Isolation Of Nitrogen Fixing Bacteria And Study On Effects Of Inoculation With Heysarum Fruticosum Var Mongolicum In Erdos

This dissertation studied on the fixed sandy in Erdos. Nitrogen Fixing Bacteria were isolated from the root of the six fixing sandy plants , namely, Heysarum fruticosum var mongolicum, Caragana intermedia, Salix psammophlia, Sabina Vulgaris, Pinus syvistris var mongolica, Hedysarum scopariu, Artemisia ordosica in Erdos desert. Their nitrogen-fixation enzyme activity, dissolving phosphorite power, dissolving potassium feldspar power and inoculants in Heysarum fruticosum var mongolicum were studied. The main research results were as follows:1. 112 strains, which can subsist on non-nitric medium, were isolated from the root of the six fixing sandy plants Heysarum fruticosum var mongolicum, Caragana intermedia, Salix psammophlia, Sabina Vulgaris, Pinus syvistris var mongolica, Hedysarum scoparium, Artemisia ordosica in Erdos desert.2. Through determining their nitrogen-fixation enzyme activity, 35 strains which enzyme activity was stronger, were found in these strains. 16 strains of nitrogen-fixation enzyme activity exceeded 10 nmol/h·flask, and the strains ZS3 is 123.7 nmol/h·flask, ZS56 is 83.6 nmol/h·flask.3. Through semi-microkjeldahl determination of nitrogen method, we found that the 16 strains whose nitrogen-fixation enzyme activity exceeded 10 nmol/h·flask, which indicated that those have the ability of fixation of nitrogen in the air.4. Through determining their dissolving phosphorite power and dissolving potassium feldspar power of them, 6 strains were found. From the view of phosphate-solubilizing power and dissolving potassium feldspar power we found 16 strains in 35, whose nitrogen-fixation enzyme activity exceeded 10 nmol/h·flask. The phosphorite dissolution diameter was YH510>YC59=YC52>ZS56=HB57>ZS3 in Pikovaskaia'S plate. The strain YC59 had the highest of the phosphorite dissolution reaching to 338.3μg/mL, and strain YC52 reaching to 335.0μg/mL. Ulteriorly determining dissolving potassium feldspar power of 6 strains, the potassium feldspar dissolution diameter of strain YH510 was the most than others reaching to 2.3 cm, and then, the strain ZS3 was the least only 1cm in the plate. But the dissolving potassium feldspar power of ZS56 was the best in the six strains.5. The genomic DNA samples from six strains of nitrogen fixing bacteria were amplified with universal 16S rDNA primers. The products were cloned and sequenced. Homological analysis revealed that the sequences of ZS3 and ZS56 strains were all 1502bp with 98.32% identity. HB57,YC52,YC59 and YH510 strains were all 1450bp with 99.81% identity. From the view of Biolog system, it was concluded that ZS3 belonged to Peseudomona mandelii, ZS56 belonded to Peseudomonas aurantiaca, HB57,YC52,YC59 and YH510 belonged to Rhizobium sp.6.From the view of phosphate-solubilizing power and dissolving potassium feldspar power of 6 strains in 16, whose nitrogen-fixation enzyme activity exceeded 10 nmol/h·flask, it was considered that six strains (ZS3,ZS56,HB57,YC52,YC59 and YH510) have relatively larger potential as inoculants in Heysarum fruticosum var mongolicum. The statistics of inoculants showed that the six strains can promote the growth of Heysarum fruticosum var mongolicum.