利用抗CTP合成酶反馈抑制筛选胞苷高产突变株
Screening of cytidine-producing mutants based on feedback-inhibition resistance of CTP synthetase
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摘要: 目的 ： 通过解除对CTP合成酶的反馈抑制，得到胞苷高产突变株。 方法 ： 以胞苷脱氨酶缺失的枯草芽孢杆菌为出发菌株进行亚硝基胍（NTG）诱变，用6-氮杂尿嘧啶（6-AU）、5-氟胞苷(5-FCR)和3-脱杂氮尿嘧啶(3-DU)3种嘧啶结构类似物进行抗性筛选。 结果 ： 筛选得到突变株K-215，研究表明其抗6-AU、5-FCR和3-DU的浓度分别是0.9 mg/mL，3.5 mg/mL和4.5 mg/mL；突变株CTP合成酶的活性为出发菌株的6.2倍，37 ℃培养80 h积累胞苷可达6.2 mg/mL。 结论 ： 突变株K-215能够累积胞苷且CTP合成酶的反馈抑制得到部分解除。Abstract: Aim ：To obtain a mutant which could increase the yield of cytidine by decreasing the feedback-inhibition of CTP synthetase. Methods ：A cytidine deaminase deficient strain was induced mutation by nitrosoguanidine（NTG） and screened with pyrimidine analogs，to obtain 6-azauracil，5-fluorocytidine and 3-deazauracil resistant strains. Results ：A mutant of Bacillus subtilis K-215 was obtained，with the critical resistance concentration to 6-azauracil，5-fluorocytidine and 3-deazauracil being 0.9，3.5 and 4.5 mg/mL，respectively.The CTP synthetase activity of the mutant was increased by 5.2 fold and cytidine was accumulated to 6.2 mg/mL after 72 h fermentation at 37 ℃. Conclusion ：The mutant K-215 has higher cytidine productivity and is partially free from the feedback-inhibition on CTP synthetase.
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Keywords:
- cytidine /
- CTP synthetase /
- resistance screening /
- Bacillus subtilis
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