Metabolism of α-terpineol by Pseudomonas incognita

Abstract

Details of the metabolism of α-terpineol by Pseudomonas incognita are presented. Degradation of α-terpineol by this organism resulted in the formation of a number of acidic and neutral metabolites. Among the acidic metabolites, β-isopropyl pimelic acid, 1-hydroxy-4-isopropenyl-cyclohexane-1-carboxylic acid, 8-hydroxycumic acid, oleuropeic acid, cumic acid, and p-isopropenyl benzoic acid have been identified. Neutral metabolites identified were limonene, p-cymene-8-ol, 2-hydroxycineole, and uroterpenol. Cell-free extracts prepared from α-terpineol adapted cells were shown to convert α-terpineol, p-cymene-8-ol, and limonene to oleuropeic acid, 8-hydroxycumic acid, and perillic acid, respectively, in the presence of NADH. The same cell-free extract contained NAD+-specific dehydrogenase(s) which converted oleuropyl alcohol, p-cymene-7,8-diol, and perillyl alcohol to their corresponding 7-carboxy acids. On the basis of various metabolites isolated from the culture medium, together with the supporting evidence obtained from enzymatic and growth studies, it appears that P. incognita degrades α-terpineol by at least three different routes. While one of the pathways seems to operate via oleuropeic acid, a second may be initiated through the aromatization of α-terpineol. The third pathway may involve the formation of limonene from α-terpineol and its further metabolism.