Salom Gnana Thanga, Nagamani Balagurusamy* and K. Ramasamy*
In: Biocatalysts in biomass to bioproducts (Eds.) K. Ramasamy, S. Karthikeyan and U. Sivakumar. Daya Publishing House, New Delhi, India. pp. 91-100. (ISBN: 978-93-5124-831-6 & 978-93-86071-69-9).
Lignocellulosic biomass is one of the abundantly available raw materials, which by means of biotechnological processes can be converted to value added products. Although delignification is a rate limiting step, biological conversion of cellulosic biomass to fuels, chemicals and other value added products at low cost and by using environmental friendly technologies is feasible. Nevertheless, many microorganisms in nature, mostly bacteria and fungi are capable of producing biomass-degrading enzymes (Yang et al. 2011). Enzymatic hydrolysis is influenced by both structural features of cellulose and the mode of enzyme action. Two types of systems occur in regard to plant cell wall degradation by microorganisms. In one type, the organisms produce a set of free enzymes that act synergistically to degrade plant cell walls. In the second type, the degradative enzymes are organized into an enzyme complex located in cellular surface called the cellulosome. This complex is very effective in degrading plant cell walls (Doi, 2008). The occurrence of a cellulosome was first observed in the thermophilic bacterium Clostridium thermocellum and has been described in a number of mesophilic anaerobic bacteria and with some anaerobic fungi, particularly Piromyces sp. (Doi 2008; Lamed et al.1987). This paper focuses on the current understanding of key features of cellulosome and its role in biomass hydrolysis.