Mukherjee A, Ghosh S
J Bacteriol. 1987 Sep;169(9):4361-7. doi: 10.1128/jb.169.9.4361-4367.1987.
Fructose uptake and catabolism in Azospirillum brasilense is dependent on three fructose-inducible enzymes (fru-enzymes): (i) enzyme I and (ii) enzyme II of the phosphoenolpyruvate:fructose phosphotransferase system and (iii) 1-phosphofructokinase. In minimal medium containing 3.7 mM succinate and 22 mM fructose as sources of carbon, growth of A. brasilense was diauxic, succinate being utilized in the first phase of growth and fructose in the second phase with a lag period between the two growth phases. None of the fru-enzymes could be detected in cells grown with succinate as the sole source of carbon, but they were detectable toward the end of the first phase of diauxie. All the fru-enzymes were coinduced by fructose and coordinately repressed by succinate. Studies on the effect of succinate on differential rates of syntheses of the fru-enzymes revealed that their induced syntheses in fructose minimal medium were subject to transient as well as permanent (catabolite) repression by succinate. Succinate also caused a similar pattern of transient and permanent repression of the fructose transport system in A. brasilense. However, no inducer (fructose) exclusionlike effect was observed as there was no inhibition of fructose uptake in the presence of succinate with fructose-grown cells even when they were fully induced for succinate uptake activity.
巴西固氮螺菌中果糖的摄取和分解代谢依赖于三种果糖诱导酶（fru-酶）：（i）磷酸烯醇丙酮酸：果糖磷酸转移酶系统的酶I和（ii）酶II，以及（iii）1-磷酸果糖激酶。在含有3.7 mM琥珀酸和22 mM果糖作为碳源的基本培养基中，巴西固氮螺菌的生长是双相的，琥珀酸在生长的第一阶段被利用，果糖在第二阶段被利用，两个生长阶段之间有一个滞后期。在用琥珀酸作为唯一碳源生长的细胞中检测不到任何fru-酶，但在双相生长的第一阶段结束时可以检测到它们。所有的fru-酶都由果糖共同诱导，并被琥珀酸协同抑制。对琥珀酸对fru-酶合成差异速率的影响的研究表明，它们在果糖基本培养基中的诱导合成受到琥珀酸的瞬时和永久（分解代谢）抑制。琥珀酸还对巴西固氮螺菌中的果糖转运系统产生了类似的瞬时和永久抑制模式。然而，没有观察到诱导剂（果糖）排除样效应，因为即使在琥珀酸存在下，果糖生长的细胞在完全诱导琥珀酸摄取活性时，果糖摄取也没有受到抑制。
