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The alkane- and alkene-degrading, marine sulfate-reducing bacterium Desulfatibacillum aliphaticivorans strain CV2803 is examined for its 1-alkene metabolism. The pathways have indicated that diverse initial reactions of 1-alkene activation have occurred simultaneously in the same strain of sulfate-reducing bacterium.

Research was conducted to examine the anaerobic degradation of aliphatic hydrocarbon. Hexadecan-2-one, nonadecan-10-one and two pristane photooxidation products were studied under sulfate-reucing conditions. Acting as the sole source of carbon and energy, both hexadecan-2-one and 6,10,14-trimethylpentaecan-2-one were able to grow a microbial enrichment culture from marine sediment. Results confirm the importance of the community of sulfate-reducing bacteria in anoxic environments and in the degradation of hydrocarbons.

The hydrocarbon fraction of leaf waxes of three halophytes of the Chenopodiaceae common to Mediterranean salt marshes (Suaeda vera, Sarcocornia fruticosa and Halimione portulacoides) revealed the presence of a minor series of odd and even chains 1-chloro-n-alkanes ranging from C19 to C29. The identification of these new chlorinated plant constituents was based on a combination of mass spectrometry data with selective chlorine detection (CPG-AED) and was confirmed by comparison with authentic standards. The qualitative and quantitative distributions of these 1-chloro-n-alkanes varied inter-specifically. Homologues with an odd carbon-chain were predominant in all species but maximised at C25 and C27 in S. vera and S. fruticosa, and at C27 and C29 in H. portulacoides. Remarkably, 1-chloro-nonacosane was an abundant homologue only in this latter species. Leaves of S. vera contained 4 to 7 times more of total chloroalkanes than leaves of the other two species. These compounds accounted for 10, 4 and 1% of the hydrocarbon fraction of leaf waxes of S. vera, S. fruticosa and H. portulacoides, respectively. Attempts to link the occurrence of these chloroalkanes with other classes of leaf waxes (n-alkenes, n-aldehydes and n-alcohols) did not allowed a clear precursor–product relationship to be established. The biological functions as well as the mode of synthesis of alkylchlorides in (halophyte) plants remain unknown but undoubtedly deserve further attention. [Copyright &y& Elsevier]

Presents a study to analyze anaerobic degradation of hexadecan-2-one by a microbial enrichment culture under sulfate-reducing conditions. Details on materials and methodology used to conduct study; Indication of findings; Discussion on results.

The alkane-degrading, sulfate-reducing bacterium Desulfatibadillum aliphaticivorans strain CV2803T, recently isolated from marine sediments, was investigated for n-alkane metabolism. The total cellular fatty acids of this strain had predominantly odd numbers of carbon atoms (C odd) when the strain was grown on a C-odd alkane (pentadecane) and even numbers of carbon atoms (C even) when it was grown on a C-even alkane (hexadecane). Detailed analyses of those fatty acids by gas chromatography/mass spectrometry allowed us to identify saturated 2-, 4-, 6-, and 8-methyl- and monounsaturated 6-methyl-branched fatty acids, with chain lengths that specifically correlated with those of the alkane. Growth of D. aliphaticivorans on perdeuterated hexadecane demonstrated that those methyl -branched fatty acids were directly derived from the substrate. In addition, cultures on pentadecane and hexadecane produced (1-methyltetradecyl) succinate and (1-methylpentadecyl) succinate, respectively. These results indicate that D. aliphalicivorans strain CV2803T oxidizes n-alkanes into fatty acids anaerobically, via the addition of fumarate at C-2. Based on our observations and on literature data, a pathway for anaerobic n-alkane metabolism by D. aliphaticivorans is proposed. This involves the transformation of the initial alkylsuccinate into a 4-methyl-branched fatty acid which, in addition to catabolic reactions, can alternatively undergo chain elongation and desaturation to form storage fatty acids. [ABSTRACT FROM AUTHOR]