Sensitivity of the Purify-and-Patch Method.

aStrain FC40. bStrain SMR6277. This strain and FC40 are shown not to have different frequencies of secondary mutations when assayed by the same method (Table S1). cThis result probably does not mean that the frequency of auxotrophs was less than 9×10−5 (1/10,687) but rather that the method of direct transfer via replica plating is particularly ill suited to detection of phenotypes that result in the inability to form a colony.