Kinetic studies on a highly productive strain of Zymomonas mobilis

Kinetic and Nuclear Magnetic Resonance Studies of Xylose Metabolism by Recombinant Zymomonas mobilis ZM4(pZB5)

“…The reductions in rates and yields from xylose metabolism were considered in the present investigation and may be due to a number of factors, including the following: (i) the increased metabolic burden from maintenance of plasmid-related functions, (ii) the production of by-products identified as xylitol, acetate, lactate, acetoin, and dihydroxyacetone by 13 Cnuclear magnetic resonance (NMR) spectroscopy and high-performance liquid chromatography, (iii) growth inhibition due to xylitol by the putative inhibitory compound xylitol phosphate, and (iv) the less energized state of ZM4(pZB5). In vivo 31 P-NMR studies have established that the levels of NTP and UDP sugars on xylose were less than those on glucose, and this energy limitation is likely to restrict the growth of the recombinant strain on xylose media.Zymomonas mobilis has attracted widespread interest for fuel ethanol production because of its higher specific rates of sugar uptake and ethanol production, higher ethanol tolerance, and higher ethanol conversion efficiencies when compared to the traditionally used yeasts (10,14,21,22,26). However, wild-type strains of Z. mobilis can only utilize glucose, fructose, and sucrose, and they lack the pentose metabolism pathway necessary to ferment such sugars as xylose or arabinose.…”

“…Zymomonas mobilis has attracted widespread interest for fuel ethanol production because of its higher specific rates of sugar uptake and ethanol production, higher ethanol tolerance, and higher ethanol conversion efficiencies when compared to the traditionally used yeasts (10,14,21,22,26). However, wild-type strains of Z. mobilis can only utilize glucose, fructose, and sucrose, and they lack the pentose metabolism pathway necessary to ferment such sugars as xylose or arabinose.…”

“…Fuels Chem., abstr. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]1999). These genetically engineered strains can now convert xylose to ethanol by the combined use of the Entner-Doudoroff and pentose pathways facilitated by the cloned enzymes xylose isomerase and xylulokinase for xylose assimilation and by transketolase and transaldolase for pentose metabolism.…”

Recombinant Cellulase and Cellulosome Systems

“…It is considered superior to brewer's yeast in other respects. Indeed, it has higher tolerance to ethanol, enabling superior yields, which it produces with high productivities [7,[49][50][51][52][53][54][55]. Therefore, several reports of recombinant cellulase expression in Z. mobilis have been published [55][56][57][58][59].…”

Using Magnetic Nanoparticles to Eliminate Oscillations in Saccharomyces cerevisiae Fermentation Processes

“…Fermentation processes involving both Saccharomyces cerevisiae and Zymomonas mobilis have been shown to exhibit oscillatory behavior [5][6][7][8][9][10][11]. The oscillatory behavior was linked to the combination of substrate excess and product inhibitions by reference [8] while reference [10] conclude that the oscillations take place at high values of feed substrate concentrations.…”