The enhanced ability of A1501 to degrade benzoate by 4-hydroxybenzoate. (A) Time course of bacterial growth in the presence of 4 mM benzoate (black triangle) or a mixture of 4 mM benzoate and 0.4 mM (clear triangle) or 0.8 mM (clear dot) 4-hydroxybenzoate. (B) The benzoate consumption when A1501 was cultured in minimal medium containing 4 mM benzoate (black dot) or a mixture of 4 mM benzoate and 0.4 mM 4-hydroxybenzoate (clear dot), and changes in 4-hydroxybenzoate concentrations (clear diamond) were detected by HPLC. (C) The formation of catechol derived from benzoate (black square) or a mixture of benzoate and 4-hydroxybenzoate (clear square). Samples were collected at different times and the amount of the aromatic compound in the culture supernatant was determined by HPLC.