Citric acid accumulation by cycloheximide-sensitive mutant strains of Aspergillus niger
Citric acid accumulation by cycloheximide-sensitive mutant strains of Aspergillus niger
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黑曲霉放线菌酮敏感突变株的柠檬酸积累
DOI：
10.1007/s002530050644
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发表时间：
2009
影响因子：
5
通讯作者：
Shoji Usami
中科院分区：
文献类型：
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作者：
Sugima Rugsaseel;Kotaro Kirimura;Shoji Usami
从黑曲霉WU-2223L出发，对一株柠檬酸超积累菌株的放线菌环己酰亚胺敏感突变体进行了诱变。筛选是基于这样一个假设，即突变株对环己亚胺的敏感性高于WU-2223L。在不含甲醇的摇瓶培养中，7个突变株积累的柠檬酸约为吴-2223L的1.8-3.5倍。最好的突变株CHM I-C3在无甲醇摇瓶培养中，从120 mg葡萄糖/ml中积累了69.4 mg柠檬酸，是吴-2223L在甲醇中积累柠檬酸的1.1倍。此外，在不含甲醇的条件下，突变株利用消耗的葡萄糖积累柠檬酸的效率高于吴-2223L。研究还证实，CHM I-C3细胞内NH4+积累水平显著增加。添加2%(v/v)甲醇或20μg放线菌素/ml可显著提高WU-2223L的柠檬酸积累，分别为对照的3.1倍和2.4倍。然而，这些物质的添加对突变株的柠檬酸积累产生了负面影响。在甲醇浓度为2%(v/v)时，吴-2223L的蛋白质积累水平显著降低，但胞内NH4+积累水平显著增加。然而，在没有甲醇的CHM I-C3中也观察到了这些现象。这些结果表明，不含甲醇的放线菌亚胺敏感突变体的胞内环境与含甲醇的WU-2223L相似，蛋白质合成受阻是导致突变株在无甲醇条件下柠檬酸积累增加的原因之一。
Mutants having impaired protein synthesis, that is cycloheximide-sensitive mutants of a citric-acid-hyper-accumulating strain, were induced fromAspergillus nigerWU-2223L. Selection was on the basis of a presumption that the mutants should be more sensitive to cycloheximide than WU-2223L. In shake culture without methanol as a promotor substance, seven mutants accumulated approximately 1.8–3.5 times as much citric acid as WU-2223L. The best mutant, CHM I-C3, accumulated 69.4 mg citric acid/ml from 120 mg glucose/ml in shake culture without methanol, this amount being 1.1 times the amount accumulated by WU-2223L with methanol. Furthermore, under the conditions without methanol the mutants appeared to be more efficient than WU-2223L in employing the consumed glucose for the accumulation of citric acid. It was also confirmed that CHM I-C3 exhibited a significantly increased level of intracellular NH4+accumulation. The addition of 2% (v/v) methanol or 20 μg cycloheximide/ml to the medium caused a remarkable increase of citric acid accumulation by WU-2223L: about 3.1 and 2.4 times respectively. However, the addition of these substances produced negative effects on citric acid accumulation by the mutants. With 2% (v/v) methanol, WU-2223L showed a remarkably decreased level of protein accumulation but a substantially increased level of intracellular NH4+accumulation. However, these phenomena were also observed in CHM I-C3 without methanol. These results indicate that the intracellular circumstances of the cycloheximide-sensitive mutants without methanol were similar to those of WU-2223L with methanol, and that the impairment of protein synthesis contributed to increased citric acid accumulation by the mutants in the absence of methanol.