Lytic Polysaccharide MonoOxygenases; their role for lignocellulose depolymerization and production of (functional) biobased compounds

Abstract: Increased environmental concerns over petroleum based products triggered a need to find a sustainable alternative for fuels, chemicals etc. Lignocellulose biomass, due to its abundance, is considered as one of the most potential and sustainable sources for the production of value added chemicals and fuels while replacing the traditional petroleum resources. In a bio-refinery, with the help of a greener bio-chemical conversion using enzymes, cellulose in the biomass is broken down into monomeric sugars which can be later converted into fuels or chemicals. This process is done with the help of different cellulose digesting enzymes (cellulases), isolated from wood degrading fungi found in nature.Lytic Polysaccharide MonoOxygenases is one of the essential group of enzymes in the bio-conversion of lignocellulose. They are copper active enzymes present in the cellulose degrading fungi in nature. They are different from the traditional cellulases with their unique way of oxidative breakage of cellulose in the presence of oxygen and a reducing agent such as lignins present in the wood. Their ability to enhance the action of traditional cellulases in the depolymerization of cellulose, make them an integral part of today’s commercial cellulose cocktails.Liquefying lignocellulose in the most efficient way, for better release of individual monomeric sugars from it, and the potential use of residual fibers for the production of value added products such as nanocellulose, by minimizing the environmental impact due to chemical process is one of important goals of biorefinery research. Lytic Polysaccharide MonoOxygenases along with other cellulases have been shown to be very beneficial in this process.This thesis comprises of the study about their action on various cellulose substrates, both model and natural. The evaluation was done based on their ability to release neutral and oxidized sugars along with the abilities of these unique enzymes to liquefy substrates. Effect of various pretreatment methods of lignocellulose in the action of LPMOs is studied, along with their capability to use lignin present in the wood as a reducing agent which gives a better understanding about their function in nature. Finally, their role in producing value added materials such as nanocellulose, compositional sugars such as glucose and cellobiose etc from lignocellulose is also evaluated.