The microbial degradation of cyclohexanecarboxylic acid: a pathway involving aromatization to form p-hydroxybenzoic acid

Abstract

A strain of Arthrobacter catabolizes cyclohexanecarboxylic acid by a pathway involving aromatization of the ring before its cleavage. The pathway includes the following intermediates: trans-4-hydroxycyclohexanecarboxylic acid, 4-ketocyclohexanecarboxylic acid, p-hydroxybenzoic acid, protocatechuic acid, and β-ketoadipic acid. The oxidation of 4-hydroxycyclohexanecarboxylic acid by cell extracts specifically requires NAD+ and results in the production of 4-ketocyclohexanecarboxylic acid. The latter compound is oxidized in the presence of a suitable electron acceptor, such as oxygen, methylene blue, or 2,6-dichlorophenolindophenol, to p-hydroxybenzoic acid.