Concurrent production of ferulic acid and glucose from wheat bran by catalysis of a putative bifunctional enzyme

The aim of this work is to study a bifunctional endoglucanase/carboxylesterase in Sphingobacterium soilsilvae Em02 and express it in soluble form in engineered Escherichia coli. The molecular weight of the recombinant protein of the bifunctional enzyme was 41 KDa. This research also determined the enzymatic activities of the bifunctional enzymes using microcrystalline cellulose and p-nitrophenyl butyrate as substrates and found 40 degrees C as the optimum temperature for their enzymatic activities. The optimal pH in dual function was 6.0 for endo-glucanase and 7.0 for carboxylesterase. The bifunctional enzyme also exhibited enzymatic activities on the natural biomass by generating up to 3.94 mg of glucose and 49.4 mu g of ferulic acid from 20 mg of destarched wheat bran. This indicates the broad application prospects of the bifunctional enzyme in agriculture and industry.