Siddique Samia, Syed Quratulain, Adnan Ahmad, Qureshi Fahim Ashraf
Department of Chemistry, Government College University Lahore, Lahore, Pakistan.
Food and Biotechnology Research Center, PCSIR Laboratories Complex, Ferozpur Lahore, Lahore, Pakistan.
Jundishapur J Microbiol. 2014 Feb;7(2):e8626. doi: 10.5812/jjm.8626. Epub 2014 Feb 1.
Secondary metabolite production from wild strains is very low for economical purpose therefore certain strain improvement strategies are required to achieve hundred times greater yield of metabolites. Most important strain improvement techniques include physical and chemical mutagenesis. Broad spectrum mutagenesis through UV irradiation is the most important and convenient physical method.
The present study was conducted for enhanced production of avermectin B1b from Streptomyces avermitilis 41445 by mutagenesis using ultraviolet (UV) radiation, ethidium bromide (EB), and ethyl methanesulfonate (EMS) as mutagens.
S. avermitilis DSM 41445 maintained on yeast extract malt extract glucose medium (YMG) was used as inoculum for SM2 fermentation medium. Spores of S. avermitilis DSM 41445 were exposed to UV radiation for physical broad spectrum mutagenesis and to EMS and EB for chemical mutagenesis. For each mutagen, the lethality rate and mutation rate were calculated along with positive mutation rate.
Avermectin B1b-hyper-producing mutant, produced using these three different methods, was selected according to the HPLC results. The mutant obtained after 45 minutes of UV radiation to the spores of S. avermitilis 41445, was found to be the best mutant for the enhanced production of avermectin B1b component (254.14 mg/L). Other avermectin B1b-hyper-producing mutants, were obtained from EMS (1 µL/mL) and EB (30 µL/mL) treatments, and yielded 202.63 mg/L and 199.30 mg/L of B1b, respectively.
The hereditary stability analysis of the UV mentioning 45 minutes revealed the UV exposure time for mutants and 3 represented the colony taken from the plate irradiated for 45 minutes mutant showed that the production of avermectin B1b remained constant and no reverse mutation occurred after 15 generations.
出于经济目的，野生菌株的次级代谢产物产量非常低，因此需要某些菌株改良策略来实现代谢产物产量提高百倍。最重要的菌株改良技术包括物理和化学诱变。通过紫外线照射进行的广谱诱变是最重要且最便捷的物理方法。
本研究旨在通过使用紫外线（UV）辐射、溴化乙锭（EB）和甲磺酸乙酯（EMS）作为诱变剂进行诱变，提高阿维链霉菌41445产阿维菌素B1b的能力。
将保存在酵母提取物麦芽提取物葡萄糖培养基（YMG）上的阿维链霉菌DSM 41445用作SM2发酵培养基的接种物。阿维链霉菌DSM 41445的孢子接受紫外线辐射进行物理广谱诱变，接受EMS和EB进行化学诱变。对于每种诱变剂，计算致死率、突变率以及正向突变率。
根据高效液相色谱（HPLC）结果，选择了使用这三种不同方法产生的阿维菌素B1b高产突变体。对阿维链霉菌41445的孢子进行45分钟紫外线辐射后获得的突变体，被发现是提高阿维菌素B1b组分产量（254.14 mg/L）的最佳突变体。其他阿维菌素B1b高产突变体分别通过EMS（1 µL/mL）和EB（30 µL/mL）处理获得，B1b产量分别为202.63 mg/L和199.30 mg/L。
对提及的45分钟紫外线诱变的遗传稳定性分析表明，突变体的紫外线照射时间以及从照射45分钟的平板上选取的3个菌落表明，阿维菌素B1b的产量保持恒定，在15代后未发生回复突变。
