Anaerobic naphthalene degradation by a sulfate-reducing enrichment culture.
Anaerobic naphthalene degradation by a sulfate-reducing enrichment culture was studied by substrate utilization tests and identification of metabolites by gas chromatography-mass spectrometry. In substrate utilization tests, the culture was able to oxidize naphthalene, 2-methylnaphthalene, 1- and 2-naphthoic acids, phenylacetic acid, benzoic acid, cyclohexanecarboxylic acid, and cyclohex-1-ene-carboxylic acid with sulfate as the electron acceptor. Neither hydroxylated 1- or 2-naphthoic acid derivatives and 1- or 2-naphthol nor the monoaromatic compounds ortho-phthalic acid, 2-carboxy-1-phenylacetic acid, and salicylic acid were utilized by the culture within 100 days. 2-Naphthoic acid accumulated in all naphthalene-grown cultures. Reduced 2-naphthoic acid derivatives could be identified by comparison of mass spectra and coelution with commercial reference compounds such as 1,2,3, 4-tetrahydro-2-naphthoic acid and chemically synthesized decahydro-2-naphthoic acid. 5,6,7,8-Tetrahydro-2-naphthoic acid and octahydro-2-naphthoic acid were tentatively identified by their mass spectra. The metabolites identified suggest a stepwise reduction of the aromatic ring system before ring cleavage. In degradation experiments with [1-(13)C]naphthalene or deuterated D(8)-naphthalene, all metabolites mentioned derived from the introduced labeled naphthalene. When a [(13)C]bicarbonate-buffered growth medium was used in conjunction with unlabeled naphthalene, (13)C incorporation into the carboxylic group of 2-naphthoic acid was shown, indicating that activation of naphthalene by carboxylation was the initial degradation step. No ring fission products were identified.
Meckenstock
R U
RU
Department of Biology, University of Konstanz, D-78457 Konstanz, Germany. rainer.meckenstock@uni-konstantz.de
Annweiler
E
E
Michaelis
W
W
Richnow
H H
HH
Schink
B
B
D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D003470:Culture Media; D005618:Fresh Water / Q000382:microbiology; D008401:Gas Chromatography-Mass Spectrometry; D009281:Naphthalenes / Q000378:metabolism*; D013431:Sulfates / Q000378:metabolism; D016999:Sulfur-Reducing Bacteria / Q000254:growth & development / Q000378:metabolism*; D014876:Water Pollution
D003470:Culture Media; D009281:Naphthalenes; D013431:Sulfates; C031721:naphthalene; C030037:2-naphthoic acid