Degradation of anthracene by Mycobacterium sp. strain LB501T proceeds via a novel pathway, through o-phthalic acid

Abstract

Mycobacterium sp. strain LB501T utilizes anthracene as a sole carbon and energy source. We analyzed cultures of the wild-type strain and of UV-generated mutants impaired in anthracene utilization for metabolites to determine the anthracene degradation pathway. Identification of metabolites by comparison with authentic standards and transient accumulation of o-phthalic acid by the wild-type strain during growth on anthracene suggest a pathway through o-phthalic acid and protocatechuic acid. As the only productive degradation pathway known so far for anthracene proceeds through 2,3-dihydroxynaphthalene and the naphthalene degradation pathway to form salicylate, this indicates the existence of a novel anthracene catabolic pathway in Mycobacterium sp. LB501T.

FIG. 1.

Proposed degradation pathway for anthracene by Mycobacterium sp. strain LB501T. Compounds D and E were identified tentatively, the compound in a closed box (C) was identified by comparison with a spectrum from the literature, and the compounds between brackets were not identified in our samples. A to F, compounds found in peaks A to F of GC-MS chromatograms.

FIG. 2.

Concentration of OPA in cultures of Mycobacterium sp. LB501T growing on anthracene (OPA) in comparison with the biomass production (optical density [OD]). The bacterial controls and the chemical controls showed no formation of OPA. Duplicate cultures yielded similar results.