We explore the utility of microbial electrochemical cells (MXCs) as microbiological tools for investigation of novel anoxygenic photosynthetic bacteria capable of current production.  After following a selective enrichment strategy for phototrophs and against traditional anode-respiring bacteria (ARB), we interrogated the phototrophic bacterial communities for extracellular electron transfer (EET) capabilities by varying exposure to light.  In multiple inocula, we observed sharp decreases in current production by phototrophs in the light, suggesting that cells switched between phototrophic and dark anaerobic respiratory metabolism, with phototrophy being the preferred route for ATP generation.  Current densities reached maximum values of ~1 A m-2 in the dark, and cyclic voltammograms, when fit to the Nernst-Monod model, revealed anode respiration kinetics that differed from non-phototrophic ARB.  Microbial community analyses showed dominance of anoxygenic phototrophs in anode biofilms.  In summary, our results strongly suggest direct current production by phototrophic bacteria on the anode.

Using microbial electrochemical cells for selective enrichment of novel current-producing anoxygenic photosynthetic bacteria

243rd National Meeting (2012)

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