Kubicek C P, Schreferl-Kunar G, Wöhrer W, Röhr M
Abteilung für Mikrobielle Biochemie, TU Wien, Vienna, Austria.
Appl Environ Microbiol. 1988 Mar;54(3):633-7. doi: 10.1128/aem.54.3.633-637.1988.
Oxalate accumulation of up to 8 g/liter was induced in Aspergillus niger by shifting the pH from 6 to 8. This required the presence of Pi and a nitrogen source and was inhibited by the protein synthesis inhibitor cycloheximide. Exogenously added 14CO2 was not incorporated into oxalate, but was incorporated into acetate and malate, thus indicating the biosynthesis of oxalate by hydrolytic cleavage of oxaloacetate. Inhibition of mitochondrial citrate metabolism by fluorocitrate did not significantly decrease the oxalate yield. The putative enzyme that was responsible for this was oxaloacetate hydrolase (EC 3.7.1.1), which was induced de novo during the pH shift. Subcellular fractionation of oxalic acid-forming mycelia of A. niger showed that this enzyme is located in the cytoplasm of A. niger. The results are consistent with a cytoplasmic pathway of oxalate formation which does not involve the tricarboxylic acid cycle.
通过将黑曲霉的pH从6调至8，可诱导其草酸盐积累至8克/升。这需要有磷酸根离子（Pi）和氮源的存在，并且会受到蛋白质合成抑制剂放线菌酮的抑制。外源添加的14CO2不会掺入草酸盐中，但会掺入乙酸盐和苹果酸盐中，从而表明草酸盐是通过草酰乙酸的水解裂解进行生物合成的。氟柠檬酸对线粒体柠檬酸代谢的抑制并没有显著降低草酸盐的产量。推测负责此过程的酶是草酰乙酸水解酶（EC 3.7.1.1），它在pH值变化过程中从头诱导产生。对形成草酸的黑曲霉菌丝体进行亚细胞分级分离表明，这种酶位于黑曲霉的细胞质中。这些结果与不涉及三羧酸循环的细胞质草酸盐形成途径一致。
