Abstract

We investigated the role of green sulfur bacteria inlight-responsive electricity generation in microbial electrochemical cells (MXCs). We operated MXCs containing either monocultures or defined cocultures of previously enriched phototrophic Chlorobium and anode-respiring Geobacter under anaerobic conditions in the absence of electron donor. Monoculture control MXCs containing Geobacter or Chlorobium neither responded to light nor produced current, respectively. Instead, light-responsive current generation occurred only in coculture MXCs. Current increased above background levels only in the dark and declined slowly over 96h. This pattern suggested that Chlorobium exhausted intracellular glycogen reserves via dark fermentation to supply an electron donor, presumably acetate, to Geobacter. With medium containing sulfide as the sole photosynthetic electron donor, current generation had a similar and reproducible negative light response. To investigate whether this metabolic interaction also occurred without an electrode, we performed coculture experiments in batch serum bottles. In this setup, sulfide served as the sole electron donor, whose oxidation by Chlorobium was required to provide S0 as the electron acceptor to Geobacter. Copies of Geobacter 16S rDNA increased approximately 14-fold in batch bottle cocultures containing sulfide compared to those lacking sulfide, and did not decline after termination of sulfide feeding. These results suggest that products of both photosynthesis and dark fermentation by Chlorobium were sufficient both to yield an electrochemical response by Geobacter biofilms, and to promote Geobacter growthin batch cocultures. Our work expands upon the fusion of MXCs with coculture techniques and reinforces the utility of microbial electrochemistry for sensitive, real-time monitoring of microbial interactions in which a metabolic intermediate can be converted to electrical current.

Original languageEnglish (US)
Pages (from-to)223-231
Number of pages9
JournalBiotechnology and Bioengineering
Volume111
Issue number2
DOIs
StatePublished - Feb 2014

Fingerprint

Geobacter
Electricity
Chlorobium
Sulfides
Coculture Techniques
Metabolism
Electrons
Bottles
Fermentation
Light
Electrodes
Electrochemical cells
Photosynthesis
Chlorobi
Biofilms
Electrochemistry
Microbial Interactions
Ribosomal DNA
Glycogen
Sulfur

Keywords

  • Coculture
  • Fermentation
  • Glycogen
  • Microbial electrochemical cell
  • Photosynthesis

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Applied Microbiology and Biotechnology
  • Medicine(all)

Cite this

Coupling dark metabolism to electricity generation using photosynthetic cocultures. / Badalamenti, Jonathan P.; Torres, Cesar; Krajmalnik-Brown, Rosa.

In: Biotechnology and Bioengineering, Vol. 111, No. 2, 02.2014, p. 223-231.

Research output: Contribution to journalArticle

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