van der Veen P, Ruijter G J, Visser J
Wageningen Agricultural University, Section of Molecular Genetics of Industrial Microorganisms, The Netherlands.
Microbiology (Reading). 1995 Sep;141 ( Pt 9):2301-6. doi: 10.1099/13500872-141-9-2301.
Aspergillus nidulans wild-type and the extreme carbon catabolite derepressed mutant creAd-30 were characterized with respect to enzyme activities, metabolite concentrations and polyol pools all related to glycolysis, after growth on D-glucose. In the creAd-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 creAd-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 creAd-30, whereas intracellular trehalose and mannitol were both decreased. The total internal polyol concentration appears to be constant at approximately 700 mumol (g dry wt)-1. All polyols were also detected in high amounts in the culture filtrate of the creAd-30 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 creAd-30 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.
在以D-葡萄糖为碳源生长后，对构巢曲霉野生型和极端碳分解代谢物阻遏解除突变体creAd-30进行了与糖酵解相关的酶活性、代谢物浓度和多元醇库的表征。在creAd-30菌株中，己糖激酶和6-磷酸果糖还原酶的活性分别增加了两倍和三倍，而与野生型菌株相比，磷酸果糖激酶和丙酮酸激酶的活性分别降低了两倍和三倍。代谢物浓度最显著的变化是，creAd-30中的2,6-二磷酸果糖和1,6-二磷酸果糖增加了2.5倍，而丙酮酸和柠檬酸均减少。在所测试的两种菌株中，多元醇浓度存在显著差异。creAd-30中的细胞内甘油和阿拉伯糖醇浓度高10倍，赤藓糖醇高5倍，而细胞内海藻糖和甘露醇均减少。细胞内多元醇总浓度似乎恒定在约700 μmol（每克干重）-1。在creAd-30突变菌株的培养滤液中也检测到大量的所有多元醇，但未发现细胞外海藻糖。因此，该菌株中多元醇的总体产量远高于野生型。creAd-30菌株中产生的高水平多元醇和代谢物浓度的变化表明，酶活性的差异导致糖酵解通量改变，从而导致多元醇更快形成并随后分泌。
