Conventional cell-based cellulase expression methods are time and labor intensive. Previous efforts to express cellulases in E. coli or yeast have often failed to produce active forms. A cell-free protein expression system, on the other hand, can be used as an alternative protein expression tool to address these problems. We have developed a high-throughput cellulase expression and screening platform to generate libraries of four thermophilic archaeal endocellulases, with the aim of improving their properties for industrial application. In addition, carbohydrate binding module (CBM) domains from bacterial cellulases are being added to the archaeal enzymes. The generation of  CBM fusions is directed toward improving the catalytic activity of the extremely thermophilic archaeal cellulases toward crystalline substrates.

 Finally, successful implementation of directed evolution to improve cellulase activity depends on the screening method used in enzyme selection. The poor correlation between cellulase activity on soluble and insoluble cellulosic substrates requires high-throughput methods for screening cellulase activity on relevant insoluble substrates. Our protein engineering efforts have thus employed high-throughput assays that are compatible with insoluble cellulosic substrates and constraints imposed by directed evolution strategies.