Studies of a Purine-Requiring Mutant Strain of Escherichia Coli. Ii. Selection of Revert Strains and Its Evolutionary Significance

Abstract

N a previous publication (GUTHRIE 1949), certain characteristics of a purine-1 requiring mutant strain of Escherichia coli, 9661-01, were described, including its ability to undergo reversion (change to purine-independence, or P+ ) as shown by optimal growth at suboptimal concentrations of purine. Reversion occurred much more frequently in a complex medium (B) than in a minimal glucose-salts medium (A).This report includes studies of selection between the P (9661-01 parent)