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Glucose Metabolism in a Microbial Fuel Cell. Stoichiometry of Product Formation in a Thionine-mediated Proteus vulgaris Fuel Cell and its Relation to Coulombic Yields
Abstract
The pattern of glucose metabolism was studied in a thionine-mediated Proteus vulgaris fuel cell by using 14C-labelled glucose. Added glucose was rapidly taken up by the bacteria and converted to CO2, acetate, lactate and a fourth product, tentatively identified as propionate. When the glucose-dependent electric current from the fuel cells had been completely discharged, about 50% of glucose carbon was found in CO2, 30% in acetate, 10% incorporated in the bacteria, and the residual 10% distributed as small amounts in various soluble products. Thus, although there was transient accumulation of lactate and ‘propionate’, these were largely reutilized. Coulombic yield from glucose oxidation was about 50% and correlated with the amount of CO2 produced. Glucose metabolism in the fuel cell was intermediate between conventional aerobic and anaerobic conditions. Under anaerobic (conventional) conditions acetate, lactate and ‘propionate’ were produced and not reutilized. Under aerobic conditions, acetate and lactate were only transiently produced and the rate of glucose uptake was lower. The major limitation on coulombic yield from glucose oxidation was the production of acetate.
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© Society for General Microbiology 1985