title: Biological role of gramicidin S in spore functions. Studies on gramicidin-S-negative mutants of Bacillus brevis ATCC9999.
abstract: Gramicidin-S-negative mutants of Bacillus brevis ATCC9999 have been isolated with a remarkly higher yield after ethidium bromide or acridine orange treatment, than after N-methyl-N'-nitro-N-nitrosoguanidine treatment. Four (MIV, Smr170, R5 and EB 16) of 38 isolated mutants were characterized with respect to the lesion in gramicidin-S-synthesizing activity. The mutants sporulate to the same extent as the parental strain except mutant Smr 170 which sporulates less. However, mutant spores were more heat-sensitive and possessed a reduced level of dipicolinic acid content. No significant difference was observed in the germination time of wild-type and mutant spores. All spores germinated after 80--110 min, but the outgrowth time was different: all gramicidin-S-negative mutants grew out immediately after germination whereas wild-type spores required a lag period of 9--10 h. When the mutants were allowed to sporulate in the presence of gramicidin S, the spores were found to be heat-resistant and their outgrowth postponed to the same period as the parent spores. The addition of gramicidin also eliminated the deficiency of dipicolinic acid. A new class of gramicidin-S-negative mutant, R5, which only activates L-valine and L-leucine, is described. A possible biological function of gramicidin S in the heat-resistance and in the timing of spore outgrowth is discussed.
mesh_terms: D000165:Acridine Orange / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001407:Bacillus / Q000187:drug effects / Q000502:physiology*; D011756:Diphosphates / Q000378:metabolism; D004996:Ethidium / Q000494:pharmacology; D006096:Gramicidin / Q000494:pharmacology*; D007700:Kinetics; D008769:Methylnitronitrosoguanidine / Q000494:pharmacology; D009154:Mutation; D013171:Spores, Bacterial / Q000187:drug effects / Q000502:physiology
chemical_list: D000900:Anti-Bacterial Agents; D011756:Diphosphates; D008769:Methylnitronitrosoguanidine; D006096:Gramicidin; D000255:Adenosine Triphosphate; D004996:Ethidium; D000165:Acridine Orange