RESUMEN
Sporulation and synthesis of bacitracin, a peptide antibiotic and serine exoproteases and endoproteases were studied in 6 strains of Bacillus licheniformis at various periods of cultivation in sporulation media. Thermostable spores in all the strains were shown to form in the absence of both the exogenic and endogenic antibiotic and proteases. It was suggested that bacitracin and the serine proteases were not specific regulators of sporogenesis in B. licheniformis and their biological function under the natural conditions included, respectively, the antibiotic action and hydrolysis of proteins and peptides of the environment and cells.
Asunto(s)
Bacillus/fisiología , Bacitracina/biosíntesis , Endopeptidasas/biosíntesis , Péptido Hidrolasas/biosíntesis , Bacillus/efectos de la radiación , Medios de Cultivo/metabolismo , Exopeptidasas , Mutación , Serina Endopeptidasas , Esporas Bacterianas/fisiología , Esporas Bacterianas/efectos de la radiación , Rayos UltravioletaRESUMEN
The vegetative cells of B. licheniformis, producing bacitracin, a feed grade peptide antibiotic were exposed to nitroso guanidine and six mutants with lowered activity of serine exoprotease in the culture fluid were isolated. It was found that synthesis of bacitracin and sporulation of the mutants were impaired. The cause of the impairment is not known. The results are discussed from two viewpoints: serine exoprotease is responsible for positive regulation of bacitracin biosynthesis and sporulation at the account of forming an amino acid pool in the medium, simultaneous changing of the three features in the mutants may be due either to a single pleiotropic mutation or to multiple mutations independently induced by nitroso guanidine.
Asunto(s)
Bacillus/enzimología , Bacitracina/biosíntesis , Mutación , Péptido Hidrolasas/metabolismo , Bacillus/genética , Bacillus/fisiología , Medios de Cultivo/metabolismo , Marcadores Genéticos , Esporas BacterianasRESUMEN
Ribosomal mutants of Bacillus subtilis IG2 and IG7 resistant to 100 mkg/ml of streptomycin have been isolated. The strA80 and strA88 mutations reduce the level of sporulation as well as antibiotic and proteolytic activity of bacteria. RNA polymerase mutations rfm20 and rfm146 transferred by transformation into ribosomal mutants suppress strA80 and strA88 mutations. As a result, sporulation was restored. Both mutations were cotransformed with cysA gene and mapped within the cluster of ribosomal and RNA polymerase genes. It is proposed that the ribosomal strA80 and strA88 mutations influence transcription of gene (s) which regulate initiation of sporulation and that the RNA polymerase rfm20 and rfm146 mutations can restore sporulation. The results suggest that ribosomes are most likely to be not able to play a specific role in sporulation and secondary metabolism of Bac. subtilis.