Methanogenic degradation of branched alkanes in enrichment cultures of production water from a high-temperature petroleum reservoir

Jing Chen, Yi Fan Liu, Lei Zhou, Serge Maurice Mbadinga, Tao Yang, Jing Zhou, Jin Feng Liu, Shi Zhong Yang, Ji Dong Gu, Bo Zhong Mu*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

Branched alkanes are important constituents of crude oil and are usually regarded as resistant to microbial degradation, resulting in little knowledge of biochemical processes involved in anaerobic branched alkanes biodegradation. Here, we initiated an incubation study by amendment of iso-C9 (2-methyl, 3-methyl, and 4-methyloctane) as substrates for methanogenic degradation in production water from a high-temperature petroleum reservoir. Over an incubation period of 367 days, significant methanogenesis was observed in samples amended with these branched alkanes. The strong methanogenic activity only observed in iso-C9 amendments suggested the presence of microbial transformation from iso-alkanes into methane. GC-MS-based examination of the original production water identified an intermediate tentatively to be iso-C9-like alkylsuccinate, but was not detected in the enrichment cultures, combined with the successful amplification of assA functional gene in inoculating samples, revealing the ability of anaerobic biodegradation of iso-C9 via fumarate addition pathway. Microorganisms affiliated with members of the Firmicutes, Synergistetes, and methanogens of genus Methanothermobacter spp. were highly enriched in samples amended with iso-C9. The co-occurrence of known syntrophic acetate oxidizers Thermoacetogenium spp. and Methanothermobacter spp. (known hydrogenotrophic methanogens) indicates a potential syntrophic acetate oxidation associated with the methanogenic biodegradation of iso-C9. These results provide some useful information on the potential biodegradation of branched alkanes via methanogenesis and also suggest that branched alkanes are likely activated via fumarate addition in high-temperature petroleum reservoirs.

Original languageEnglish
Pages (from-to)2391-2401
Number of pages11
JournalApplied Microbiology and Biotechnology
Volume103
Issue number5
DOIs
StatePublished - 1 Mar 2019
Externally publishedYes

Keywords

  • Alkylsuccinate
  • assA gene
  • High-temperature petroleum reservoir
  • iso-Alkanes or branched alkanes
  • Methanogenic degradation

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