Growth rates of some hisA mutant strains are increased by exogenous histidine.

Growth rates (in hours−1) are shown and are arranged in descending order by their ability to generate their own histidine (middle data column). All strains were grown in minimal glucose medium at 37°C with adenine and the indicated additions. Thi: thiamine; His: histidineaNG = no growth; growth rate was −1.