SULFUR REQUIREMENT FOR POSTGERMINATIVE DEVELOPMENT OF BACILLUS MEGATERIUM SPORES

Abstract

In B. megaterium, the transition from spore to vegetative cell is divided into stages of germination and postgerminative development. Germination refers to the initial changes in this transition and includes an increase in metabolic activity, loss of heat resistance, loss of retractility, and increased stainability with methylene blue. The postgerminative development stages are swelling of the spore, emergence, elongation and cell division, each phase being marked by a different linear rate of O2 consumption. While L-alanine greatly stimulates the germination of B. megaterium spores in glucose, no postgerminative development occurs. MnSCO4 appears to act in a dual role, stimulating germination and promoting subsequent postgerminative development. While Mn++ meets a requirement for rapid spore germination, SO4= is necessary for postgerminative development. SO4= is replaceable by other inorganic and organic sources of sulfur. The low concentration of S (3.2 ppm) required to exert a maximum effect and the immediate response of germinated spores to the addition of S, indicate its utilization in the synthesis of substances active in catalysis (enzymes, coenzymes). Spore germination is not stimulated or inhibited by the cations, K+, Mg++, Zn++, Cu++, Fe++, Co++, and Ni++. Of these, only Co++ or Ni++ inhibit postgerminative development. Co++ is inhibitory to stages of postgerminative development prior to emergence, but not to elongation or cell-division. Ni++ is inhibitory to all stages except cell division. This difference in site of inhibitory effect may offer a tool for separation of the metabolic requirements of each post-germinative stage of development.