微生物および生化学技術ジャーナル

概要

Use of Bacterial Cellulose from Gluconacetobacter hansenii NOK21 as a Proton-permeable Membrane in Microbial Fuel Cells

Young Hwan Ko, Hwa Jeong Oh and Hyun Jung Lee

An acetic acid bacterium NOK21 from the pellicle on the surface of rancid wine was isolated and identified as Gluconacetobacter hansenii based on morphological, physiological, and genetic characteristics. When the bacterial isolate was grown in static broth containing ethanol, a maximum pellicle concentration of 5.2 g/? was obtained at 3% ethanol concentration and a maximum acidity of 3.97% was reached at 5% ethanol concentration. At ethanol concentrations higher than 6%, no bacterial growth was observed. Analysis with solid state 13C-NMR spectroscopy showed that the pellicle from the NOK21 culture was composed of a relatively pure cellulose polymer and had a few carboxylate (COO-) groups. Also, observation of the pellicle with SEM revealed a multi-layer network structure where nano-diameter cellulose fibers were tangled together at random. The pellicle cellulose polymer was used as a proton-permeable membrane in a microbial fuel cell (MFC) and had about a 3-fold higher efficiency for electric power generation than a cation exchange membrane Neosepta CMX. Moreover, electric power was generated stably at 150-200 mW/m2 per anode surface area. These results suggest that the microfibril cellulose membrane from the NOK21 culture may be suitable for use as an alternative to expensive proton exchange membranes in MFCs.