Bioethanol production efficiencies

The compactness and complexity of (ligno)cellulose makes it much more difficult to attack by enzymes with respect to starch. Therefore, the cost of bioethanol production is higher [23], To be cost competitive with grain-derived ethanol, the enzymes used for biomass hydrolysis must become more efficient and far less expensive. In addition, the presence of non-glucose sugars in the feedstock complicates the fermentation process, because conversion of pentose sugars into ethanol is less efficient than conversion of the hexose sugars. 

The expansion of the market, however, will depend considerably on the possibility of an efficient use of other biomass sources, particularly lignocellulosic-based materials, fast growing dedicated crops, and waste resources. Effective integration of bioethanol production into biorefineries will also be a key aspect in decreasing the price by a better use of all the components of biomass. 

Compared flux profiles of recombinant strains for efficient xylose uptake Bioethanol production [361]... 

The cost of enzyme preparations has been decreasing in recent years however, it continues to affect considerably the price of ethanol obtained from cellulosic raw materials. Increased enzymatic hydrolysis efficiency is one way to reduce the enz)me cost in bioethanol production. Another method is enzyme recycle and reuse. Immobilization of biocatalysts allows for their economic reuse and development of continuous bioprocess. Although immobilization poses problems of substrate accessibility and binding for most endo- and exocellulases, P-glucosidase exhibits characteristics amenable to immobilization, such as activity on soluble substrates and the lack of a carbohydrate-binding module. Among the possible approaches, immobilization of (J-glucosidase is one prospective solution to the problem. 

Dhabhai R., Chamasia S.R and Dalai A.K. Efficient bioethanol production from glucose-xylose mixtures using co-culture of Saccharomyces cerevisiae immobilized on Canadian pine wood chips and free Pichia stipitis. Journal of Biobased Materials and Bioenergy 6 (5) (2012) 594-600. 

Alvira P, Tomas-Pejo E, Ballesteros M, Negro MJ. (2010). Pretreatment technologies for an efficient bioethanol production process based on enzymatic hydrolysis a review. Bioresour Technol, 101,4851 861. 

Galbe M, Zacchi G. (2007). Pretreatment of lignocellulosic materials for efficient bioethanol production. Biofuels, 108, 41-65. 

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