FIG. 4.

Growth dependence of an L. lactis pyrP mutant on different pyrimidine compounds. The growth was monitored by determining colony size after 40 h of incubation at 30°C on SA-glucose plates with the indicated additions. The size of the largest colonies was arbitrarily set to 1. (A) Growth of MB417 (pyrP pyrB) on uracil (▵) and uridine (▴). The pyrF mutant PSA001 gave the same result with uracil and uridine as MB417 with uridine. Wild-type strain MG1363 was included as a control (●). (B) Growth of MB417 on uridine (16.4 μM) and increasing concentrations of 5-fluorouracil (▴). As controls pyrF mutant PSA001 (■) and wild-type strain MG1363 (□) were included. All curves intercept the y axis at 1.0.