wild-type and the extreme carbon catabolite derepressed mutant A-30 were characterized with respect to enzyme activities, metabolite concentrations and polyol pools all related to glycolysis, after growth on -glucose. In the A-30 strain the enzymes hexokinase and fructose-6-phosphate reductase showed a two- and threefold increase in activity, respectively, whereas phosphofructokinase and pyruvate kinase activity decreased two- and threefold, respectively, in comparison with the wild-type strain. The most notable changes in metabolite concentrations were that fructose 2,6-bisphosphate and fructose 1,6-bisphosphate showed a 2.5-fold increase, whereas both pyruvate and citrate decreased in the A-30. Striking differences were found for the polyol concentrations measured for the two strains tested. Intracellular glycerol and arabitol concentrations were 10-fold higher and erythritol fivefold higher in , whereas intracellular trehalose and mannitol were both decreased. The total internal polyol concentration appears to be constant at ~ 700 μmol (g dry wt). All polyols were also detected in high amounts in the culture filtrate of the mutant strain but no extracellular trehalose was found. The overall production of polyols in this strain was therefore much higher than in the wild-type. The high level of polyols produced and the changes in metabolite concentrations in the strain suggest that the differences in enzyme activities result in an altered flow through glycolysis leading to a more rapid formation of polyols which are subsequently secreted.


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