Fermentation production of ethanol

In the group of Sirkar, the application of microporous hollow fibers in the fermentative production of ethanol, acetone-butanol-ethanol (ABE), etc. has been explored. In these systems, the role of the membrane is twofold. First, oxygen or nitrogen is supplied and the reaction products CO2 and H2 are removed. Sec-... 

In vivo, pyruvate decarboxylase [EC 4.1.1.1] catalyzes the nonoxidative decarboxylation of pyruvate to acetaldehyde and is thus a key enzyme in the fermentative production of ethanol. The most well-studied PE)Cs are obtained from baker s yeast [1477, 1482, 1483] and from Zymomonas mobilis [1484]. 

A more abundantiy produced substance is ethanol for use in alcohoHc beverages, and as a fuel, solvent, and feedstock for organic syntheses. Ethanol (qv) production from sucrose is carried out in Europe (eg, France and the Netherlands), India, Pakistan, China, and on a very large scale in Brazil, where it is used as a motor fuel. A valuable by-product of ethanol fermentation is industrial CO2 (see Carbon dioxide). 

Synthesis Ga.s, Since petroleum prices rose abmpdy in 1974, the production of ethanol from synthesis gas, a mixture of carbon monoxide and hydrogen, has received considerable attention. The use of synthesis gas as a base raw material has the same drawback as fermentation technology low yields limited by stoichiometry. 

Fermentation of sugar by Saccharomyces cerevisiae, for production of ethanol in an immobilised cell reactor (ICR), was successfully carried out to improve the performance of the... 

Use of biofilm reactors for ethanol production has been investigated to improve the economics and performance of fermentation processes.8 Immobilisation of microbial cells for fermentation has been developed to eliminate inhibition caused by high concentrations of substrate and product, also to enhance productivity and yield of ethanol. Recent work on ethanol production in an immobilised cell reactor (ICR) showed that production of ethanol using Zymomonas mobilis was doubled.9 The immobilised recombinant Z. mobilis was also successfully used with high concentrations of sugar (12%-15%).10... 

Fig. 8.6. Glucose concentration, cell density and production of ethanol in batch fermentation with initial concentration of 50 g-l 1 glucose versus time. Reprinted from Najafpour et al. (2004).18 Copyright with permission from Elsevier.

Kemppainen and Shonnard compared the production of ethanol via fermentation-based processes starting with two lignoceUulosic feedstocks virgin timber resources or recycled newsprint from an luban area. For this piupose, they coupled a software-aided simulation of the fermentation process with impact assessment software. 

Second-generation biofuel technologies make use of a much wider range of biomass feedstock (e.g., forest residues, biomass waste, wood, woodchips, grasses and short rotation crops, etc.) for the production of ethanol biofuels based on the fermentation of lignocellulosic material, while other routes include thermo-chemical processes such as biomass gasification followed by a transformation from gas to liquid (e.g., synthesis) to obtain synthetic fuels similar to diesel. The conversion processes for these routes have been available for decades, but none of them have yet reached a high scale commercial level. 

The production of ethanol from cooked rice starch (Moebus and Teuber, 1985) differs from the normal process of spraying the carbon source into the bed since all of the carbon source is made available at the start of the run, subject only to the breakdown of starch to glucose (and maltose) by amylases. The starch (0.3 mm particles), amylases and yeast pellets were mixed in the bed and water sprayed in to maintain the fermentative activity of the yeast. The fermentation was carried out at 31.5°C. 

Moebus, O. and Teuber, M., Ein neues fermentations-system Herstellung von ethanol in der wirbelschicht [A new fermentation system production of ethanol in a fluidized bed], in Dellweg, H., (ed.), 5 Symp. Technische Mikrobiologie, Berlin, 1982b, 290-297. 

Development and modelling of a gas/solid fluidized bed fermenter for the production of ethanol with S. cerevisiae. Dissertation, Technical University of Hamburg-Harburg, 1985. 

Food can be preserved by fermentation using selected strains nf yeast, lactic acid-producing bacteria, or molds. The production of ethanol, lactic and other organic acids, and anlimicrobial agents in the food, along with the removal of fermentable sugars, can yield a product having an extended shelf life. 

In this fermentation process, sustained oscillations have been reported frequently in experimental fermentors and several mathematical models have been proposed. Our approach in this section shows the rich static and dynamic bifurcation behavior of fermentation systems by solving and analyzing the corresponding nonlinear mathematical models. The results of this section show that these oscillations can be complex leading to chaotic behavior and that the periodic and chaotic attractors of the system can be exploited for increasing the yield and productivity of ethanol. The readers are advised to investigate the system further. 

G. R. Cysewski, C.R. Wilke, Process design and economic studies of alternative fermentation methods for the production of ethanol, Biotechnology Bioengineering, 20(9), 1421-1444, 1978... 

The first-generation biofuels can be identified as ethanol, which was produced via the alcoholic fermentation of cereals, and hio-oil or biodiesel, which was extracted from seeds such as sunflower, rapeseed, or palm. The use of cereals and sunflowers was rejected by public opinion and some scientific environments, because their use for energy production conflicted with their use as foodstuffs. In fact, the diversion of cereals to the production of ethanol for transport has led to a rise in the price of flour and derived goods, especially in Mexico. The same situation has arisen for some bio-oils, such that the source was shifted to palm-oil which, essentially, is produced in Asian countries such as Malaysia. 

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