Saccharomyces cerevisiae bioethanol production

Smith, P.G., Beers, P.J. and Hayes, W.A., Production of bioethanol in gas-solid fluidised bed fermentation using Saccharomyces cerevisiae. Third International Conference on Environmental Impact Assessment, Prague, 1996, 453-457. 

Razmovski R. and Vucurovic V. Bioethanol production from sugar beet molasses and thick juice using Saccharomyces cerevisiae immobilized on maize stem ground tissue. Fuel 92 (1) (2012) 1-8. 

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. 

De Bari I., De Canio R, Cuna D., Liuzzi R, Capece A. and Romano P. Bioethanol production from mixed sugars by Scheffersomyces stipitis free and immobilized cells, and co-cultures with Saccharomyces cerevisiae. New Biotechnology 30 (6) (2013) 591-597. 

Yeast was the first microbial host used by mankind for biotransformation of raw materials, and it marked the early developments of industrial biotechnology. Initially, Saccharomyces cerevisiae and closely related species were used because of their high fermentative capacity and based on the vast experience from alcoholic beverage production. While a high fermentation rate is favorable for the production of bioethanol and other primary metabolites, it implicates disadvantages for growth-coupled production. Consequently, a number of other yeasts have been developed for the production of biofuels, biochemicals, lipids, or recombinant proteins. 

Saccharomyces cerevisiae is the dominant microorganism in the first generation of fuel ethanol production. In recent years, the worldwide bioethanol production reached around 80 billion liters per year. In a typical industrial scale bioethanol fermentation process using Saccharomyces cerevisiae, around 8-14% (v/v) ethanol is produced and the glucose to bioethanol yield is usually over 90% of the theoretical yield. In some processes, simultaneous saccharification and fermentation is applied, in which a-amylase/glucoa-mylase is mixed with Saccharomyces cerevisiae and starchy raw materials. Most of yeast cells harvested in the fermentation are recycled and sent back in order to enhance the cell concentration in the fermenter. Around 5-10% yeast cells end up in Dried Distillers Grains with Solubles (DDGS), which could be sold as animal feed. 

The fermentation of the sugars to bioethanol is generally performed anaerobically using commercial yeasts such as Saccharomyces cerevisiae. Heat, CO2 and a beer solution (fermentation broth) containing around 8-14% ethanol are the products of the fermentation process. The general equation for the fermentation reaction is shown below. The theoretical yield of bioethanol from this reaction is O.Slg per g of the consumed sugars while the actual yield obtained is around 90-95% of the theoretical yield. 

Other types of fermenters have been developed for specific applications. Anaerobic bioreactors are used when microorganisms do the conversions in the absence of oxygen. Examples are the acetone-butanol-ethanol (ABE) fermentation with Clostridium species, the production of lactic acid with lactic acid bacteria, and bioethanol fermentation with Saccharomyces cerevisiae. Because of the need for large volumes with these low-cost products, and the ease of construction, these... 

R, and McBride, J.E. (2007) Consolidated bioprocessing for bioethanol production using Saccharomyces cerevisiae. Adv. Biochem. Eng./Biotechnd., 108, 205-235. 

A major part of today s biofuel generation consists of the production of bioethanol through fermentation of sugars with yeast Saccharomyces cerevisiae. This is perhaps the oldest bioprocess utilised by humans. 

Gibreel A, Sandercock JR, Lan J, et al. 2009. Fermentation of Barley by Using Saccharomyces Cerevisiae Examination of Barley as a Feedstock for Bioethanol Production and Value-Added Products. Appl. Environ. Microbiol. 75(5) 1363-1372. 

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