Direct exchange of electrons within aggregates of an evolved syntrophic coculture of anaerobic bacteria.
Microbial consortia that cooperatively exchange electrons play a key role in the anaerobic processing of organic matter. Interspecies hydrogen transfer is a well-documented strategy for electron exchange in dispersed laboratory cultures, but cooperative partners in natural environments often form multispecies aggregates. We found that laboratory evolution of a coculture of Geobacter metallireducens and Geobacter sulfurreducens metabolizing ethanol favored the formation of aggregates that were electrically conductive. Sequencing aggregate DNA revealed selection for a mutation that enhances the production of a c-type cytochrome involved in extracellular electron transfer and accelerates the formation of aggregates. Aggregate formation was also much faster in mutants that were deficient in interspecies hydrogen transfer, further suggesting direct interspecies electron transfer.
Department of Microbiology, University of Massachusetts, Amherst, MA 01003, USA.
Zarath M
ZM
Summers
Heather E
HE
Fogarty
Ching
C
Leang
Ashley E
AE
Franks
Nikhil S
NS
Malvankar
Derek R
DR
Lovley
D000693:Anaerobiosis; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005075:Biological Evolution; D003470:Culture Media; D003574:Cytochrome c Group / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004579:Electron Transport; D004583:Electrons; D000431:Ethanol / Q000378:metabolism; D036781:Fimbriae Proteins / Q000235:genetics / Q000378:metabolism; D045302:Geobacter / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D006859:Hydrogen / Q000378:metabolism; D059013:Microbial Consortia / Q000502:physiology*; D056265:Microbial Interactions; D009154:Mutation; D010084:Oxidation-Reduction; D012641:Selection, Genetic
D001426:Bacterial Proteins; D003470:Culture Media; D003574:Cytochrome c Group; D036781:Fimbriae Proteins; D000431:Ethanol; D006859:Hydrogen