【作者】 刘小钟；

【导师】 李洪连；

【作者基本信息】 河南农业大学 ， 植物病理学， 2003， 硕士

【摘要】 024菌株是河南农业大学植物病理研究室从土壤中分离出来的对引起小麦纹枯病(Wheat sharp eyespot)的禾谷丝核菌(Rhizoctonia cerealis)有着强抑制力的放线菌菌株。鉴于024菌株是一株野生型菌株，本文首先对该菌株的一些生物学特性进行了研究，然后又以该菌株为出发菌株，以禾谷丝核菌(Rhizoctonia cerealis)为指示菌株，利用一些理化因子，对该菌株进行了诱变育种，并通过摇瓶发酵实验筛选到了5株抑菌效果增加在10％以上的高效突变株。同时，本文还对所使用的不同诱变剂的诱变效应进行了评估和比较。其主要内容有以下几个方面： 1．024菌株的生物学特性：在所测试的各种培养基中，PDA是最适合024菌株生长的培养基，并以培养三周时的产孢量最大；摇瓶发酵实验表明，024菌株的发酵周期约为168h，菌丝最大生长量在发酵72h，产抗生素高峰在发酵96h，发酵液滤液pH与初始pH相比呈现先降(从0-12h是下降阶段)，至酸性，后升(12h以后阶段)，至碱性；在发酵培养基的装液量方面，该菌株无严格要求；在接菌量方面，以1％的接菌量最佳。 2．不同的物理和化学诱变剂处理024菌株的结果表明，不同的诱变剂对该菌株有着不同的致死效应。通过诱变育种，利用平板对峙培养的初筛方法，共获得了26株高效突变株。其中，微波诱变处理筛选到了7株，亚硝基胍(NTG)诱变处理筛选到了19株，而紫外线和氯化锂(LiCl)诱变处理均未筛选到高效突变株。 3．通过对所使用的各种诱变剂诱变效应的分析和比较，得出：在这四种诱变剂中，亚硝基肌（NTG）和微波的诱变效应强于氯化理几汇1）和紫外线的诱变效应，其中又以亚硝基肌（NTG）的诱变效应最强。 4．通过对初筛得到的26株高效菌株的摇瓶发酵实验，获得了七株优良菌株，其中有四株抑菌效果增效超过10儿 它们是N132、MW50S。。NI－2、NI－20和MW100Su，与出发菌株一024菌株相比，它们 的抑菌效果分另提高了 15．52＊、14．38＊、12．95％、12．19＊和 10．19＊。更多还原

【Abstract】 024 strain, which was screened from soil by Plant Pathology Lab. ofHenan agricultural university, inhibits Rhizotonia cerealis intensely which can cause Wheat sharp eyespot. Based on previous research, it was found that 024 strain showed its inhibitory effect by producing antibiotic. Seeing that 024 strain is a wild-type one, this paper studied its biological characteristics firstly, and then, taking 024 strain and Rhizotonia cerealis as a starting strain and an indicative strain respectively, its spores were treated by some physical and chemical factors to improve it using mutative breeding. Finally, 5 high-yield strains were obtained. At the same time, the mutative effects of all mutative factors in the experiment were evaluated and compared with each other, too. The main content of this paper is described as the following:1) 024 strain’s biological characteristics: In all culture media which were tested, Potato Dextrose Agar (PDA) was the best one for 024 strain growth, on which there was the most spore population after it was cultured for 3 weeks. By the fermenting experiment in shaking flasks, it was showed that the fermenting period of 024 strain was about 168h. During this process, there was the biggest value on the growth of mycelium and the yield of antibiotic after 024 strain was fermented for 72h and 96h respectively. Compared with the initial pH7.0, the pH of the fermenting liquid showed that there was a decline (from Oh to 12h, showing acid) firstly, and then, there was a rise (after 12h, showing alkalinity). On the volume of fermenting culture medium in shaking flasks, 024 strain had no strict request. In all inoculation volume treats, 1% was the best one.2) After 024 strain was treated by different mutative factors, the results showed that they had different mortal effect on it. By mutative breeding and the initial screening method of culturing face to face on a plate, 26 high-yield strains were obtained, of which 7 ones were from microwave treat, 19 ones were from Ar-merhyl-A/-nitro-./V-nitrosoguanidine (NTG) treat and no one was from ultraviolet treat or LiCl treat.3) By analyzing and comparing the mutative effects of different mutative factors, it was concluded that the mutative effects of NTG and microwave were more intense than those of LiCl and ultraviolet, of which NTG was the most intense one.4) By fermenting 26 high-yield strains from the initial screening in shaking flasks, 7 ones of them were thought to be high-yield ones, of which there were 5 ones including Nl-32, MW50s3, Nl-2, Nl-20 and MWlOOsis whose inhibitory effects were more over 10%than that of 024 strain. Compared with 024 strain, their inhibitory effects were improved 15.52%, 14.38%, 12.95%, 12.19% and 10.19% respectively更多还原