Active Transport of Benzoate in Pseudomonas putida

SUMMARY: Benzoate uptake in Pseudomonas putida is mediated by an active transport system capable of accumulating benzoate against a 150-fold concentration gradient when subsequent metabolism is blocked by mutation. Initial benzoate transport rates are inhibited by CCCP, sodium azide, arsenate and DCCD. Uptake is stimulated by including a respirable carbon source during preincubation of the bacteria. The initial uptake rate and the ATP pool levels are not correlated and no periplasmic components were found to bind benzoate. These observations indicate that benzoate uptake is energized by the membrane potential, rather than by ATP hydrolysis.