Anaerobic degradation of 2-methylnaphthalene by a sulfate-reducing enrichment culture.
Anaerobic degradation of 2-methylnaphthalene was investigated with a sulfate-reducing enrichment culture. Metabolite analyses revealed two groups of degradation products. The first group comprised two succinic acid adducts which were identified as naphthyl-2-methyl-succinic acid and naphthyl-2-methylene-succinic acid by comparison with chemically synthesized reference compounds. Naphthyl-2-methyl-succinic acid accumulated to 0.5 microM in culture supernatants. Production of naphthyl-2-methyl-succinic acid was analyzed in enzyme assays with dense cell suspensions. The conversion of 2-methylnaphthalene to naphthyl-2-methyl-succinic acid was detected at a specific activity of 0.020 +/- 0.003 nmol min(-1) mg of protein(-1) only in the presence of cells and fumarate. We conclude that under anaerobic conditions 2-methylnaphthalene is activated by fumarate addition to the methyl group, as is the case in anaerobic toluene degradation. The second group of metabolites comprised 2-naphthoic acid and reduced 2-naphthoic acid derivatives, including 5,6,7,8-tetrahydro-2-naphthoic acid, octahydro-2-naphthoic acid, and decahydro-2-naphthoic acid. These compounds were also identified in an earlier study as products of anaerobic naphthalene degradation with the same enrichment culture. A pathway for anaerobic degradation of 2-methylnaphthalene analogous to that for anaerobic toluene degradation is proposed.
Annweiler
E
E
Institut für Biogeochemie und Meereschemie, Universität Hamburg, D-20146 Hamburg, Germany.
Materna
A
A
Safinowski
M
M
Kappler
A
A
Richnow
H H
HH
Michaelis
W
W
Meckenstock
R U
RU
D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D019735:Carbon-Carbon Ligases / Q000378:metabolism; D017753:Ecosystem; D005618:Fresh Water / Q000382:microbiology*; D019015:Geologic Sediments / Q000382:microbiology; D009281:Naphthalenes / Q000378:metabolism*; D010084:Oxidation-Reduction; D013431:Sulfates / Q000378:metabolism*
D009281:Naphthalenes; D013431:Sulfates; D019735:Carbon-Carbon Ligases; C419830:naphthyl-2-methyl-succinate synthase; C027384:2-methylnaphthalene