Spontaneous and Ultra-Violet-Induced Mutations to Phage Resistance in Escherichia Coli

Open Access
Publisher Website
Google Scholar
Abstract
A comparison between ultraviolet-induced mutations and spontaneous mutations with strain B/ r of E. coli and the use of T 1 bacteriophage as the selective agent has indicated some quantitative and qualitative differences. 114 ultraviolet-induced mutants and 164 B/r/1 strains resistant to phage T 1 and of independent origin were isolated. Only 8% of the induced group were resistant to phage T 1 but sensitive to T 5, as compared to 44% in the spontaneous. Moreover, all the mutants requiring a supplementary growth factor other than tryptophan were in the induced group and within this group single mutants required thiamine, tryptophan and tyrosine and phenyalanine, purines, serine and methionine. Unlike the spontaneous group, the greater part of the induced mutants did not require tryptophan, and this was true more in the mutation B/r-[forward arrow]B/r/l ,5. Also, the induced group contained a number of mutants which showed partial resistance of T 1 and these produced plaques, when exposed to certain phage concns.