沙坡头地区根瘤菌DNA同源性及16SrDNA全序列

STUDIES ON DNA DNA HYBRIDIZATION AND 16S rDNA SEQUENCE OF RHIZOBIA ISOLATED FROM SHAPOTOU DESERT SOIL IN NINGXIA AOTONOMOUS REGION OF CHINA

数值分类和多位点酶电泳分析表明，分离自宁夏沙坡头地区的１２株根瘤菌构成一个独立的表观群。对这一菌群进行了ＤＮＡ同源性和群内中心菌株１６ＳｒＤＮＡ全序列分析。１２个菌株的Ｇ＋Ｃｍｏｌ％在５６４～６２２范围内；群内ＤＮＡ同源性为７２３％～９３５％，大于７０％，属种内水平；中心株Ｎ２２０的１６ＳｒＤＮＡ全序列与参比菌株的序列比较，从模拟系统发育树看出，它与三株土壤杆菌、三株根瘤菌的１６ＳｒＤＮＡ序列同源性在９４８％～９９２％的相似性水平上构成一个分支，看来沙坡头地区这群根瘤菌是一个独立的新种群。

Based on the previous studies on numerical taxonomy and multilocus enzymes electrophoresis patterns of the 12 rhizobial strains isolated from Shapotou region, the contents of G+C mol%, DNA DNA relatedness and 16SrDNA sequence of the representative strain were tested.The DNA G+C content of the members of this group ranged from 56 4 to 62 2.The values of DNA DNA hybridization within the group were above 70%, and relatendness between representative strains of this group and known rhizobial species was below 66 6%.The full length of 16S rDNA sequence of representative strain N220 was compared with the type strains of all konow rhizobia species and related bacteria by the PHLIP version 3 572c composed a unrooted phylogenetic tree, the strain N220, R.galegea, two unnamed rhizobial strains(SH19312,SH22623)and three Agrobacterium strains constituted a branch in this tree.The similarity values of 16S rDNA sequence between strain N220 and other strains in this branch were above 95%.