Effect of Membrane Entrapment on Enzyme Activity in Enzymatic Treatment for Bioethanol Production

A team of researchers from Taiwan (Institute of Biological Chemistry & Genomic Research Center, Academia Sinica; Department of Food Science, Fu Jen Catholic University; and Institute of Biochemical Sciences, College of Life Science, National Taiwan University) and Thailand (Division of Biochemical Technology, School of Bioresources and Technology, King Mongkut's University of Technology) recently investigated the effect of membrane entrapment on enzyme activity in the enzymatic treatment step of bioethanol production. Enzymatic treatment is the second step in bioethanol production (after pretreatment) in which enzymes break carbohydrate molecules down into the component monosaccharides. However, due to the high cost of enzymes, it is important to increase enzyme activity to lower the cost of bioethanol production.

The researchers studied the difference in enzyme activity of free and entrapped lignocellulolytic enzymes (cellulase, xylanase and laccase) at operating conditions of 37^oC and pH 5.5. They found that the activity for entrapped enzymes increased by an average of 57.92%, 19.39% and 20.34% for cellulase, xylanase and lactase, respectively, compared to the free enzymes.This translated to an increase in monosaccharide production by 29% or from 465.46mg/g rice straw to 601.05mg/g rice straw.

From the results of this study, enzyme entrapment, according to the researchers, is a practical way to improve the biocatalytic properties (such as activity, stability and reusability) of enzymes used for the hydrolysis of rice straw and to separate the products from the reaction medium.

The full paper is published in the journal, BioresourceTechnology (URL above).