FIG. 4.

Growth of various strains under specific culture conditions. Cultures of B. subtilis strains CYBS400 (wild type), CYBS223 (ΔmtrB), CYBS542 (↑AT), and CYBS318 (ΔrtpA) were grown in Vogel-Bonner minimal medium with the various supplements indicated plus 0.5% glucose and trace elements at 37°C. Cell density was determined hourly by using a Klett-Summerson colorimeter. Klett units were plotted versus time to obtain the growth curves shown. (A) Growth with or without 100 μg/ml Trp. (B) Growth with 50 μg/ml Phe with or without 100 μg/ml Trp. (C) The mtrB gene was deleted from the genome of the B. subtilis strain BS166 trpE26. Growth rates were determined for cultures of strains BS166 trpE26 and BS166 trpE26 ΔmtrB, as shown in panel A. Cultures were grown with the supplements indicated in the figure: 100 μg/ml Trp with or without 50 μg/ml Phe and 50 μg/ml Tyr.