Metabolic biomarkers for monitoring anaerobic naphthalene biodegradation in situ

Abstract

During the anaerobic biodegradation of naphthalene and methylnaphthalene, unique metabolites are formed by specific microbial carboxylation and ring-reduction reactions. Groundwater samples from an anoxic, shallow aquifer contaminated with gasoline were examined for the presence of these metabolites by extraction, derivatization and gas chromatography coupled to mass spectroscopy. Several metabolites [2-naphthoic acid (2-NA), tetrahydro-2-naphthoic acid (TH-2-NA), hexahydro-2-naphthoic acid (HH-2-NA) and methylnaphthoic acid (MNA)] were found to be present in the groundwater samples. The concentration of 2-NA at each monitoring well was quantified and correlated to the zones of contamination. The presence of the other metabolites in the same wells as 2-NA was used as confirmation that the anaerobic pathway was indeed active. The distribution of metabolites at this site shows that they can be used as biomarkers for demonstrating in situ biodegradation.

Degradation of o -xylene and m -xylene by a novel sulfate-reducer belonging to the genus Desulfotomaculum

“…3b) . The major fragments of these compounds were consistent with silylated 7-methylnaphthoic acid (Phelps et al 2002). These are strong indications that dimethylnaphthalenes can be co-metabolized with m-xylene as major organic substrate by strain OX39 at least to the stage of the respective methyl-naphthoic acid.…”

Intrinsic biodegradation potential of aromatic hydrocarbons in an alluvial aquifer – Potentials and limits of signature metabolite analysis and two stable isotope-based techniques

“…They need to be excluded as contaminants themselves in order to be indicative of on-site remediation (Phelps et al, 2002). In previous studies, various signature metabolites were either identified in batch culture experiments or were extracted from groundwater samples directly.…”

Genomic and mechanistic insights into the biodegradation of organic pollutants

“…Naphthalene and benzene are also degraded under anaerobic conditions, and even though pure cultures of naphthalene-degrading denitrifying Pseudomonas and Vibrio strains [38] and benzene-degrading denitrifying Dechloromonas strains [39] are available, the enzymes and genes involved in their anaerobic degradation are not known yet. Metabolic biomarkers suggest the degradation of naphthalene via attachment of a carboxylic acid group [40,41], but the metabolic route for benzene degradation remains to be elucidated [42 ].…”