Hydrolysis of lignocellulosic

Draude, K. M., Kumiawan, C. B., and Duff, S. J. B., 2001, Effect of oxygen delignification on the rate and extend of enzymatic hydrolysis of lignocellulosic material, Biores. Technol.19 113-120. 

Recent studies have proven ethanol to be an ideal liquid fuel for transportation and renewable lignocellulosic biomass to be an attractive feedstock for ethanol fuel production by fermentation (1,2). The major fermentable sugars from hydrolysis of lignocellulosic biomass, such as rice and wheat straw, sugarcane bagasse, corn stover, corn fiber, softwood, hardwood, and grasses, are D-glucose and D-xylose except that softwood... 

Hydrolysis of lignocellulose is necessary to enable its use for ethanol production. However, when lignocellulosic materials are hydrolyzed with acid, compounds toxic to the yeast cells are released. The inhibitors are of three main types aldehydes, organic acids, and phenolic compounds. Among the aldehydes, furfural and hydroxymethylfurfural (HMF) are typically found in high concentrations—particularly in dilute-acid hydrolysates (1,2). These compounds have been shown to inhibit certain enzymes in the catabolism necessary for cell growth (3-9). 

The enzymatic hydrolysis of soluble birchwood xylan was carried out as follows The substrate (0.5 g) was placed universal or phosphate buffer in 500 mL conical flasks, and 1500 U of crude xylanase was added to start the reaction, for a total volume of 25 mL. The hydrolysis and control reactions were accomplished at the same conditions described for enzymatic hydrolysis of lignocellulosic materials. 

Kinetics of Glucose Decomposition During Dilute-Acid Hydrolysis of Lignocellulosic Biomass... 

Harvest the cellulase-containing transgenic plants at the end of the season (dry), grind this material to release enzyme, and subsequently use it in the enzymatic hydrolysis of lignocellulosic biomass for ethanol production. 

The CHAP process is based on the hydrolysis of lignocellulosic material by concentrated hydrochloric acid at low temperature and subsequent sugar fermentation. 

Pre-treatment and hydrolysis of lignocellulose releases hexoses and pentoses that are efficiently, nevertheless individually, fermented to ethanol by... 

Eriksson, T., Borjesson, J., and Tjerneld, F. 2002. Mechanism of surfactant effect in enzymatic hydrolysis of lignocellulose. Enz. Microbial Technol., 31, 353-364. 

Sun, Y. and Cheng, J. 2002. Hydrolysis of lignocellulosic material from ethanol production A review. Bioresource Technology, 83 1-11. 

The next phase in the development of advanced fermentation ethanol processes concerns the conversion to ethanol of all the pentose and hexose sugars released on hydrolysis of lignocellulosics. Traditional bakers yeast strains promote fermentation of hexoses at high yields, but over long periods of time, and they do not ferment the pentoses. Although some yeasts use both hexose and pentose sugars as sources of carbon and energy and ferment hexoses and xylose, they do not ferment arabinose and the other pentoses. The overall stoichiometry of hemicellulose hydrolysis and pentose fermentation is... 

In conclusion, enzyme preparations have been assayed for their activities and certain preparations have been identified as being most suitable for use in hydrolysis experiments. A lack of detailed knowledge about the nature of the substrate after pretreatment (porosity, size, insolubility, and crystallinity of the macroseopic particles) required us to follow an empirical approach in this study. Furthermore, the role of each enzyme in the crude enzyme preparations is difficult to assess but fundamental studies have pointed to each enzyme as having a complementary role in the sequential hydrolysis of lignocellulose [9]. The boost in... 

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