Use of Electrochemistry to Monitor the Growth and Activity of Clostridium phytofermentans

Microbes have a wide range of metabolic capabilities available that make them industrially useful organisms. Monitoring these metabolic processes is a crucial component in efficient industrial application. Unfortunately, monitoring these metabolic processes is often invasive and time consuming especially within an anaerobic environment. Electrochemical techniques, such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) offer a non-invasive approach to monitor microbial activity and growth. We hypothesized that EIS and CV could be used to monitor Clostridium phytofermentans, an anaerobic and endospore-forming bacterium. C. phytofermentans ferments a wide range of sugars into hydrogen, acetate, and ethanol as fermentation by-products and is a good candidate for consolidated bioprocesses. For this study, both traditional microbiological and electrochemical techniques were used to monitor the growth of C. phytofermentans and the formation of fermentation products. An irreversible reduction peak was observed using CV beginning at mid-logarithmic phase of growth. This peak was associated with C. phytofermentans and not the spent medium. Additionally, EIS parameters, phase shift and imaginary admittance generally followed the growth of C. phytofermentans. Results suggest that CV and EIS are useful tools in the monitoring of C. phytofermentans and could possibly be used to monitor other anaerobic microbial processes