Mukhtar Hamid, Ijaz Syeda Sidra
Institute of Industrial Biotechnology, GC University, Lahore, 54000, Pakistan,
Cell Biochem Biophys. 2014 Sep;70(1):309-20. doi: 10.1007/s12013-014-9914-7.
The present study describes the enhanced production and purification of lovastatin by Aspergillus terreus in submerged batch fermentation. The enhancement of lovastatin production from A. terreus was attempted by random mutagenesis using ultraviolet radiations and nitrous acid. UV mutants exhibited increased efficiency for lovastatin production as compared with nitrous acid mutants. Among all the mutants developed, A. terreus UV-4 was found to be the hyper producer of lovastatin. This mutant gave 3.5-fold higher lovastatin production than the wild culture of A. terreus NRRL 265. Various cultural conditions were also optimized for hyper-producing mutant strain. 5 % glucose as carbon source, 1.5 % corn steep liquor as nitrogen source, initial pH value of 6, 120 h of incubation period, and 28 °C of incubation temperature were found as best parameters for higher lovastatin production in shake flasks. Production of lovastatin by wild and mutant strains of A. terreus was also scaled up to laboratory scale fermentor. The fermentation process was conducted at 28 °C, 200 rpm agitation, and 1vvm air flow rate without pH control. After the optimization of cultural conditions in 250 ml Erlenmeyer flasks and scaling up to laboratory scale fermentor, the mutant A. terreus UV-4 gave eightfold higher lovastatin production (3249.95 μg/ml) than its production by wild strain in shake flasks. Purification of lovastatin was carried out by solvent extraction method which yielded 977.1 mg/l of lovastatin with 98.99 % chromatographic purity and 26.76 % recovery. The crystal structure of lovastatin was determined using X-ray diffraction analysis which is first ever reported.
本研究描述了土曲霉在分批深层发酵中洛伐他汀产量的提高及纯化方法。通过紫外线辐射和亚硝酸进行随机诱变，试图提高土曲霉洛伐他汀的产量。与亚硝酸突变体相比，紫外线突变体表现出更高的洛伐他汀生产效率。在所有诱变产生的突变体中，土曲霉UV-4被发现是洛伐他汀的高产菌株。该突变体产生的洛伐他汀比土曲霉NRRL 265野生菌株高出3.5倍。还对高产突变菌株的各种培养条件进行了优化。发现5%葡萄糖作为碳源、1.5%玉米浆作为氮源、初始pH值为6、培养期120小时以及培养温度28℃是摇瓶中洛伐他汀高产的最佳参数。土曲霉野生菌株和突变菌株的洛伐他汀生产也扩大到实验室规模的发酵罐。发酵过程在28℃、200 rpm搅拌速度和1vvm空气流速下进行，不控制pH值。在250 ml锥形瓶中优化培养条件并扩大到实验室规模的发酵罐后，突变体土曲霉UV-4产生的洛伐他汀比其在摇瓶中的野生菌株产量高出八倍（3249.95 μg/ml）。采用溶剂萃取法对洛伐他汀进行纯化，得到977.1 mg/l的洛伐他汀，色谱纯度为98.99%，回收率为26.76%。使用X射线衍射分析确定了洛伐他汀的晶体结构，这是首次报道。
