Search results for "ZYMOMONAS MOBILIS"
showing 10 items of 63 documents
Fructan Biosynthesis by Intra- and Extracellular Zymomonas mobilis Levansucrase after Simultaneous Production of Ethanol and Levan
2003
Summary The chemical composition of the Zymomonas mobilis biomass and the culture liquid after ethanol and levan synthesis were studied. The activities of intra- and extracellular levansucrase produced by the Z. mobilis strain 113 ”S” under optimum conditions both for levan and fructooligosaccharide (FOS) synthesis were also determined. It was shown that levan production relates to the reduction of the carbohydrate and lipid content in the biomass by increasing the nucleic acid and protein content. The levan producing activity of cellular levansucrase after ethanol and levan synthesis was approximately 30–40% of the total activity in the second fermentation stage. It was established that th…
Flame-burned stainless steel wire spheres as carriers ofZymomonas mobilis cells and extracellular levansucrase
1999
In the present work, the use of flame-burned WS as carriers of Z. mobilis and extracellular levansucrase and the effect of the cell fixation method by dehydration on system productivity were investigated. Lyophilization and convective drying of Z. mobilis biomass at 30°C to a moisture content of 10–14% gave the best results for the repeated batch fermentations of a sucrose medium to obtain levan and ethanol. Significant correlation between the product formation and the concentration of free cells in the fermentation medium was established. Clearly, the cells were weakly bound to the newly generated WS and were washed out into the medium during fermentation. Here the hypothesis is presented …
Sugar Beet Juice Fermentation byZymomonas mobilis Attached to Stainless Steel Wire Spheres
2001
The fermentation of sugar beet juice as well as juice syrup medium by Zymomonas mobilis inoculum attached to stainless steel wire spheres was investigated. A semi-synthetic sucrose medium enriched with mineral salts and yeast extract was used as the control. It was established that raw sugar beet juice ensured good Zymomonas mobilis culture growth and slightly decreased ethanol synthesis applying both flame-burned and TiCl 4 -treated wire spheres as carriers (Q x = 0.05-0.06 g/l × h: Q eth = 1.02-1.22 g/l × h). High ethanol yield was also observed in juice medium (Y = 0.45-0.46 g/g), however, levan synthesis with this medium decreased. The application of juice syrup brought about less growt…
Sucrose medium osmolality as a regulator of anabolic and catabolic parameters inZymomonas culture
1996
This study focuses on the growth of Zymomonas mobilis strain 113 S and its ethanol and levan production under the conditions of increasing sucrose medium osmolality caused by NaCl, KCl, sorbitol or maltose. The increase in medium osmolality (700-1,500 mosml/kg) was accompanied by the inhibition of growth (growth rate, biomass yield) and ethanol production (specific productivity and yield). In contrast, levan synthesis was less affected or even stimulated and, as a consequence, levan specific productivity was increased significantly. A decrease in the anabolic growth parameters correlated with a parallel inhibition of glucose-6-P dehydrogenase and alcohol dehydrogenase (isoenzyme ADH II) act…
The effect of mixing on glucose fermentation by Zymomonas mobilis continuous culture
2003
Abstract The influence of mixing (in the range from 300 to 1100 rpm) on the performance of Zymomonas mobilis anaerobic continuous culture was studied. Biomass yield and ethanol productivity were improved at higher stirring intensities, in parallel with a decrease in byproduct synthesis. A mixing-dependent formation of minor amounts of fructose was first demonstrated in Z. mobilis anaerobic culture on glucose. The rate of fructose synthesis and the specific activity of the key enzyme in the pathway to fructose, phosphoglucose isomerase (EC 5.3.1.9), had a maximum at 700 rpm.
Hydrophobicity of bacteria Zymomonas mobilis under varied environmental conditions
2007
Abstract Changes in the cell surface hydrophobicity (CSH) of bacteria Zymomonas mobilis 113S were examined in response to varied environmental conditions (temperature and phase of growth, concentration or type of carbon source, the presence of amphiphilic compounds). The values of CSH were elevated with a decreased growth rate over the time of cultivation up to 20–22% at the stationary phase. CSH values increased proportionally with the growth of cultivation temperature and concentration of carbon source (glucose or sucrose) or amphiphilic compound (aliphatic alcohols, Tween80) in the medium. Replacement of sucrose by glucose and the presence of Tween20 in the growth medium resulted in redu…
Respiratory behaviour of a Zymomonas mobilis adhB::kan(r) mutant supports the hypothesis of two alcohol dehydrogenase isoenzymes catalysing opposite …
2006
AbstractPerturbation of the aerobic steady-state in a chemostat culture of the ethanol-producing bacterium Zymomonas mobilis with a small pulse of ethanol causes a burst of ethanol oxidation, although the reactant ratio of the alcohol dehydrogenase (ADH) reaction ([NADH][acetaldehyde][H+])/([ethanol][NAD+]) remains above the Keq value. Simultaneous catalysis of ethanol synthesis and oxidation by the two ADH isoenzymes, residing in different redox microenvironments, has been proposed previously. In the present study, this hypothesis is verified by construction of an ADH-deficient strain and by demonstration that it lacks the oxidative burst in response to perturbation of its aerobic steady-s…
Kultivācijas apstākļu ietekme uz etanolveidojošo un pienskābes baktēriju virsmas īpašībām un fizioloģisko noturību
2013
Elektroniskā versija nesatur pielikumus
The Low Energy-Coupling Respiration in Zymomonas mobilis Accelerates Flux in the Entner-Doudoroff Pathway.
2015
Performing oxidative phosphorylation is the primary role of respiratory chain both in bacteria and eukaryotes. Yet, the branched respiratory chains of prokaryotes contain alternative, low energy-coupling electron pathways, which serve for functions other than oxidative ATP generation (like those of respiratory protection, adaptation to low-oxygen media, redox balancing, etc.), some of which are still poorly understood. We here demonstrate that withdrawal of reducing equivalents by the energetically uncoupled respiratory chain of the bacterium Zymomonas mobilis accelerates its fermentative catabolism, increasing the glucose consumption rate. This is in contrast to what has been observed in o…
Zymomonas mobilis metabolism: Novel tools and targets for its rational engineering
2020
Abstract Zymomonas mobilis is an α-proteobacterium that interests the biofuel industry due to its perfect ethanol fermentation yields. From its first description as a bacterial isolate in fermented alcoholic beverages to date, Z. mobilis has been rigorously studied in directions basic and applied. The Z. mobilis powerful Entner-Doudoroff glycolytic pathway has been the center of rigorous biochemical studies and, aside from ethanol, it has attracted interest in terms of high-added-value chemical manufacturing. Energetic balances and the effects of respiration have been explored in fundamental directions as also in applications pursuing strain enhancement and the utilization of alternative ca…