Macromolecular evaluation of growth in electricity-producing biofilms: Current production of G. sulfurreducens biofilms grown in graphite electrodes is related to the physiological state of biofilm

SCHROTT GD; ORDOÑEZ MV; BUSALMEN JP

Norwich

Conferencia; Electron transfer at the microbe-mineral interface; 2012

University of East Anglia

G. sulfurreducens can use extracellular insoluble electron acceptor during anaerobic respiration. It can also use a polarized electrode for this function thus producing an electric current. Elucidating mechanisms behind these modes of respiration is significant for the development of clean energy and waste treatment, which are still under discussion. Besides this, controlling steps in current production are thought to be at the metabolic activity of cells and remain to be determined. In this work we profiled the content of macromolecules relevant for evaluating the population physiology and growth, over the development of Geobacter sulfurreducens biofilms on polarized graphite electrodes. DNA accumulation served as direct measurement of cell number, while protein content allowed biomass quantification. The RNA/DNA ratio on the other hand, was taken as a good indicator for the physiological state of biofilms. Contrasting macromolecular data with current production reveled typical phases along the biofilm growth, including lag, exponential and stationary growth phases. Importantly, current is not related to biomass accumulation as previously suggested, but to the physiological state of biofilms as indicated by the RNA/DNA ratio. Supported by European Commission (7th framework program, BacWire proyect)