Glucose pretreated lignocellulose

Many pretreatments have been employed to enhance the degradation of lignocellulosic materials to glucose. The treatments fall into two general areas (Ryu and Lee, 1983) ... 

Wood hydrolysis has been limited to cellulose degradation by cellulase enzymes. These en mes are typically low activity and highly inhibited by the glucose product. As mentioned above, mild acid pretreatment has been found to be an important first step in the biomass utilization process. The pretreatment is used both to break down the hemicellulose to sugars and to disrupt the lignocellulosic structure and tlie crystallinity of the cellulose. 

Supercritical CO2 is used for carbon dioxide explosion pretreatment. CO2 is cheap, nontoxic, inflammable, and easy to extract after explosion (Taherzadeh and Karimi, 2008). Due to the release of carbon dioxide at high pressure, lignocelluloses are disturbed, which increases the surface area for further hydrolysis. Glucose release was observed to increase with increasing pressure and temperature of the carbon dioxide was applied in supercritical carbon dioxide explosion. However, using subcritical carbon dioxide results in opposite scenario. 

Based on the abilities discussed above, including the simultaneous utilization of a sugar mixture comprised of glucose, xylose, arabinose, and cellobiose and tolerance toward inhibitory by-products generated during pretreatment of lignocellulosic biomass, Corynebacterium has the potential to be developed into a useful ethanologenic bacterium. 

Complete utilization of cellulose and hemicellulose requires selection or genetic modification of an organism that is able to ferment pentoses. In order to obtain monosaccharides from the raw material, several pretreatments and/or separations are required. First, the lignocellulosic material is mechanically treated and then delignified (pulped) by strong alkali or acid treatment. The (hemi)cellulose part becomes more accessible for enzymes at the same time. Subsequent enzymatic treatment mainly yields glucose and xylose and some arabinose. The enzymatic treatment and subsequent fermentation can be done in separate reactors or in one fermenter, in an SSF concept similar to starch SSF [57]. 

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