Zymomonas mobilis, ethanol

Owing to diminishing fossil fuel reserves, alternative energy sources need to be renewable, sustainable, efficient, cost-effective, convenient and safe.1 In recent decades, microbial production of ethanol has been considered as an alternative fuel for the future because fossil fuels are depleting. Several microorganisms, including Clostridium sp. and yeast, the well-known ethanol producers Saccharomyces cerevisiae and Zymomonas mobilis, are suitable candidates to produce ethanol.2,3... 

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... 

Gunasekaran, P. and Raj, K.C., 2001. Ethanol fermentation technology - Zymomonas mobilis, httn //ces.iisc.ernet.in/curscinew/iulvl0/articlesl4.htm. 

There are two popular microorganisms that can produce high concentrations of alcohol. Their tolerance to high concentrations of ethanol and substrates are stated in the literature.3-5 The most common are Zymomonas mobilis and Saccharomyces cerevisiae. 

Strohhacker J, AA de Graaf, SM Schoberth, RM Wittig, H Sahm (1993) P nuclear magnetic resonance studies of ethanol inhibition in Zymomonas mobilis. Arch Microbiol 159 484 90. 

Scott, C. D., Ethanol Production in a Fluidized-Bed Bioreactor Utilizing Flocculating Zymomonas Mobilis with Biomass Recycle, Biotechnol. Bioeng. Symp. Ser., 13 287 (1983)... 

Weuster-Botz, D., Continuous Ethanol Production by Zymomonas mobilis in a Fluidized Bed Reactor. Part I. Kinetic Studies of Immobilization in Macroporous Glass Beads, Appl. Microbiol. Biotechnol., 39 679 (1993)... 

Recently, Edye et al, (4) described a fermentation process which used a mutant strain of Zymomonas mobilis to produce high concentrations of fructose and ethanol when grown on a concentrated sucrose medium. Johns and Greenfield (5) proposed ethanolIc crystallization as a means of recovering the fructose from the broth. The kinetic behaviour of fructose crystallization from ethanolIc solution has not been previously reported, and this work Investigates these crystallization kinetics. 

Some lactic acid bacteria of the genus Lactobacillus, as well as Leuconostoc mesenteroides and Zymomonas mobilis, carry out the heterolactic fermentation (Eq. 17-33) which is based on the reactions of the pentose phosphate pathway. These organisms lack aldolase, the key enzyme necessary for cleavage of fructose 1,6-bisphosphate to the triose phosphates. Glucose is converted to ribulose 5-P using the oxidative reactions of the pentose phosphate pathway. The ribulose-phosphate is cleaved by phosphoketolase (Eq. 14-23) to acetyl-phosphate and glyceraldehyde 3-phosphate, which are converted to ethanol and lactate, respectively. The overall yield is only one ATP per glucose fermented. 

Ethanol Saccharomyces cerevisiae, Zymomonas mobilis, Clostridium thermocellum and other Clostridium spp. Alcoholic beverages solvent in chemical industry fuel extender... 

The parameters of this model offer a physiologically adequate description of the growth and fermentation of Zymomonas mobilis. Furthermore, this model is highly consistent with experimental fermentor data. Specifically, it predicts the response of the steady state RNA content of the biomass to elevated ethanol concentrations qualitatively. The effect of an elevated ethanol concentration on the fermentation kinetics resembles the effect of elevating the temperature of the fermentation broth. 

Kim, C.H. and Rhee, S.K., Ethanol production from Jerusalem artichoke by inulinase and Zymomonas mobilis, Appl. Biochem. Biotechnol., 23, 171-180, 1990. 

Allias, J.-J., Favela-Torres, E., and Baratti, J., Continuous production of ethanol with Zymomonas mobilis growing on Jerusalem artichoke juice, Biotechnol. Bioeng., 29, 778-782, 1987. 

Toran-Diaz, I., Delezon, C., and Buratti, J., The kinetics of ethanol production by Zymomonas mobilis on fructose medium, Biotechnol. Lett., 5, 409 -12, 1983. 

Gold, R. S., Meagher, M. M., Tong, S., Hutkins, R. W., and Conway, T. 1996. Cloning and expression of the Zymomonas mobilis production of ethanol genes in Lactobacillus casei. Curr. Microbiol., 33,256-260. 

Nichols, N. N., Dien, B. S., and Bothast, R. J. 2003. Engineering lactic acid bacteria with pyruvate decarboxylase and alcohol dehydrogenase genes for ethanol production from Zymomonas mobilis. J. Ind. Microbiol. Biotechnol., 30, 315-321. 

Zhang, M., Eddy, C., Deanda, K., Franden, M. A., Finkelstein, M., and Picataggio, S., Metabolic engineering of zymomonas-mobilis for ethanol-production from renewable feedstocks. Abstracts of Papers of the American Chemical Society 1995, 209, 115-BTEC. 

Alcoholic fermentation is the anaerobic transformation of sugars, mainly glucose and fructose, into ethanol and carbon dioxide. This process, which is carried out by yeast and also by some bacteria such as Zymomonas mobilis, can be summarised by this overall reaction. 

Flesch, G., and Rohmer, M. (1989). Prokaryotic triterpenoids. A novel hopanoid from the ethanol-producing bacterium Zymomonas mobilis. Biochem J 262 673-675. 

Ethanol Various sugars Kluyveromyces sp. Candida utilis Saccharomyces cerevisiae Zymomonas mobilis... 

Metabolic engineering [39, 40] has been used to impart the capacity for ethanol production and xylose fermentation in E. coli [41-45], Klebsiella oxytoca [A6,A7],Zymomonas mobilis [48,49] andS. cerevisiae [50-53]. In general, attempts at metabolic engineering have been more successful in bacteria than in yeasts. Although the reasons are not entirely clear, the smaller genomes and fewer feedback regulatory factors found in bacteria make these organisms much easier to work with. 

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