Enzymes known as cellulases are currently used to break down cellulosic fibers but their efficiency is low and commercial cellulase cocktails are expensive. Furthermore, these cocktails lose their activity at the high temperatures and salt concentrations typically found in next generation pretreatment conditions.
We have employed a modular approach to engineer highly robust cellulases by fusing thermophillic cellulose-binding modules (CBMs) to catalytic domains. Here we demonstrate that the addition of CBMs enhances enzymatic activity compared to the catalytic domain alone at high temperatures. Furthermore, we show that linker characteristics and fusion geometry affect the catalytic rate of these chimeric enzymes when assayed on insoluble crystalline substrate Avicel and on a model energy crop, switchgrass. We discuss some of our initial results and outline a strategy directed towards improving the activity of these chimeric cellulases under high salt conditions.