The general understanding of cellulose degradation at present is that for efficient breakdown of crystalline cellulose, three types of enzymes are needed. They are endo glucanases (EGs, which cut cellulose chains randomly), cellobiohydrolases (CBHs, which cleave cellobiose from the cellulose chain ends) and b-glucosidases (which hydrolyze cellobiose and cellodextrins into glucose). Efficient cellulose degradation by microbes is achieved in two major ways. Production of a ‘soup’ of different enzymes that can work synergistically is one method. These different enzymes could have differential expression depending on the substrate, time and other stimuli. The second method is cellulosome activity. In this approach, different enzymes are found associated as one complex (the cellulosome) for fast breakdown of cellulose.