中文摘要：

目的探索用Fe3O4磁性纳米粒辅助微波诱变来改造无活性放线菌代谢功能的新方法并筛选获得抗肿瘤活性突变株。方法以海洋来源无活性放线菌野生株HLF-43（1000μg/ml样品对K562细胞的抑制率为3.9%）为原始菌,对其孢子悬液在Fe3O4磁性纳米粒子存在下进行微波辐照诱变,再经抗性筛选获得新霉素抗性突变株,并经对原始菌及其突变株的发酵培养与抗肿瘤活性筛选获得活性突变株。采用MTT法用K562细胞测试抗肿瘤活性。结果初步建立了改造放线菌代谢功能的Fe3O4磁性纳米粒辅助微波诱变新方法,并利用该方法由无活性原始株HLF-43筛选获得了新霉素抗性突变株共80株,其中28株发酵样品对K562细胞有抑制活性,100μg/ml浓度下的抑制率大于20%。活性突变株获取率达35%（28/80）,所获活性突变株的遗传性状也较稳定。结论与不加Fe3O4磁性纳米粒子的微波辐照结合新霉素抗性筛选实验相比,该方法更有利于筛选获得高浓度新霉素抗性突变株,同时活性突变株获得率也有大幅度提高,活性突变株的遗传性状也获改进。

英文摘要：

Objective To investigate a new method for altering the secondary metabolism of inactive actinomycete strain by magnetic nanoparticle-aided microwave mutagenesis to obtain antitumor mutants. Methods HLF-43, a marine-derived actinomycete strain without antitumor activity with the inhibition rate of 3.9% at the 1000 μg/ml sample concentration on K562 cells, was used as the initial strain in the present study. The spore suspension of HLF-43 was exposed to the microwave radiation（the frequency 2450 MHz, the power 464 W）under the presence of Fe3O4 magnetic nanoparticles, then spread on neomycin-containing plates and the neomycin-resistant （neo） mutants were selected during incubation at 28℃ for 4-14 days. The initial strain HLF-43 and its neo mutants were fermented to obtain fermentation samples and the antitumor neo mutants were obtained by the test of antitumor activity for these samples at 100 μg/ml. The antitumor activity was assayed by the MTT method using K562 cells. Results A new method has been created for altering the secondary metabolism of actinomycete strain by magnetic nanoparticle-aided microwave mutagenesis. By the method coupled with the neo mutant selection, a total of 80 neo mutants were obtained from the inactive-initial strain HLF-43 and 28 of them were antitumor mutants with the inhibition rates over 20% at the 100 μg/ml sample concentration on the K562 cells. The antitumor mutants could be obtained at quite high frequency of 35%（28/80）. Conclusion Compared with the microwave mutagenesis without the aid of Fe3O4 magnetic nanoparticles, the Fe3O4 magnetic nanoparticle-aided microwave mutagenesis is more favorable to obtain the neo mutants resistant to higher concentration of neomycin and to obtain the antitumor neo mutants at higher frequency.