Anaerobic n-alkane metabolism by a sulfate-reducing bacterium, Desulfatibacillum aliphaticivorans strain CV2803T.
The alkane-degrading, sulfate-reducing bacterium Desulfatibacillum 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. aliphaticivorans 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.
Laboratoire de Microbiologie, Géochimie et Ecologie Marines, UMR CNRS 6117, Centre d'Océanologie de Marseille (OSU), Campus de Luminy, case 901, 13288 Marseille cedex 09, France.
Cristiana
C
Cravo-Laureau
Vincent
V
Grossi
Danielle
D
Raphel
Robert
R
Matheron
Agnès
A
Hirschler-Réa
D000473:Alkanes / Q000378:metabolism*; D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D003470:Culture Media; D020564:Deltaproteobacteria / Q000254:growth & development* / Q000302:isolation & purification / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism; D019015:Geologic Sediments / Q000382:microbiology; D012623:Seawater / Q000382:microbiology; D016999:Sulfur-Reducing Bacteria / Q000254:growth & development* / Q000302:isolation & purification / Q000378:metabolism*
D000473:Alkanes; D003470:Culture Media; D005227:Fatty Acids; C007932:n-hexadecane