膜荚黄芪根瘤菌DNA的G+Cmol%测定及DNA-DNA杂交

在数值分类的基础上,利用复性速率液相分子杂交法及热变性温度法(Tm)对采自甘肃的膜荚黄芪根瘤菌进行了DNA-DNA杂交及G+Cmol%测定.结果表明,待测菌株的之间的DNA同源性大于70%,而与参比菌株的DNA同源性均低于70%;G+C mol%为63.7%.表明此新群为1个不同于已知种的、独立的DNA同源群.

DNA-DNA Hybrization and G+C mol% Test of Rhizobia Isolated from Astragalus Membranceus

Based on the previous studies on numerical taxonomy,the rhizobial strains isolated from nodules of Astragalus membranceus grown in Gansu province of China constituted a new cluster.The contents of G+C mol% of all examined strains were measured,and DNA-DNA homologies among the strains with in one group as well as DNA-DNA homologies between center strain of one group and reference strains of some known species were analyzed.The results showed that DNA-DNA homologies among strains within the group were above 70%;ΔTm of three groups were below 5 ℃;The DNA-DNA isogenesis idex among center strains of the group and type strains of known rhizobium species were much below 70%.All these results indicate that the group are the new DNA homologous group and different from known rhizobium species.The contents of G+C mol% of the group is 63.7%.Thus,the center strain represented a new rhizobia species.