抗福美双假单胞菌株的NTG化学诱变及分子探针鉴定

利用微生物的抗药性筛选抗福美双的假单胞菌株Ｔ４６，然后通过亚硝基胍（ＮＴＧ）化学诱变获得了对福美双敏感的三株突变株Ｔ４６Ｎ１０、Ｔ４６Ｎ７和Ｔ４６Ｎ１７。利用这三个突变株作受体，通过基因克隆的方法筛选到了可使三个突变株恢复抗性的克隆，抗性基因分别被定位在７ｋｂ、２．５ｋｂ和２０ｋｂ的ＥｃｏＲⅠ片段上。将这三个克隆分别用（３２）Ｐ标记后制成分子探针，然后分别与三个突变菌株的总ＤＮＡ进行ＤＮＡ－ＤＮＡ分子杂交，结果表明，各突变株均存在与菌株Ｔ４６的抗福美双基因克隆的高度同源性，经结合形态、生理生化等分析后证实这三株突变株均源自于出发菌株Ｔ４６。

Mutagenesis of Thiram-resistant Strain T46 of Pseudomonas sp.with Chemical Mutagen Nitrosoguanidine (NTG) and Identification of Mutants with Molecular Probes

A Thiram-resistant strain T46 of Pseudomonas sp. was isolated from the suburbs soil of Nanning and three Thiram-sensitive mutants of the strain were obtained through mutagenesis with chemical mutagen nitrosoguanidine (NTG). Three Thiram-resistant clones isolated from strain T46 with the three mutants as recipies showed that the three clones were able to restore the Thiram resistance of the three mutants respectively, and were located on 7 kb, 2. 5 kb and 20 kb EcoR I fragments respectively. Molecular probes made by labelling the three clones with (32)P respectively were used to probe the total DNA from the mutants.Results from DNA-DNA hybridization indicated that all mutants showed high homology to Thiram-resistant clones from strain T46. With the other data from the analyses of morphogenesis, physiology and biochemistry of strain T46 and its mutants. It was concluded that the three mutants were derived from Pseudomonas strain T46.