Phenotypic Feature Diversities And Phylogenetic Analysis Of Rhizobia Isolated From Glycyrrhiza Linn In Northwest Aride Region Of China

The root nodules from the leguminous plant of Glycyrrhiza Linn which were living in the area of Xinjiang, Shaanxi and Ningxia were studied, 68 uncertain strains were obtained by isolation and purification, and 113 physiology biochemistry properties were measured. The result was clustered by the means of numerical taxonomy. The full length of 16S rDNA of NWGX022 were sequenced by the ABI Prism 377DNA automatic sequencing instrument, NWGX022 was the center strain of group I in the clustering result. Moreover, the DNADIST software was used to analyze the result in order to identify the phylogenetic position of this new group. The growth and the reproduction effect of NWGX035 was measured under the condition of salt, alkali and high temperature stress respectively and the salt, alkali and high temperature combined condition. The property of endurance of salt, alkali and high temperature could provide theory foundation for the discovery of the maximum of endurance of salt, alkali and high temperature, and it also could provide the basis for the selection of good strains. 113 physiology biochemistry properties of 68 strains were analyzed. The result showed that there were great diversities among strains isolated from different geographic origin, the same geographic origin, and the different root nodules of the same root in carbon and nitrogen nutrient utilization, resistance to antibiotics, endurance to salt, alkali. Some strains had the properties of endurance to salt and alkali. 5 strains and 4 strain could endure 50g/L, 60g/L NaCl respectively. 20% and 43% strains could grow in YMA medium with pH5, pH12. Numerical taxonomy showed that the strains formed 3 groups at 85.5% similarity level. Group I contained 27 strains, 23 strains isolated from Xinjiang, 4 isolated from shannxi. Group II had 4 strains isolated from shannxi. Group III ( 6 strains isolated from shannxi, 2 isolated from Ningxia) were clustered into R．hainanense. Group I and Group II may be new groups, which were not clustered into the reference strains, and there taxonomic status must be confirmed by further measurements.In order to determine the phylogenetic position of group, The full length of16S rDNA of NWGX022 was analyzed. The result indicated that all strains clustered into 5 branches in the phylogenetic tree. They were Sinorhizobium, Rhizobium, Rhizo-bium－Agrobacterium, Bradyrhzobium and Mesorhizobium. GroupⅠfell into the Mesorh-izobium branch.The maximum of endurance of salt, alkali and high temperature were measured. The result showed that the reproduction time of NWGX035 was 7.7 hours. at 28 ℃, NWGX035 was able to survive over 5 days in the YMA medium with 0g/L, 20g/L, 40g/L, 60 g/LNaCl, But in the YMA medium with 80g/L NaCl, NWGX035 could survive about 12 hours, It was the maximum endurance of salt of NWGX035. The most suitable growth environment of NWGX035 was PH8, and at pH12, It also could survive over 5 days. Living at 35℃, The NWGX035 was able to survive over 6 days, In 40℃, NWGX035 was able to survive for 12 hours, it was the highest endurance of temperature. Besides, The nodulation with else host experiment told us that NWGX035 could nodulate with melilotus suaveolens Ledeb, sophora alopecuroides Linn, lotus corniculatus Linn, sophora viciifolia Hance, trifolium repens Linn. The property of powerful salt, alkali, high temperature endurance and wide nodulation could confirm this strain was a particular strain. The nodulation mechanism and endurance of salt, alkali and high temperature mechanism need to be studied further.