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.
Cravo-Laureau
Cristiana
C
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.
Grossi
Vincent
V
Raphel
Danielle
D
Matheron
Robert
R
Hirschler-Réa
Agnès
A
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