Strain improvement for degradation of lignocellulosic compounds

Lignocellulose is composed of cellulose, hemicellulose and lignin. Cellulose and hemicellulose are macromolecules of various sugars, while lignin is an aromatic polymer that made of phenylpropanoid precursors. Although cellulose, the main component of lignocellulose, is sensitive to biological degradation, but this polysaccharide is usually physicochemically bound to lignin in nature. Lignin is resistance to biodegradation and can protect cellulose against microbial attack. Lignocellulose degradation is important because has many applications in different industrial process and is used as raw material for production of the variety of biological products in different industries. Those strains employed in lignocellulose biodegradation, must have a strong and efficient enzymes in order to degrade these compounds. Some fungal strains belonging to white rot fungi are known as efficient microorganisms for degradation of lignocellulosic compounds. However, extensive researches have been carried out to improve bacterial and fungal strains for degradation of lignocellulosic compounds. In addition to the old and traditional methods such as mutagenesis, new strain improvement methods based on genetic modification have been proposed in order to increase the productivity of industrial processes. In this article, these kinds of methods have been explained in brief and some examples have been presented to show their applications for improvement of those strains are capable of degrading lignocellulosic compounds.