Naphthalene degradation and incorporation of naphthalene-derived carbon into biomass by the thermophile Bacillus thermoleovorans

The thermophilic aerobic bacterium Bacillus thermoleovorans Hamburg 2 grows at 60 degrees C on naphthalene as the sole source of carbon and energy. In batch cultures, an effective substrate degradation was observed. The carbo n balance, including naphthalene, metabolites, biomass, and CO2, was determ ined by the application of [1-C-13]naphthalene, The incorporation of naphth alene derived carbon into the bulk biomass as well as into specified biomas s fractions such as fatty acids and amino acids was confirmed by coupled ga s chromatographymass spectrometry (GC-MS) and isotope analyses. Metabolites were characterized by GC-MS; the established structures allow tracing the degradation pathway under thermophilic conditions. Apart from typical metab olites of naphthalene degradation known from mesophiles, intermediates such as 2,3-dihydroxynaphthalene, 2-carboxycinnamic acid, and phthalic and benz oic acid were identified for the pathway of this bacterium. These compounds indicate that naphthalene degradation by the thermophilic B, thermoleovora ns differs from the known pathways found for mesophilic bacteria.