in the purine-deficient medium sf/azag , the 8-azaguanine-resistant mutant had the shortest doubling time , 61 min , followed by the two 6-mercaptopurine-resistant mutants ( sf/mpcc , 72 min ; sf/mp , 91 min ) , and finally the wild strain with a doubling time of 135 min .
C0034140
purine
C0000618
resistant