Biodegradation of acenaphthene by Sphingobacterium sp. strain RTSB involving trans-3-carboxy-2-hydroxybenzylidenepyruvic acid as a metabolite.

A gram-negative bacterium designated as RTSB was isolated from a petroleum-contaminated soil competent of utilizing acenaphthene as the solitary source of carbon and energy. The strain RTSB was identified as a Sphingobacterium species based on the morphological, nutritional and biochemical features of the organism as well as 16S rRNA sequence analysis. By a combination of chromatographic and spectrometric techniques, different metabolites of the acenaphthene degradation pathway by the strain RTSB were isolated and identified, which indicate a novel acenaphthene degradation pathway involving 1-naphthoic acid. Characterization of different metabolites suggested transformation of acenaphthene to 1-naphthoic acid through 1-acenaphthenol, acenaphthenequinone and naphthalene-1,8-dicarboxylic acid in the upper pathway of degradation; while in the later, 1-naphthoic acid was processed via a novel meta-cleavage pathway, leading to the formation of trans-3-carboxy-2-hydroxybenzylidenepyruvic acid, and then to salicylic acid and catechol entering into the TCA cycle intermediates. This detailed study of acenaphthene degradation by a Sphingobacterium species describes a distinct pathway of acenaphthene degradation involving the novel metabolite trans-3-carboxy-2-hydroxybenzylidenepyruvic acid.