The natural degradation of plant cell wall matter in Nature is a key step in the Carbon cycle on Earth. Lignocellulose is considered the most viable option as a renewable energy source that contributes zero net emission of carbon dioxide. The main difficulty in using cellulose as an energy source is its crystalline nature, which is highly resistance to hydrolysis. Our laboratory is trying to reveal and understand how enzymes and microbial systems breakdown the plant cell wall matter and how can these systems be utilized for biotechnological applications. For example, developing an economic process for generating biofuel from cellulose. Our main research systems include the cellulosome complex from C. thermocellum and the hemicellulolytic system of G. stearothermophilus. We utilize an integrated research approach combining biochemistry, X-ray crystallography, genetic engineering, gene-regulation, microbial physiology and fermentation technology. Studies from our laboratory revealed novel regulatory mechanisms, new crystal structures and the catalytic mechanisms of selected glycoside hydrolases.