Microbial Electrochemical Cells as a Research Tool to Probe Microbial and Biofilm Kinetics
Abstract:Anode-respiring bacteria (ARB) are known to produce electrical current from organic compounds and wastes in microbial electrochemical cells (MXCs). Recent kinetic experiments show that the current generated by ARB is not hindered by extracellular electron transfer; thus, it directly measures their respiration rate in real time. Given the high precision of electrical current measurements, determining the respiration rate of ARB gives scientists and engineers a new tool to study microbial and biofilm kinetics. We outline three experiments that were performed using electrochemical measurements. First, we tracked the growth of ARB in a biofilm to measure their specific growth rate (μ). Our results show an 18% decrease in μ as the biofilm developed. The capability to track respiration rates in the ARB biofilm over various orders of magnitude allows us to track these changes in growth during biofilm development. Second, we measured the rate of endogenous decay for an ARB biofilm by measuring the current generated with no electron donor. We tracked how this rate decreased with time over a 5-day period. After this period, extracellular polymeric substances (EPS) were significantly decreased within the biofilm, as shown by scanning electron microscopy. Third, we observed the kinetic response of an ARB biofilm after the addition of butyrate, a fermentable substrate. The current density increased within a few seconds of butyrate addition, suggesting that butyrate can partially be consumed directly by ARB. These experiments are examples of the electrochemical measurements that can be performed to probe microbial and biofilm kinetics.
Document Type: Research Article
Publication date: January 1, 2010
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