while Mn+ meets a requirement for rapid spore germination, S04is necessary for development subsequent to germination. S04= is replaceable by other inorganic and organic sources of sulfur. Co++ and Ni+ are inhibitory to postgerminative development, their effects being evident at different stages.