FIG. 2.

Chemotactic responses of P. putida TW3 (A) and Pseudomonas sp. strain 4NT (B) in smooth swimming response assays after growth with 10 mM succinate, 5 mM benzoate, or saturating amounts of 4-nitrobenzoate (4NB) or 4-nitrotoluene (4NT). The response in this assay is the amount of time in seconds needed for approximately 50% of the cells to adapt to the added attractant. The abbreviations for the attractants in the chemotaxis buffer are as follows: 0.2% CAA, 0.2% Casamino Acids; Ben, benzoate; 4NB, 4-nitrobenzoate; 3NB, 3-nitrobenzoate; 4AB, 4-aminobenzoate; 3AB, 3-aminobenzoate; 2AB, 2-aminobenzoate. No response was seen with chemotaxis buffer alone or with 1 mM 2-nitrobenzoate (data not shown).