Diversity Analysis Of Culturable Bacteria From Xerophyte Haloxylon Ammodendron Rhizosphere

In the arid and semi-arid areas of China, with the increase of global climate changes and the range of human activities, desertification is also increasingly common. Desertification not only causesa reduction in available land resources but also increases the recession of environmental loading forces and the frequency of sandstorm. This harsh environment makes a great challenge for the growth of organisms. The vegetation grows in arid and semi-arid regions of western plays a decisive role in fighting against desertification in western China. And Haloxylon ammodendron plant community composition which called “desert forest” has a pivotal position in it. How to make the extensive growth of Haloxylon ammodendron that can slow down even eliminate desertification in the western desert region is a challenge must be taken into account. In recent years, people increasingly focuse on the study of PGPR. Because they can not only promote plant growth, reduce pests and diseases, but also decrease the use of fertilizer and pesticides which has great destructiveness to the people and environment. We analyze the diversity of rhizosphere soil bacteria which grow with different enclosure years in the Minqin of the Gansu province and Alxa youqi of the Inner Mongolia, in order to illustrate the similarities and differences of Haloxylon ammodendron rhizosphere bacterial diversity in the Badain Jaran Desert and Tengger Desert confluent area. And then we can find strain resources with good growth-promoting properties which can be adapt to the harsh desert environment.We selected 16 Haloxylon ammodendron rhizosphere soil samples with different enclosure years in the Minqin of the Gansu province and Alxa youqi of the Inner Mongolia. We isolated and purified cultured bacteria. And then we analyzed similarities and differences to culturable bacterial diversity based on 16 S rRNA gene sequencing results and phylogenetic tree analysis. After that, we classified and identified a candidate strain which may be a new species in Altererythrobacter in detail. The main results are as follows: 1. From the results we got, the culturable bacterial community composition and the preponderantcolony in two deserts are nearly same. Overall the soil water content and soil conditions inMinqin was better than the Alxa youqi, and the bacteria diversity in Minqin was slightly betterthan the Alxa youqi in rhizosphere soil samples. Meanwhile, there were unique strains in twodesert. 2. From four rhizosphere soil samples that has no Haloxylon ammodendron and twelverhizosphere soil samples that has different planting years Haloxylon ammodendron, we isolatedculturable bacteria 292 strains and they belonged to six phylogenetic groups: Actinobacteria,Firmicutes, Bacteroidetes, α-Proteobacteria, γ-Proteobacteria and β-Proteobacteri. 3. Through a series of identification and phylogenetic research, we obtained 36 strains whichmight be new representative spcies of bacterial genus and they occupied about 9.4% of the totalnumber of isolated strains. Further studies have been completed and we identified a newspecies of the genus Altererythrobacter, named as Altererythrobacter soli. 4. In the process of Haloxylon ammodendron rhizosphere soil culturable bacterial diversityresearch, we also got some strains with PGPR characteristics. At present, we conducted ainteraction experiment with model plant Arabidopsis thaliana and WM13-24 which belongedto the genus Bacillus. The result had initially shown good growth-promoting effect toArabidopsis thaliana. And further studies are in progress.Above results showed that there were unique culturable strains in Haloxylon ammodendron rhizosphere soil samples in Minqin and Alxa youqi desert. They enriched the microbial species resources in extreme environmental in our country to a certain extent. And they provide a scientific basis for the study and utilization in microbial resources under high saline and drought conditions. The strains with PGPR characteristics provided rich microbial resources for us to develop microbial fertilizer with stress resistance and growth-promoting character, and improve the research and application of stress resistance ability of artificial Haloxylon ammodendron and plantation crop next step.