Galactose transport in Clostridium acetobutylicum P262

N.A. GUTIERREZ AND I.S. MADDOX. 1996. Evidence is provided that there are two separate systems for galactose uptake in Clostridium acetobutylicum P262, a phosphoenolpyruvate‐dependent phosphotransferase system and a proton motive force‐driven system. Glucose uptake involves the former but not the latter. When present on their own in a semi‐synthetic medium, glucose and galactose were consumed by the bacterium at rates of 1.00 mmol 1−1 h−1 and 0.79 mmol 1−1 h−1, respectively. However, when present as a mixture, glucose was used preferentially, and there was a lag period before galactose utilization commenced. The subsequent consumption rates were 0.97 mmol 1−1 h−1 and 0.38 mmol 1−1 h−1, for glucose and galactose, respectively. These data provide evidence for repression of galactose utilization by glucose.