Biotechnology hemicellulose

A very important step in the process is the simultaneous saccharification and fermentation. This requires enzymes that can effectively break the cellulosic and hemicellulosic material into sugar components. Additionally, micro-organisms that can use a wide range of sugars are desired. These are challenges to be solved by future research in the field of biotechnology. 

A third trend is towards the search for cheap feed stock sources. This development started quite a while ago. Methanol used as a carbon source for microbial growth is of real interest at present. Cellulose and hemicellulose as components of wood are not yet an economic alternative, but recent progress is very impressing. It can easily be foreseen that wood will be utilized as a new resource for biotechnology within the next 10 years. 

Hemicellulose can be used as a source of raw material for several industrial processes. This polymer is applied in the biotechnology and pharmaceutical uses by formulation of various derivatives through a variety of chemical reactions [33, 34, 40]. 

In the last decade, increasing efforts have been dedicated worldwide to realizing the implementation of biorefinery plants for the eonversion of lignocellulosic and cellulosic waste to starting materials for the biotechnological production of bioethanol, biopolymers and a range of fine chemicals. Whereas the material recovery from the lignin fraction is limited to the production of adhesives, sulphur-free fuels and some aromatics, cellulose and hemicellulose provide a rich source of... 

Nigam, J. N. (2001). Ethanol production from wheat straw hemicellulose hydrolysate by Pichia stipitis. Journal of Biotechnology, 87, 17—27. 

Biotechnology continues to be an important contributor to the biorefinery, especially for the conversion of carbohydrates. The paper by Richard describes a new approach for the fermentation of C sugars, providing methodology for more efficient conversion of biomass carbohydrates to EtOH. The contribution from Nakas discusses the bioproduction of polyhydroxyalkanoates using levulinic acid as a carbon source. Stipanovic describes new approaches for using hemicellulose as a chemical feedstock. 

The chemical process is very expensive because of the high working temperature, application of pressme for the hydrogenation of xylose, and extensive steps for separation and purification. The industrial-scale production contains less xylose and other sugars such as arabinose, maimose, galatose, and glucose as major impurities (Sakakibara et al., 2009). From the economic viewpoint, the biotechnological production of xylitol seems to be very attractive, with the use of low-cost crude hemicellulosic hydrolysate as a potential substrate (Rao et al., 2006). 

Borges, E.R., Pereira Jr., N., 2011. Succinic acid production from sugarcane bagasse hemicellulose hydrolysate by Actmct>acUlus succinogenes. Journal of Industrial Microbiology Biotechnology 38,1001-1011. 

Jacobsen, S Ji., Wyman, C.E., 1999. Hemicellulose and cellulose hydrolysis models for application to current and novel pretreatinent processes. Applied Biochemistry and Biotechnology 84—86, 81—96. 

Most biotechnological applications of hemicellulose utilize acid and/or solvent-based hydrolysates, in which the native xylan is cleaved to xylose and xylose oligomers. This saccharification can be achieved through such chemical means, but also by physical and/or enzymatic methods. Forest biomass is often treated with dilute acid or enzymatic hydrolysis as a pretreatment for fermentative application of the hemicellulosic fraction. Dilute acid hydrolysis generally uses low concentrations of mineral acids (H2SO4, HCl, 2-5%) at high temperatures (e.g. 150-170 °C) and pressures (10 atm) (Sun and Cheng, 2002). Concentrated... 

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