Abstract

We collected the nodules of Sophora alopecuroides from a number of locations in Xinjiang, China. From these nodules, we isolated 67 previously unknown strains of rhizobia. We analyzed the phenotypic characteristics and the numerical taxonomy of these rhizobia and 36 reference strains through 118 parameters. The results showed that the strains differed in some characteristics, including carbon and nitrogen source, resistance to antibiotics and chemical dye, and endurance to salt and alkali. All unknown strains were tolerant to low temperature, and grew in YMA medium with an initial pH from 9 to 12. Up to 92.5% of the strains were able to grow on YMA medium containing 3.0% NaCl, and more than 91.0％ were able to grow on YMA medium containing 4.0% NaCl. Eighteen strains were able to tolerate NaCl concentrations as high as 5%-6% in the growth medium. The unknown strains formed four new clusters defined by at least 84.8% similarity. Cluster I had 21 strains and NWBC152 was the central strain. Cluster II had 7 strains and NWTKX101 was the central strain. Cluster III had 4 strains and NWYJS12 was the central strain. Cluster IV had 3 strains and NWLP112 was the central strain. In addition, the numerical taxonomic analysis indicates that some strains in the new clusters could be new taxa.