A variety of hydrogenotrophic enrichment cultures catalyse cathodic reactions

• Biocathodes where living microorganisms catalyse reduction of CO2 can potentially be used to produce valuable chemicals. Microorganisms harbouring hydrogenases may play a key role for biocathode performance since H-2 generated on the electrode surface can act as an electron donor for CO2 reduction. In this study, the possibility of catalysing cathodic reactions by hydrogenotrophic methanogens, acetogens, sulfate-reducers, denitrifiers, and acetotrophic methanogens was investigated. The cultures were enriched from an activated sludge inoculum and performed the expected metabolic functions. All enrichments formed distinct microbial communities depending on their electron donor and electron acceptor. When the cultures were added to an electrochemical cell, linear sweep voltammograms showed a shift in current generation close to the hydrogen evolution potential (-1 V versus SHE) with higher cathodic current produced at a more positive potential. All enrichment cultures except the denitrifiers were also used to inoculate biocathodes of microbial electrolysis cells operated with H+ and bicarbonate as electron acceptors and this resulted in current densities between 0.1-1A/m(2). The microbial community composition of biocathodes inoculated with different enrichment cultures were as different from each other as they were different from their suspended culture inoculum. It was noteworthy that Methanobacterium sp. appeared on all the biocathodes suggesting that it is a key microorganism catalysing biocathode reactions.

Subject headings

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Mikrobiologi inom det medicinska området (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Microbiology in the medical area (hsv//eng)

NATURVETENSKAP  -- Kemi -- Oorganisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Inorganic Chemistry (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Kemiteknik -- Annan kemiteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Chemical Engineering -- Other Chemical Engineering (hsv//eng)

NATURVETENSKAP  -- Biologi -- Mikrobiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Microbiology (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Miljöbioteknik -- Annan miljöbioteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Environmental Biotechnology -- Other Environmental Biotechnology (hsv//eng)

Keyword

extracellular electron-transfer

microbial electrosynthesis

desulfovibrio-gigas

methane production

acetate production

graphite

cathodes

mixed-culture

hydrogenase

conversion

reduction

Science & Technology - Other Topics

Publication and Content Type

ref (subject category)

art (subject category)