title: Anaerobic 1-alkene metabolism by the alkane- and alkene-degrading sulfate reducer Desulfatibacillum aliphaticivorans strain CV2803T.
abstract: The alkane- and alkene-degrading, marine sulfate-reducing bacterium Desulfatibacillum aliphaticivorans strain CV2803(T), known to oxidize n-alkanes anaerobically by fumarate addition at C-2, was investigated for its 1-alkene metabolism. The total cellular fatty acids of this strain were predominantly C-(even number) (C-even) when it was grown on C-even 1-alkenes and predominantly C-(odd number) (C-odd) when it was grown on C-odd 1-alkenes. Detailed analyses of those fatty acids by gas chromatography-mass spectrometry after 6- to 10-week incubations allowed the identification of saturated 2- and 4-ethyl-, 2- and 4-methyl-, and monounsaturated 4-methyl-branched fatty acids with chain lengths that correlated with those of the 1-alkene. The growth of D. aliphaticivorans on (per)deuterated 1-alkenes provided direct evidence of the anaerobic transformation of these alkenes into the corresponding 1-alcohols and into linear as well as 10- and 4-methyl-branched fatty acids. Experiments performed with [(13)C]bicarbonate indicated that the initial activation of 1-alkene by the addition of inorganic carbon does not occur. These results demonstrate that D. aliphaticivorans metabolizes 1-alkene by the oxidation of the double bond at C-1 and by the subterminal addition of organic carbon at both ends of the molecule [C-2 and C-(omega-1)]. The detection of ethyl-branched fatty acids from unlabeled 1-alkenes further suggests that carbon addition also occurs at C-3. Alkylsuccinates were not observed as potential initial intermediates in alkene metabolism. Based on our observations, the first pathways for anaerobic 1-alkene metabolism in an anaerobic bacterium are proposed. Those pathways indicate that diverse initial reactions of 1-alkene activation can occur simultaneously in the same strain of sulfate-reducing bacterium.
authors.affiliation: Paléoenvironnements et Paléobiosphère, UMR5125 PEPS CNRS, Université Lyon 1, Campus de la Doua, Bâtiment Géode, 69622 Villeurbanne Cedex, France. vincent.grossi@univ-lyon1.fr
authors.forename: Vincent
authors.initials: V
authors.lastname: Grossi
authors.forename: Cristiana
authors.initials: C
authors.lastname: Cravo-Laureau
authors.forename: Alain
authors.initials: A
authors.lastname: Méou
authors.forename: Danielle
authors.initials: D
authors.lastname: Raphel
authors.forename: Frédéric
authors.initials: F
authors.lastname: Garzino
authors.forename: Agnès
authors.initials: A
authors.lastname: Hirschler-Réa
mesh_terms: D000438:Alcohols / Q000378:metabolism; D000473:Alkanes / Q000378:metabolism*; D000693:Anaerobiosis; D001639:Bicarbonates / Q000378:metabolism; D002250:Carbon Radioisotopes / Q000378:metabolism; D020564:Deltaproteobacteria / Q000254:growth & development / Q000378:metabolism*; D005227:Fatty Acids / Q000032:analysis / Q000737:chemistry; D008401:Gas Chromatography-Mass Spectrometry; D010084:Oxidation-Reduction; D013431:Sulfates / Q000378:metabolism*
chemical_list: D000438:Alcohols; D000473:Alkanes; D001639:Bicarbonates; D002250:Carbon Radioisotopes; D005227:Fatty Acids; D013431:Sulfates