The Formation of Tetracycline in Date Medium by Mutants of Streptomyces aureofaciens Induced by Nitrosogiuanidine.

The present study deals with the genotoxicity of Nitrosoguanidine (N.T.G.) - a chemical mutagen- which was employed to induce auxotrophic mutations in the haploid wild type of bacteria Streptomyces aureofaciens strain NCIMB 8234. An increase in exposure time to the mutagen and dose of this mutagen led to a decrease in the survival percentage and increase in the percentage of mutation. The mutants were cultured in synthetic date fermentation medium, which contained Barni date-coat sugar extract as a carbon source. The following parameters were determined: final pH, medium quantity, and microbial cell biomass. All of the five mutants produced less antibiotic titers than the initial organism this was noticed after measuring the inhibition zone of each created for Staphylococcus aureus as a gram-positive pathogenic bacterium and Escherichia coli as a gram- negative pathogenic bacterium.