Glucose and fructose metabolism in Zymomonas anaerobia

Abstract

Isotopic and enzymic evidence indicates that Zymomonas anaerobia ferments glucose via the Entner-Doudoroff pathway. The molar growth yields with glucose (5.89) and fructose (5.0) are lower than those for the related organism Zymomonacs mobilis and the observed linear growth suggests that energetically uncoupled growth occurs. A survey of enzymes of carbohydrate metabolism revealed the presence of weak phosphofructokinase and fructose 1,6-diphosphate aldolase activities but phosphoketolase, transketolase and transaldolase were not detected. Fermentation balances for glucose and fructose are reported; acetaldehyde accumulated in both fermentations, to a greater extent with fructose which also yielded glycerol and dihydroxyacetone as minor products.

Pentose metabolism in Zymomonas mobilis wild-type and recombinant strains

“…In conjunction with glucose-6-phosphate-dehydrogenase, the enzyme (GND) could also serve to generate NADPH ÷ for fatty acids biosynthesis. In contrast to the report of McGill and Dawes (1971), we were able to detect faint TKT activity in Z. mobilis, being essential for the production of erythrose 4-phosphate as a precursor for aromatic amino acids from fructose 6-phosphate and glyceraldehyde-3-phosphate.…”

“…As described by McGill and Dawes (1971), a weakly selective GND specific for NADP ÷ was detected, which functions most probably to provide pentose phosphates for nucleic acid synthesis. In conjunction with glucose-6-phosphate-dehydrogenase, the enzyme (GND) could also serve to generate NADPH ÷ for fatty acids biosynthesis.…”

Isolation of Zymomonas Mobilis From Primed Beer*

“…Such preference for sucrose is unusual, as another isolate of Z. mobilis revealed lower molar growth yields with sucrose than with glucose and fructose. 8 Presence of a sucrose-fermenting zymomonad was sought in brewery plant but both dispatching and receiving breweries were free of such an organism. It was assumed, therefore, that the source of infection was the road tanker.…”

Activities of the enzymes of the Ehrlich pathway and formation of branched-chain alcohols in Saccharomyces cerevisiae and Candida utilis grown in continuous culture on valine or ammonium as sole nitrogen source

“…Assays were all performed in 1 ml reaction volumes at 25 "C. One unit of enzyme activity is the amount required to catalyse the transformation of 1 pmol of substrate or the formation of 1 pmol of product min-*. Assays were performed according to the following methods : alcohol dehydrogenase (McGill & Dawes, 1971), pyruvate decarboxylase and citrate synthase (Clarkson et al, 1991), alkaline phosphatase (Green & Large, 1984), NAD-and NADPdependent glutamate dehydrogenases (Doherty, 1970), glucose-6-phosphate dehydrogenase (Bergmeyer, 1963 ; modified by the use of pH 8 and with the addition of 0.83 units of 6-phosphogluconate dehydrogenase per ml of reaction mixture). Valine aminotransferase was assayed as follows (based on Large & Robertson, 1988): 20 mMsodium 2-oxoglutarate was incubated with 0.1 mM-pyridoxal phosphate, 50 mw-potassium phosphate buffer, pH 7-8, extract and water (final volume, 1 ml).…”