Metabolic Requirements for Microcycle Sporogenesis of Bacillus megaterium

Germinated spores ofBacillus subtilis were incubated in outgrowth medium and tested periodically for capacity to sporulate when suspended in sporulation medium. Concurrent measurements were made of deoxyribonucleic acid (DNA) content and numbers of cell division septa and nucleoids. Sporulation potential is shown to reach a peak at about 110 min, at which time the chromosomes are probably well into the second round of replication. Experiments with nalidixic acid show that sporulation potential can be generated in the outgrowth medium even when DNA synthesis is largely prevented. Further experiments show that nalidixic acid apparently does not prevent the formation of DNA initiation complexes, which can subsequently function after resuspension in the sporulation medium. The results support those previously obtained with a temperaturesensitive DNA mutant which indicated that sporulation could only be induced at a specific stage of chromosome replication, and then only if the cells are in a state of nutritional "step-down."

Section: Discussionmentioning

confidence: 79%

Section: Discussionmentioning

confidence: 99%

Resporulation of outgrowing Bacillus subtilis spores

Keynan¹,

Berns²,

Dunn³

et al. 1976

“…Such "microcycle" spores have been shown to be produced by a process which is cytologically identical with the process which occurs after growth (15). Microcycle sporogenesis can be induced by limitation of the phosphate in the medium (28,29), and the minimal organic requirements seem to be acetate and a catalytic amount of a tricarboxylic acid cycle intermediate (22).…”

Section: Resultsmentioning

confidence: 99%

Minimal Requirements for Commitment to Sporulation in Bacillus megaterium

Greene

Slepecky

1972

Commitment to sporulation was examined by means of both endotrophic sporulation and rejuvenation experiments. In both cases, a point of commitment to the completion of sporulation occurred at stage II. With 2 x 108 cells/ml, the process by which commitment occurred required 0.5 mm Mg2+, 10.0 mm phosphate, and an energy source (minimum of 5.0 mm acetate). For completion of sporulation and formation of normal, heat-resistant refractile spores, 0.3 mM Ca2+ was required. Except for this Ca2+ requirement, the completion of sporulation after commitment was independent of the nature of the surrounding medium. Some aspects of the utilization of these required substances were examined. 557 on August 1, 2020 by guest http://jb.asm.org/ Downloaded from T,,, the time at which refractility would be complete if the cells had been allowed to complete sporulation in the original medium (18). It was found that endotrophic sporulation was also complete at this time (to stage VI [18]). 558

“…Holmes and Levinson (17) showed that nitrate limitation induced microcycle sporogenesis in B. megaterium, and MacKechnie and Hanson (19) found that microcycle sporogenesis of B. cereus resulted from phosphate limitation. These results were consistent with a hypothesis that catabolite repression involved an effector containing nitrogen and phosphate.…”

mentioning

confidence: 99%

Adenine Nucleotide Changes Associated with the Initiation of Sporulation in Bacillus subtilis

Hutchison

Hanson

1974

At the end of the exponential growth phase of Bacillus subtilis, there is a decrease in the energy level of the cell, whether expressed as adenosine triphosphate concentration or adenylate energy charge. Phosphate limitation of exponentially growing cells produces a similar decrease in the energy level of the cell, and sporulation is derepressed in the presence of 10 mM glucose. A reduction in the tryptophan concentration of the medium during phosphate limitation of the tryptophan auxotroph B. subtilis 168 prevented the decrease in energy charge. Cells do not sporulate under these conditions. Energy charge values of 0.30 to 0.35 found during sporulation do not lead to cell death.Endospore formation in bacteria has been recognized as a response to a lack of nutrients since 1890 (2). Grelet (12) showed that sporulation of Bacillus megaterium occurred when on August 1, 2020 by guest