Hydrolysis bioethanol production

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 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. 

The results presented in this paper were only a very preliminary study of pretreatment of maize silage. Trials should be made at lower temperatures to examine if more energy could be saved in the process. It would also be interesting to determine the content of starch and cellulose separately by enzymatic hydrolysis, instead of total glucan as is the case in this study. Also, enzymatic hydrolysis and SSF using low enzyme loadings (of both cellulases and amylases) should be made to fully see the potential of this promising raw material for bioethanol production. 

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. 

Chaudhary G, Singh LK, Ghosh S. (2012). AlkaUne pretreatment methods followed by acid hydrolysis of saccharum spontaneum for bioethanol production. Bioresour Technol, 124, 111-118. 

The search for new and cheap substrates for the production of bioenergy and other biotechnological products is continuously demanded. Pal et al. reported that the mustard stalk and straw served as an alternative substrate for the production of lignocellulolytic enzymes and as a source for saccharification. The biomass from halophyte plants such as Retama retam and Juncus maritimus were used as the substrate for bioethanol production. The combined effect of thermochemical pretreatment and enzymatic hydrolysis of kitchen wastes for maximizing the production of fermentable soluble sugars has been described previously. ... 

Samsuri, M., M. Gozan, B. Prasetya, and M. Nasikin. 2009. Enzymatic Hydrolysis of Lignocellulosic Bagasse for Bioethanol Production. Journal of Biotechnology Reseaech in Tropical Region 2 (2) l-5. 

Ethanol production by F. oxysporim F3 was considerably affected by pH of both aerated and non-aerated cultures [64], Optimum values were obtained when the pH of the aerated and non-aerated culture of cellulose were 5.5 and 6.0, respectively. It could be due to the changes induced by low pH to systems involved in cellulose hydrolysis, utilization of sugars for bioethanol production, or both [64], At optimum pH, no insoluble cellulose could be detected in the culture medium. On the other hand, low pH of the aerated culture resulted in low ethanol yield. Adjustment of the initial pH in non-aerated growth to an optimal pH was established to be optimal for both P-glucosidase activity and ethanol production, as a consequence the conversion time resulted to about half [65],... 

Jain S, Lala AK, Bhatia SK, Kudchadker AP (1992) Modeling of hydrolysis controlled anaerobic-digestion. J Chem Technol Biotechnol 53 337—344 Jeon YJ, Xun Z, Rogers PL (2010) Comparative equations of cellulosic raw materials for second generation bioethanol production. Lett Appl Microbiol... 

Hsu,C. L, Chang, K. S.,Lai,M. Z, Chang, T. C., Chang, Y.H., Jang, H.D.Pietreatment and hydrolysis of cellulosic agricultural wastes with a cellulase-producing Streptomyces for bioethanol production. Biomass and Bioenergy 2011, 35,1878-1884. 

Martin, M., Grossmann, I.E. (2012). Energy optimization of bioethanol production via hydrolysis of switchgrass, AIChE Journal, 58,1538-1549. 

Morales-Rodriguez, R., A. S. Meyer, K. V. Gemaey and G. Sin (2011b). Dynamic model-based evaluation of process configurations for integrated operation of hydrolysis and co-fermentation for bioethanol production from lignocellulose. Bioresource Technology 102(2) 1174-1184. 

Harun, R. Danquah, M. K. Enzymatic hydrolysis of microalgal biomass for bioethanol production. Chem. Eng. J. 2011a, 168, 1079-1084. 

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