Biochemical studies of bacterial sporulation and germination. XXII. Energy metabolism in early stages of germination of Bacillus megaterium spores.

Dormant spores of Bacillus megaferium contain DPN+, TPN+, and FAD at levels comparable to those in log phase vegetative cells, but little or no reduced pyridine nucleotides are present. The levels of free nucleotides, the most abundant of which are the adenine nucleotides, are also similar in spores and cells. In cells, however, 80% of the adenine nucleotide pool is ATP, whereas in spores it is less than 1%. During germination, ATP levels develop in three stages. Within the first 5 min (Stage I), there is a sharp increase derived from the 3-phospho-D-glyceric acid depot and also from exogenous metabolites if available. The level is maintained for about 15 min (Stage II) by endogenous or exogenous metabolites. In Stage III, the ATP level increases as a result of biosynthesis of adenine nucleotides, and exogenous carbon and phosphate sources are required. The pathways of energy metabolism are aerobic and cyanide-sensitive in Stages II and III, and the enzymes required for energy metabolism in all three stages are previously formed and present in the dormant spore.