FIG. 1.

Early steps in the catabolism of phthalate by gram-negative bacteria and A. keyseri 12B and the transformation of 2-substituted benzoates by A. keyseri 12B. (a) Phthalate catabolic pathway in gram-negative bacteria; (b) phthalate catabolic pathway in A. keyseri 12B; (c) 2-substituted benzoate transformation in A. keyseri 12B. Chemicals; I, o-phthalate; II, cis-4,5-dihydroxy-4,5-dihydrophthalate; III, 4,5-dihydroxyphthalate; IV, protocatechuate; V, cis-3,4-dihydroxy-3,4-dihydrophthalate; VI, 3,4-dihydroxyphthalate; VII, 2-substituted benzoate; VIII, 2-substituted 3,4-dihydroxy-3,4-dihydrobenzoate; IX, 2-substituted protocatechuate. For dihydrodiols, cis but not absolute stereochemistry is intended. R = -CHO and -COOCH₃ (prior to this study) and -CF₃, -Cl, -Br, -I, -NO₂, -COCH₃, and -OCH₃ (this study). Enzymes: A1, phthalate 4,5-dioxygenase; B1, cis−4,5-dihydroxy-4,5-dihydrophthalate dehydrogenase; Cl, 4,5-dihydroxyphthalate decarboxylase; A2, phthalate 3,4-dioxygenase; B2, cis-3,4-dihydroxy-3,4-dihydrophthalate dehydrogenase; C2, 3,4-dihydroxyphthalate 2-decarboxylase.