Fermentative Spirochaetes mediate necromass recycling in anoxic hydrocarbon-contaminated habitats

Xiyang Dong, Chris Greening, Thomas Brüls, Ralf Conrad, Kun Guo, Svenja Blaskowski, Farnusch Kaschani, Markus Kaiser, Nidal Abu Laban, Rainer U. Meckenstock

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57 Citations (Scopus)


Spirochaetes are frequently detected in anoxic hydrocarbon- and organohalide-polluted groundwater, but their role in such ecosystems has remained unclear. To address this, we studied a sulfate-reducing, naphthalene-degrading enrichment culture, mainly comprising the sulfate reducer Desulfobacterium N47 and the rod-shaped Spirochete Rectinema cohabitans HM. Genome sequencing and proteome analysis suggested that the Spirochete is an obligate fermenter that catabolizes proteins and carbohydrates, resulting in acetate, ethanol, and molecular hydrogen (H2) production. Physiological experiments inferred that hydrogen is an important link between the two bacteria in the enrichment culture, with H2 derived from fermentation by R. cohabitans used as reductant for sulfate reduction by Desulfobacterium N47. Differential proteomics and physiological experiments showed that R. cohabitans utilizes biomass (proteins and carbohydrates) released from dead cells of Desulfobacterium N47. Further comparative and community genome analyses indicated that other Rectinema phylotypes are widespread in contaminated environments and may perform a hydrogenogenic fermentative lifestyle similar to R. cohabitans. Together, these findings indicate that environmental Spirochaetes scavenge detrital biomass and in turn drive necromass recycling at anoxic hydrocarbon-contaminated sites and potentially other habitats.

Original languageEnglish
Pages (from-to)2039-2050
Number of pages12
JournalThe ISME Journal
Issue number8
Publication statusPublished - 30 May 2018

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