Zymomonas mobilis

TABLE 7.1 Ethanol Production by Zymomonas mobilis and Saccharomyces carlsbergensis 

Source Adapted from Rogers et al. (1982) and data from Yanase laboratory. 

Xylose catabolic genes xylA f xylB -oc tal [j iicM 1- 

Arabincse catabclic genes araB hTara/l H araP talB fj tktA h 

FIGURE 7.6 Time courses of 25-mL-scale continuous fermentation packed with the engineered Zm. mobilis using 9 1 acid hydrolysate medium at 30°C and pH 6.0 with a dilution rate of 0.25/h. After 48 hours of continuous feeding of 9 1 acid hydrolysate medium at a dilution rate of 0.01/h, feeding of 9 1 acid hydrolysate medium at a dilution rate of 0.25/h was started. Closed sqnares indicate the accumnlation of ethanol, closed diamonds the residual glucose, closed triangles the residual mannose, and closed circles the residual xylose. From Yanase etal. (2012). 

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The formation of optically active acyloins is also catalyzed by the yeast Candida Pareri if the bacteria Zymomonas mobilis and Zymomonas carlbergensis42 and the fungus Diplodia gossypina43. The latter microorganism produces (3/ ,66 )-6-hydroxy-7-oxo-8-norcitronellene from (/ )-citronellene by a reaction sequence that converts (7d)-citronellene to (/ )-4-methyl-5-butenal followed by addition of the acetyl moiety to the / e-face of the aldehyde. 

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. 

Jung, H.C., Lebeault, J.M. and Pan, J.G. (1998) Surface display of Zymomonas mobilis levansucrase by using the ice-nucleation protein of Pseudomonas syringae. Nature Biotechnology, 16, 576-580. 

Use of bioflocs rather than supported film particles will maximize the effectiveness factor for a given particle, but uneven growth of floes can cause severe stratification in the bed. If stratification can be overcome by methods such as the use of a tapered bed to control porosity the removal, breaking up, and recycle of biomass at the bottom of the bed or, ideally, the use of microbial strains or species that will stop growing at a desirable floe size, such as a Zymomonas mobilis strain that stops growing at one millimeter in diameter (Scott, 1983), the use of bioflocs rather than support particles can improve reactor productivity. 

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, D., Aivasidis, A., and Wandrey, C., Ethanolfermentation of Sugar Containing Wastes with Zymomonas mobilis in a Fluidized Bed Reactor, DECHEMA Biotechnol. Con/., 3 507 (1989)... 

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)... 

K. B. Song, J. W. Seo, and S. K. Rhee, Transcriptional analysis of levU operon encoding saccharolytic enzymes and two apparent genes involved in amino acid biosynthesis in Zymomonas mobilis, Gene, 232 (1999) 107-114. 

Secondary active uniport systems facilitating the permeation of a single solute, dependent on the electrochemical potentials of the solute molecules, are rare in bacteria. Only a glucose uptake system of Zymomonas mobilis has been studied in more detail [101]. 

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. 

Different simple correlations between biomass and fluorescence data showed that on-line estimation is possible under strictly defined culture conditions. Even a strictly finear relation between biomass and culture fluorescence was found for the growth of Zymomonas mobilis, Methylomonas mucosa, and Pseudomonas putida under non-limited conditions [47]. 

PPD from another bacterium was characterized by the Dunaway-Mariano group [26], Based on the PDC structure from Zymomonas mobilis and other ThDP enzymes [27], a hypothetical model for PPD was built. This model was then corroborated by site-directed mutagenesis of all the amino acid residues at the ThDP and phosphonopyruvate binding sites [25]. A hypothetical working model for the PPD active site is given in Fig. 2.2.2.2. 

Fig. 2.2.2.2 Postulated model of the active site of phosphonopyruvate decarboxylase. PPD from Str. viridochromogenes T0494 (based on the structure of PDC from Zymomonas mobilis [27] and data from analyis of site-directed mutants [25]). The model depicts the start of the catalytic reaction (deprotonation of the reactive C2 atom (yellow) on the thiazolium ring ofThDP...

Pawluk, A. Scopes, R.K. Griffiths-Smith, K. Isolation and properties of the glycolytic enzymes from Zymomonas mobilis. The five enzymes from gly-ceraldehyde-3-phosphate dehydrogenase through to pyruvate kinase. Biochem. J., 238, 275-281 (1986)... 

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. 

Preziosi, L, Michel, G. P. F, and Baratti, J. (1990) Characterisation of sucrose hydrolising enzymes of Zymomonas mobilis Arch Microbiol. 153, 181-186. 

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

Fig. 5.21. The end-products (circled) of microbial fermentations of pyruvate. Letters indicate the organisms able to perform these reactions. (/<) Lactic acid bacteria (Streptococcus, Lactobacillus) (B) Clostridium propionicum (C) Yeast, Zymomonas mobilis, Sarcina ventriculr, (D) Enterobacteriaceae (Coli-aerogenes) (E) Clostridia, ...

RA Moreau, MJ Powell, SF Osman, BD Whitaker, WF Fett, L Roth, DJ O Brien. Analysis of intact hopanoids and other lipids from the bacterium Zymomonas mobilis by high performance liquid chromatography. Anal Biochem 224 293-301, 1995. 

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. 

We have used a model for anaerobic fermentation in this section to simulate the oscillatory behavior of an experimental fermentor. Both the steady state and the dynamic behavior of the fermentor with Zymomonas mobilis were investigated. The four ODE model simulates the fermentor quite well. Further studies have shown that this model is suitable for scaling-up and for the design of commercial fermentors. Our model has shown the rich static and dynamic bifurcation characteristics of the system, as well as its chaotic ones. All these characteristics have been confirmed experimentally and the oscillatory/chaotic fermentor model is highly suitable for design, optimization and control purposes. 

H. Bruhn, M. Pohl, J. Groetzinger, and M.-R. Kuia, The replacement of Trp392 by alanine influences the decarboxylase/ carboligase activity and stability of pyruvate decarboxylase from Zymomonas mobilis,... 

Optimization of a continuous enzymic reaction yielding (R)-phenylacetylcarbinol (PAC), an L-ephedrine intermediate (Chapter 7, Section 7.5.2), from acetaldehyde and benzaldehyde with PDC from Zymomonas mobilis demonstrated that... 

G. Goetz, P. Iwan, B. Hauer, M. Breuer, and M. Pohl, Continuous production of (i )-phenylacetylcarbinol in an enzyme membrane reactor using a potent mutant of pyruvate decarboxylase from Zymomonas mobilis, Biotechnol. Bioeng. 2001, 74, 317-325. 

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