巴西固氮螺菌(Azospirillum brasilience)宿主专一性基因突变体的筛选

SCREENING FOR MUTANTS OF HOST SPEGIFIC GENE IN Azospirillum brasilience

通过接合转移法将带有转座子Tn5的自杀质粒从供体茵(E.coliHB101/P^(GSq)∷Tn5)转移到巴西固氮螺菌(Azspirillum brasilience Sp^7)上。接合转移率可达 10^(-6)/1个受体细胞。得到的接合转移子显示典型的A.brasilience特征和很高的固N酶活性。300个接合转移子只带有转座子Tn5的Km(卡那霉素)抗性标记,而没有载体质粒(P^(GSq))的Cm(氯霉素)抗性标记。化学趋向性试验,发现2个与玉米根系抽提物缺乏亲和反应、频率为2.5×10^(-2)的突变株,试验证明,转座子插入诱变结合化学趋向性反应是固N螺菌宿主专一性基因分析的有效方法。

Suicide plasmid harboring Tn5 was transferred from donor (E. coli HB101/P ~q∷Tn5) to recipient (A. brasilionce Sp^7) through conjugation. The frequency of transconjugation might reach 10^(-6) per recipient cell. Tne tran conjugants expressed the typical characteristics of A. brasili- ence and the nitrogenase activities were high. The transconjugants were resistart to Km (Tn5), but not resistant to Cm (P^(GSq)). Chemotaxis were conducted, two in with mutants were discovered to be not compatible with the extracts of maize root The frequency is 2.5×10^(-2). The results indicated that transposon mutagenesis combining with chemotaxis was a very efficient method for host specific gene analysis of A. brasilience.