Effect of doping pretreated corn stover conditions on yield of bioethanol in immobilized cell systems

The surface characteristics of immobilized yeast before and after adding CO2-laser pretreated corn stover (LPCS) substrates were investigated using bioethanol production. Response surface methodology (RSM), based on the Box-Behnken design (BBD) for experiments, was used to optimize the doping condition. An optimum experimental condition was obtained at pH 4.5, 2.08% yeast concentration, and 0.20% LPCS substrates. Under this condition, doping LPCS increased the yield of bioethanol from 53% to 84%, which matched the predicted value. After doping LPCS, the results of inverted microscope (IM) and atomic force microscopy (AFM) illustrated that the immobilized gel beads changed from rod-like in shape with a smooth surface to a larger rod-like ultrastructure with a rougher surface. The yield was relatively stable within 28 d, with a downward trend subsequently appearing.