Formation of competent Bacillus subtilis cells

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Abstract
The process of competent cell formation for transformation was studied with early-stationary-phase (T1) cells of B. subtilis which had been grown in an enriched Spizizen minimal medium and transferred to a 2nd synthetic medium. Rifampin, chloramphenicol and tunicamycin were strong inhibitors of competent cell formation and vegetative growth. After formation, competent cells were no longer sensitive to the above agents. Methicillin and an inhibitor of chromosomal repication, hydroxyphenylazouracil, did not inhibit the development of competence. A D-alanine-requiring mutant strain developed competence even in the absence of D-alanine in the 2nd medium. A T1-stage culture showed the activity of extracellular serine protease which is necessary for sporulation. Competent cell formation was completely blocked by 0.7 M ethanol, which is a specific inhibitor of early events during sporulation including forespore septum formation. Competent cells were formed even in media which supported sporulation. The development of competence was also studied with spo0 mutants at 10 different loci. Most spo0 mutations repressed the development of competence except for spo0C, spo0G and spo0J. Competent cells apparently are formed from early sporulating cells with the synthesis of cell wall materials and by factors which genes are activated by the supply of nutrients. Common steps may be involved both in forespore septation and in competent cell formation.