The quantitative significance of Syntrophaceae and syntrophic partnerships in methanogenic degradation of crude oil alkanes

N. D. Gray*, A. Sherry, R. J. Grant, A. K. Rowan, C. R.J. Hubert, C. M. Callbeck, C. M. Aitken, D. M. Jones, J. J. Adams, S. R. Larter, I. M. Head

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

168 Citations (Scopus)

Abstract

Libraries of 16S rRNA genes cloned from methanogenic oil degrading microcosms amended with North Sea crude oil and inoculated with estuarine sediment indicated that bacteria from the genera Smithella (Deltaproteobacteria, Syntrophaceace) and Marinobacter sp. (Gammaproteobacteria) were enriched during degradation. Growth yields and doubling times (36 days for both Smithella and Marinobacter) were determined using qPCR and quantitative data on alkanes, which were the predominant hydrocarbons degraded. The growth yield of the Smithella sp. [0.020g(cell-C)/g(alkane-C)], assuming it utilized all alkanes removed was consistent with yields of bacteria that degrade hydrocarbons and other organic compounds in methanogenic consortia. Over 450 days of incubation predominance and exponential growth of Smithella was coincident with alkane removal and exponential accumulation of methane. This growth is consistent with Smithella's occurrence in near surface anoxic hydrocarbon degrading systems and their complete oxidation of crude oil alkanes to acetate and/or hydrogen in syntrophic partnership with methanogens in such systems. The calculated growth yield of the Marinobacter sp., assuming it grew on alkanes, was [0.0005 g(cell-C)/g(alkane-C)] suggesting that it played a minor role in alkane degradation. The dominant methanogens were hydrogenotrophs (Methanocalculus spp. from the Methanomicrobiales). Enrichment of hydrogen-oxidizing methanogens relative to acetoclastic methanogens was consistent with syntrophic acetate oxidation measured in methanogenic crude oil degrading enrichment cultures. qPCR of the Methanomicrobiales indicated growth characteristics consistent with measured rates of methane production and growth in partnership with Smithella.

Original languageEnglish
Pages (from-to)2957-2975
Number of pages19
JournalEnvironmental Microbiology
Volume13
Issue number11
Early online date14 Sep 2011
DOIs
Publication statusPublished - Nov 2011
Externally publishedYes

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