Publications (3)38.83 Total impact
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ABSTRACT: The short-chain hydrocarbons ethane, propane and butane are constituents of natural gas. They are usually assumed to be of thermochemical origin, but biological formation of ethane and propane has been also observed. Microbial utilization of short-chain hydrocarbons has been shown in some aerobic species but not in anaerobic species of bacteria. On the other hand, anaerobic utilization of short-chain hydrocarbons would in principle be expected because various anaerobic bacteria grow with higher homologues (> or =C(6)). Indeed, chemical analyses of hydrocarbon-rich habitats with limited or no access of oxygen indicated in situ biodegradation of short-chain hydrocarbons. Here we report the enrichment of sulphate-reducing bacteria (SRB) with such capacity from marine hydrocarbon seep areas. Propane or n-butane as the sole growth substrate led to sediment-free sulphate-reducing enrichment cultures growing at 12, 28 or 60 degrees C. With ethane, a slower enrichment with residual sediment was obtained at 12 degrees C. Isolation experiments resulted in a mesophilic pure culture (strain BuS5) that used only propane and n-butane (methane, isobutane, alcohols or carboxylic acids did not support growth). Complete hydrocarbon oxidation to CO2 and the preferential oxidation of 12C-enriched alkanes were observed with strain BuS5 and other cultures. Metabolites of propane included iso- and n-propylsuccinate, indicating a subterminal as well as an unprecedented terminal alkane activation with involvement of fumarate. According to 16S ribosomal RNA analyses, strain BuS5 affiliates with Desulfosarcina/Desulfococcus, a cluster of widespread marine SRB. An enrichment culture with propane growing at 60 degrees C was dominated by Desulfotomaculum-like SRB. Our results suggest that diverse SRB are able to thrive in seep areas and gas reservoirs on propane and butane, thus altering the gas composition and contributing to sulphide production.Nature 10/2007; 449(7164):898-901. · 36.28 Impact Factor
Article: Polymer-supported ferrocenyl oxazolines for the catalyzed highly enantioselective phenyl transfer to aldehydes.[show abstract] [hide abstract]
ABSTRACT: A new chiral MeO-PEG-supported ferrocenyl oxazoline was synthesized and successfully employed in the enantioselective phenyl transfer to aldehydes. The products were obtained in high yields and with excellent enantioselectivities (up to 97% ee). Furthermore, the recovery of the ferrocene was facile, and catalyst efficiency was maintained in subsequent reactions.Bioorganic & Medicinal Chemistry Letters 08/2002; 12(14):1795-8. · 2.55 Impact Factor
Article: Formation of n-alkane- and cycloalkane-derived organic acids during anaerobic growth of a denitrifying bacterium with crude oil[show abstract] [hide abstract]
ABSTRACT: The formation of metabolites during anaerobic biodegradation of saturated hydrocarbons directly from crude oil in the absence of oxygen was investigated using a denitrifying bacterium, the Azoarcus-like strain HxN1, which can utilise C6–C8n-alkanes anaerobically as growth substrates. Various alkylsuccinates (apparently diastereomers) with alkyl chains (probably linked at C-2) ranging from C4 to C8 were detected by gas chromatography–mass spectrometry. These metabolites apparently result from the activation reaction of C4–C8 alkanes with cellular fumarate, analogous to the recently established reaction of pure n-hexane with fumarate in strain HxN1 to yield (1-methylpentyl)succinate. Other succinates carried substituents derived from cyclopentane and methylcyclopentane and hence indicated an activation of such cycloalkanes. Since n-butane, n-pentane or cycloalkanes as single compounds did not support growth of strain HxN1, their apparent products point to co-metabolic reactions during utilisation of the C6–C8n-alkanes. Furthermore, methyl-branched and cyclopentyl-substituted fatty acids were detected. This finding is explained by a further metabolism of the substituted succinates via carbon skeleton rearrangement and decarboxylation. All metabolites detected in the oil-grown cultures were also identified in cultures grown with defined mixtures of saturated hydrocarbons. Results are of potential value for an understanding of metabolite formation in hydrocarbon-rich anoxic environments from the viewpoint of bacterial physiology.Organic Geochemistry.