Marchal R, Vandecasteele J P, Metche M
Arch Microbiol. 1977 May 13;113(1-2):99-104. doi: 10.1007/BF00428588.
The mechanism of the massive extracellular production of citric and isocitric acids by Saccharomycopsis lipolytica grown on n-paraffins has been studied. When growth stops, because of nitrogen limitation, the intracellular concentration of ATP sharply rises whereas that of AMP and ADP decreases to a low level. At the same time production of acids begins. The activity of the NAD-dependent isocitrate dehydrogenase which requires AMP for activity becomes very low and prevents the oxidative function of the citric acid cycle whereas isocitrate lyase is not inhibited. As citrate synthase inhibition by ATP appears to be insufficient to stop n-paraffin degradation, citric and isocitric acids accumulation can take place. Massive excretion of these acids, however, probably still involves other physiological changes brought about by nitrogen limitation, possibly some permeabilization of the cell to these acids.
对解脂耶氏酵母在正构烷烃上生长时大量胞外产生柠檬酸和异柠檬酸的机制进行了研究。当由于氮限制而停止生长时，细胞内ATP浓度急剧上升，而AMP和ADP浓度则降至低水平。与此同时，酸的产生开始了。需要AMP激活的依赖NAD的异柠檬酸脱氢酶的活性变得非常低，从而阻止了柠檬酸循环的氧化功能，而异柠檬酸裂解酶未受抑制。由于ATP对柠檬酸合酶的抑制似乎不足以阻止正构烷烃的降解，柠檬酸和异柠檬酸得以积累。然而，这些酸的大量排泄可能仍然涉及氮限制引起的其他生理变化，可能是细胞对这些酸的某种通透性改变。
