Production from starch

The production of ethanol from sugar derived from starch and sucrose has been commercially dominated by the yeast S. cerevisiae (31). However, the sugar obtained from biomass is a mixture of hexoses and pentoses. Now, most wild-t5 e strains of S. cerevisiae do not metabolize xylose (13). 

Strength has been undertaken to increase the yields of fermentation (13)  

To add additional pentose and to use genetic engineering for other ethanologens, and 

To improve the yield of ethanol by genetic engineering of microorganisms 

Even when these methods are successful, they are not ripe for commercial use. Moreover, in contrast to the clean sugar streams derived from starch and sucrose, hydrolysates derived from biomass tend to have fermentation inhibitors, such as acetic acid, or furfural. These compounds must be either removed when their concentrations are high. Or else, robust strains must be developed that are resistant to the above inhibitors. 

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Gfeller, R.P., Gibbs, M. 1984. Eermentative metabolism of Chlcmtydomonas reinhardtiV. 1. Analysis of fermentative products from starch in dark-light. Plant Physiology 75 212-218. 

Figure 1. Schematic process biochemistry of enzymatic fructose production from starch. Reprinted with permission from ref. 1. Copyright 1990 Elsevier.

Since fermentation takes place in a dilute aqueous solution, the reaction continues until the alcohol concentration approaches about 14%. At higher concentrations, the process becomes self-inhibitory. By-products from starch fermentation to ethanol can include higher-molecular-weight alcohols, glycerine, and ethers. Usually no more than 10% starch is converted to these compounds. Atmospheric distillation, vacuum distillation, and membrane separation techniques can be used to recover ethanol from the final fermented product. The distillate bottoms, called stillage, are recovered as a by-product for animal feed. A biomass fermentation flow diagram is provided in FIGURE 12-2. 

Liu, G., and Shen, J. 2004. Effects of culture and medium conditions on hydrogen production from starch using anaerobic bacteria. J. Biosci. Bioeng., 98, 251-256. 

Zhang, T., Liu, H., and Fang, H. H. P. 2003. Biohydrogen production from starch in wastewater under thermophilic condition. J. Environ. Management, 69,149-156. 

Yokoi, H., Mori, S., Hirose, J., Hayashi, S., and Takasaki, Y. 1998. Hydrogen production from starch by a mixed culture of Clostridium butyricum and Rhodobacter sp. M-l 9. Bio-technol. Lett. 20, 890-895. 

It is not easy to show that a preparation of malt a-amylase is enzy-mically homogeneous and free from /3-amylase and maltase. As will be shown later, the enzyme liberates D-glucose as a primary product from starch. Thus the appearance of D-glucose is not evidence of the presence of maltase. But the absence of this enzyme is most easily demonstrated... 

According to the well known General Dynamical Model Approach by Bastin and Dochain (1990), a model for the control of the process can be derived on the basis of a process reaction scheme. For the bio-ethanol production from starch by Saccharomyces... 

Taguchi, F., Chang, J.D., Takiguchi, S. and Morimoto, M. (1992). Efficient hydrogen production from starch by a bacterium isolated from termites. J. Ferment. Bioeng. 73, 244-245. 

The Role of the Isolated Strains in H2 Production From Starch... 

BCI produced approx. 40 mmol H2 from 1/ of the starch-containing H2 production medium. Almost the same amount of H2 was evolved by the 2-membered cocultures consisting of strains A-501 and T-522, and of strains A-501 and T-59. The other 2-membered cocultures, consisting of R. marinum A-501 and P. vulgaris T-51 or T-53 to T-58, failed to evolve H2. Thus, it was confirmed that H2 production from starch was a result of cooperation between R. marinum and V. fluvialis. 

Fumaric acid production from starch hydrolysate by R. arrhizus NRRL 1526 was studied by Federici et al. [75] in a 3-1 stirred-tank fermentor with CaCO, and KOH/KCO3 as the neutralizing agent and CO2 source. The fermentation conditions for fumaric acid production by this fungus from potato flour has been optimized by Moresi et al. [76]. 

Cyclodextrins are degradation products from starch by the bacterium Bacillus macerans. They are separated by precipitation with complexing agents and purified by recrystallization. They could probably be produced industrially by the tonne. The formation of cyclodextrins is interpreted as a trans glycosidation of amylose under enzymic control. The latter, in aqueous solution, adopts at least partially the shape of a helix with a period of six glucopyranose units. The bacterial enzyme catalyses the junction of two glucopyranose residues separated... 

Amounts of Volatile Products from Starch and Related Materials after Pyrolysis for 18 h at 300 ... 

Pyrolysis Products from Starch-like Materials. 496... 

Fig. 3.—Production from Starch of (1) Pyrolytic Residue, and (2) Total Sirup, as a Function of Temperature. Amounts expressed as the Percentage of the Original Weight. (Reproduced by permission of Die Staerke.)...

Oxidation products from starch are also available indirectly. For example, Horton and coworkers485-487 prepared 6-aldehydo amylose and starch derivatives by photolysis of 6-azido-6-deoxy derivatives. The oxidation pattern of starches can be determined by hydrolysis of the reaction product and subsequent identification of the components of such hydrolyzates as their trimethylsilyl derivatives 488... 

Altuntas E.G. and Ozcelik F. Ethanol production from starch by co-immobilized amyloglucosidase— Zymomonas mobilis cells in a continuously-stirred bioreactor. Biotechnology and Biotechnological Equipment 27 (1) (2013) 3506-3512. 

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