Miniaturized systems for evaluating enzyme activity in polymeric membrane bioreactors.

Enzyme-coated polymeric membranes are versatile catalysts for biofuel production and other chemical production from feedstock, like plant biomass. Such bioreactors are more energy efficient than high temperature methods because enzymes catalyze chemical reactions near room temperature. A major challenge in processing plant biomass is the presence of lignin, a complex aromatic polymer that resists chemical breakdown. Therefore, membranes coated with enzymes such as laccase that can degrade lignin are sought for energy extraction systems. We present an experimental study on optimizing an enzyme-based membrane bioreactor and investigate the tradeoff between high flow rate and short dwell time in the active region. In this work, zero flow rate voltammetry experiments confirm the electrochemical activity of laccase on conductive polymer electrodes, and a flow-through spectroscopy device with laccase-coated porous nylon membranes is used with a colorimetric laccase activity indicator to measure the catalysis rate and percent conversion as a function of reactant flow rate. Membrane porosity before and after laccase coating is verified with electron microscopy.