Degradation of pyrene by an enteric bacterium, Leclercia adecarboxylata PS4040

Abstract

A newly discovered enteric bacterium Leclercia adecarboxylata PS4040, isolated from oily sludge contaminated soil sample was reported for degradation of polycyclic aromatic hydrocarbons (Appl Environ Microbiol 70:3163-3166, 2004a). This strain could degrade 61.5% of pyrene within 20 days when used as sole source of carbon and energy. The time course degradation experiment detected several intermediate products and the metabolites were identified by gas chromatography mass spectrometry analysis. Metabolite I was the detected on the 5th day and was identified as 1-hydroxypyrene and was detected till 10th day. Metabolite II which was detected on 10th day was identified as 1,2-phenanthrenedicarboxylic acid. Metabolite III and Metabolite IV were identified as 2-carboxy benzaldehyde and ortho-phthalic acid, respectively and were detected in the culture broth on 10th and 15th day. 1,2-benzene diol (catechol) was the fifth metabolite detected in the culture extracts on the 15th day and was subsequently reduced on day 20. Identification of Metabolite I as 1-hydroxypyrene was further investigated as this intermediate was not previously reported as a ring oxidation product for degradation of pyrene by bacterial strains. Purification by preparative high performance liquid chromatography and nuclear magnetic resonance spectroscopy, confirmed the identification of Metabolite I as 1-hydroxypyrene. L. adecarboxylata PS4040 could also use 1-hydroxypyrene as a sole source of carbon and energy. Thus a probable pathway for degradation of pyrene by enteric bacterium is proposed in this study, with 1-hydroxypyrene as initial ring oxidation product.