| In recent years,the biological nitrogen fixation in crops and nitrogen-fixing trees was extensively pays more attention,but the biological nitrogen fixation in non nitrogen-fixing trees was little investigated.Most of the constructive species of forest vegetation was non nitrogen-fixing trees.It is necessary to study the diversity of rhizosphere nitrogen fixing bacteria in forest areas,in order to provide a theoretical basis for the sustainable development of forest ecosystems which was composed of non nitrogen fixing tree.In our study,the rhizosphere soil of non nitrogen fixing tree species were collected,the tree species grown in Five locations of Inner Mongolia,which respectively were Genhe ecological station in Greater Khingan Range,Arxan national forest park,Wangyedian national forest park,Mount Daqing nature reserve in Hohhot and Helan Mountains nature reserve.The nitrogen-fixing bacteria were isolated and purified from the rhizosphere soil by Ashby nitrogen-free culture medium,the 16 S rDNA of nitrogen-fixing bacteria was amplified by primers 27 f /1492 r and sequenced,Neighbor-joining tree built with DNAMAN6.0 and MEGA 4,then they were identified in morphological the 16 S rDNA and physiology biochemical.The growth characteristics and the Phosphate solubilizing capacity of the isolated nitrogen fixing bacteria were determined,The nitrogen fixing bacterial community in the rhizosphere soil which was from the five locations of Inner Mongolia was analyzed.The main results are as follows:1.The 88 strains of nitrogen fixing bacteria which were isolated from are rhizosphere soil of Larixgmelinii,Betula platyphylla and Populus davidiana Dode in Genhe ecological station to 19 generas,they were respectively Burkholderia(34 strains)?Pseudomonas(19 strains)?Paenibacillus(8 strains)?Brevundimonas(2 strains)?Rhizobium(4 strains)?Filimonas(2 strains)?Bacillus(3 strains)?Mitsuaria(3 strains)?Ochrobactrum(1 strains)?Pantoea agglomerans(1 strains)?Sphingomonas(1 strains)?Acinetobacter(1 strains)?Naxibacter(1 strains)?Salinicoccus(1 strains)?Dyadobacter(1 strains)?Phyllobacterium(1 strains)?Variovorax(1 strains)?Xanthomonas(1 strains)and Agrobacterium(2 strains),Among them,Burkholderia(38.6%),Pseudomonas(21.6%)were dominant genera.Eight of them which had phosphate solubilizing activity were screened,they were respectively Burkholderia(3 strains)?Pseudomonas(3 strains)?Brevundimonas(1 strains)?Naxibacter(1 strains)and Paenibacillus(1 strains).2.The 72 strains of nitrogen fixing bacteria which were isolated from are rhizosphere soil of Larixgmelinii,Betula platyphylla and Populus davidiana Dode in Arxan National Forest Park belonged to 17 generas,they were respectively Pseudomonas(23 strains)?Bacillus(4 strains)?Paenibacillus(8 strains)? Rhizobium(9 strains)?Enterobacter(6 strains)?Phyllobacterium(5 strains)?Bosea(4 strains)?Burkholderia(2 strains)?Variovorax(2 strains)?Chitinophaga(1 strains)?Klebsiella(1 strains)?Arthrobacter(2 strains)?Serratia(1 strains)?Caulobacter(1 strains)?Mucilaginibacter(1 strains)?Mesorhizobium(1 strains)?Labrys(1 strains).Among them,Pseudomonas(31.9%)were dominant genera.Eight of them which had phosphate solubilizing activity were screened,they were respectively Pseudomonas(2 strains)?Paenibacillus(3 strains)?Enterobacter(1 strains)and Phyllobacterium(1 strains).3.The 143 strains of nitrogen fixing bacteria which were isolated from are rhizosphere soil of Larix principis-rupprechtii?Pinus tabulaeformis?Betula platypylla and Populus davidiana Dode in Wangyedian national forest park to 9 generas,they were respectively Pseudomonas(51 strains)?Paenibacillus(41 strains)?Bacillus(32 strains)?Burkholderia(3 strains)?Rhizobium(3 strains)?Phyllobacterium(1 strains)?Arthrobacter(3 strains)?Mucilaginibacter(7 strains)?Mesorhizobium(2 strains),Among them,Pseudomonas(35.7%),Paenibacillus(28.7%),Bacillus(22.4%)were dominant genera.Eight of them which had phosphate solubilizing activity were screened,they were respectively Pseudomonas(3 strains),Paenibacillus(2 strains)?Burkholderia(2 strains)and Bacillus(2 strains).4.The 89 strains of nitrogen fixing bacteria which were isolated from are rhizosphere soil of Pinus tabulaeformis?Betula platypylla and Populus davidiana Dode in Mount Daqing Nature Reserve,to 14 generas,they were respectively Pseudomonas(32 strains)?Phyllobacterium(15 strains)?Arthrobacter(1 strains)?Sinorhizobium(8 strains)?Enterobacter(6 strains)?Rhizobium(5 strains)?Burkholderia(4 strains)?Cupriavidus(4 strains)?Bacillus(1 strains)?Paenibacillus(1 strains)?Promicromonospora(2 strains)?Massilia(1 strains)?Azotobacter(1 strains)and Hymenobacter(1 strains),Among them,Pseudomonas(40%),Phyllobacterium(16.9%)were dominant genera.Eight of them which had phosphate solubilizing activity were screened,they were respectively Pseudomonas(3 strains)?Burkholderia(1 strains)?Bacillus(1 strains).5.The 60 strains of nitrogen fixing bacteria which were isolated from are rhizosphere soil of Pinus tabulaeformis and Populus davidiana Dode in Helan Mountains Nature Reserve,to 8 generas,they were respectively Phyllobacterium(18 strains)?Rhizobium(13 strains)?Pseudomonas(12 strains)?Arthrobacter(8 strains)?Bacillus(6 strains)?Paenibacillus(1 strains)?Caulobacter(1 strains)and Massilia(1 strains),Among them,Rhizobium(21.7%),Pseudomonas(18.3%)were dominant genera.Eight of them which had phosphate solubilizing activity were screened,they were respectively Pseudomonas?Paenibacillus?6.The groups of nitrogen-fixing Bacteria from different geographical regions and different distribution were different,Some groups were widely distributed,as Pseudomonas?Bacillus?Rhizobium?Paenibacillus and Phyllobacterium were all separated from the Rhizosphere soils in Five locations.The distribution of some groups is regional.There were significant differences in their biological characteristics. |
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