Oxalic acid production by Aspergillus niger:: an oxalate-non-producing mutant produces citric acid at pH 5 and in the presence of manganese
Oxalic acid production by Aspergillus niger:: an oxalate-non-producing mutant produces citric acid at pH 5 and in the presence of manganese
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DOI：
10.1099/00221287-145-9-2569
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发表时间：
1999-09-01
期刊：
影响因子：
2.8
通讯作者：
Visser, J
中科院分区：
文献类型：
--
作者：
Ruijter, GJG;van de Vondervoort, PJI;Visser, J
外界pH值是尼日尔曲霉产草酸的主要影响因素。尼日尔曲霉产生的葡萄糖氧化酶阴性突变株。一个葡萄糖氧化酶阴性的突变体只要培养物的ph值在3或更高就能产生大量的草酸。当ph值降低到2以下时，没有草酸生成。草酰乙酸乙酰水解酶（OAH）是A.尼日尔，与草酸生产。OAH是从A.尼日尔和特点。OAH能将草酰乙酸裂解为草酸盐和乙酸盐，而A.尼日尔从未在培养液中积累任何乙酸盐。自从A.黑尼日尔acuA突变体，缺乏乙酰辅酶A合酶，确实产生一些乙酸，野生型A。尼日尔显然能够足够快地分解代谢乙酸以防止其产生。了全境先前在筛选胞外蛋白酶表达缺陷的菌株中分离的尼日尔突变体prtF28在此显示为不产生草酸。prtF28突变体缺乏OAR，这意味着OAH是A.尼日尔.在传统的柠檬酸发酵中，低pH和缺乏Mn 2+是先决条件。值得注意的是，缺乏葡萄糖氧化酶（goxC）和OAH（prtF）的菌株在pH 5的常规合成培养基中从糖底物产生柠檬酸，并且在这些条件下，生产对Mn 2+完全不敏感。
The external ph appeared to be the main factor governing oxalic acid production by Aspergillus niger. A glucose-oxidase-negative mutant produced production ay Aspergillus niger. A glucose-oxidase-negative mutant produced substantial amounts of oxalic acid as long as the ph of the culture was 3 or higher. When ph was decreased below 2, no oxalic acid was formed. The activity of oxaloacetate acetylhydrolase (OAH), the enzyme believed to be responsible for oxalate formation in A. niger, correlated with oxalate production. OAH was purified from A. niger and characterized. OAH cleaves oxaloacetate to oxalate and acetate, but A. niger never accumulated any acetate in the culture broth. Since an A. niger acuA mutant, which lacks acetyl-CoA synthase, did produce some acetate, wild-type A. niger is apparently able to catabolize acetate sufficiently fast to prevent its production. An A. niger mutant, prtF28, previously isolated in a screen for strains deficient in extracellular protease expression, was shown here to be oxalate nonproducing. The prtF28 mutant lacked OAR, implying that OAH is the only enzyme involved in oxalate production in A. niger. In a traditional citric acid fermentation low ph and absence of Mn2+ are prerequisites. Remarkably, a strain lacking both glucose oxidase (goxC) and OAH (prtF) produced citric acid from sugar substrates in a regular synthetic medium at ph 5 and under these conditions production was completely insensitive to Mn2+.