A facultative anaerobic bacterium was isolated from a mediator-less microbial fuel cell fed with artificial wastewater containing acetate and designated as PA3. The isolate was identified as a strain of Aeromonas hydrophila based on its biochemical, physiological and morphological characteristics as well as 16S rDNA sequence analysis and DNA-DNA hybridization. PA3 used glucose, glycerol, pyruvate and hydrogen to reduce Fe(III), nitrate and sulfate. Cyclic voltammetry showed that PA3 was electrochemically active and was the culture collection strain A. hydrophila KCTC 2358. Electricity was generated from a fuel cell-type reactor, the anode compartment of which was inoculated with cell suspensions of the isolate or A. hydrophila KCTC 2358. The electrochemical activities are novel characteristics of A. hydrophila.

A fuel cell-type electrochemical device has been used to enrich microbes oxidizing acetate with concomitant electricity generation without using an electron mediator from activated sludge. The device generated a stable current of around 5 mA with complete oxidation of 5 mM acetate at the hydraulic retention time of 2.5 h after 4 weeks of enrichment. Over 70% of electrons available from acetate oxidation was recovered as current. Carbon monoxide or hydrogen did not influence acetate oxidation or current generation from the microbial fuel cell (MFC). Denaturing gradient gel electrophoresis showed that DNA extracted from the acetate-enriched MFC had different 16S rDNA patterns from those of sludge or glucose+glutamate-enriched MFCs. Nearly complete 16S rDNA sequence analyses showed that diverse bacteria were enriched in the MFC fed with acetate. Electron microscopic observations showed biofilm developed on the electrode, but not microbial clumps observed in MFCs fed with complex fuel such as glucose and wastewater from a corn-processing factory.

Recent determination of genome sequences for a wide range of bacteria has made in-depth knowledge of prokaryotic metabolic function essential in order to give biochemical, physiological, and ecological meaning to the genomic information. Clearly describing the important metabolic processes that occur in prokaryotes under different conditions and in different environments, this advanced text provides an overview of the key cellular processes that determine bacterial roles in the environment, biotechnology, and human health. Prokaryotic structure is described as well as the means by which nutrients are transported into cells across membranes. Glucose metabolism through glycolysis and the TCA cycle are discussed, as well as other trophic variations found in prokaryotes, including the use of organic compounds, anaerobic fermentation, anaerobic respiratory processes, and photosynthesis. The regulation of metabolism through control of gene expression and control of the activity of enzymes is also covered, as well as survival mechanisms used under starvation conditions.