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Necessity of electrically conductive pili for methanogenesis with magnetite stimulation.

ABSTRACT: Background:Magnetite-mediated direct interspecies electron transfer (DIET) between Geobacter and Methanosarcina species is increasingly being invoked to explain magnetite stimulation of methane production in anaerobic soils and sediments. Although magnetite-mediated DIET has been documented in defined co-cultures reducing fumarate or nitrate as the electron acceptor, the effects of magnetite have only been inferred in methanogenic systems. Methods:Concentrations of methane and organic acid were analysed with a gas chromatograph and high-performance liquid chromatography, respectively. The concentration of HCl-extractable Fe(II) was determined by the ferrozine method. The association of the defined co-cultures of G. metallireducens and M. barkeri with magnetite was observed with transmission electron micrographs. Results:Magnetite stimulated ethanol metabolism and methane production in defined co-cultures of G. metallireducens and M. barkeri; however, magnetite did not promote methane production in co-cultures initiated with a culture of G. metallireducens that could not produce electrically conductive pili (e-pili), unlike the conductive carbon materials that facilitate DIET in the absence of e-pili. Transmission electron microscopy revealed that G. metallireducens and M. barkeri were closely associated when magnetite was present, as previously observed in G. metallireducens/G. sulfurreducens co-cultures. These results show that magnetite can promote DIET between Geobacter and Methanosarcina species, but not as a substitute for e-pili, and probably functions to facilitate electron transfer from the e-pili to Methanosarcina. Conclusion:In summary, the e-pili are necessary for the stimulation of not only G. metallireducens/G. sulfurreducens, but also methanogenic G. metallireducens/M. barkeri co-cultures with magnetite.

SUBMITTER: Wang O

PROVIDER: S-EPMC5866715 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Necessity of electrically conductive pili for methanogenesis with magnetite stimulation.

Wang Oumei O Zheng Shiling S Wang Bingchen B Wang Wenjing W Liu Fanghua F

PeerJ 20180321

<h4>Background</h4>Magnetite-mediated direct interspecies electron transfer (DIET) between <i>Geobacter</i> and <i>Methanosarcina</i> species is increasingly being invoked to explain magnetite stimulation of methane production in anaerobic soils and sediments. Although magnetite-mediated DIET has been documented in defined co-cultures reducing fumarate or nitrate as the electron acceptor, the effects of magnetite have only been inferred in methanogenic systems.<h4>Methods</h4>Concentrations of m ...[more]

PMID: 29576990

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Necessity of electrically conductive pili for methanogenesis with magnetite stimulation.

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Necessity of electrically conductive pili for methanogenesis with magnetite stimulation.

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