| Microorganisms are ubiquitous,which not only cause people,plants and animals to be infected with a variety of diseases,but also an important part of the ecological environment,maintaining the balance of ecosystem.How to rationally use microorganisms has always been a hot topic among scientists.As a kind of plant growth promoting rhizobacteria,rhizosphere Bacillus is a widely used as functional microorganism.we dig into the resources of domestic rhizosphere Bacillus strains,build databases and resource banks of chinese rhizosphere Bacillus resources,and analyze the differences of the composition of Bacillus communities in different regions.It is of great significance for the rational development and application of Bacillus resources.In this study,52 samples of rhizosphere soil were collected from 15 provinces and autonomous regions in China in 2018-2019,and the samples were divided into five regions:Northeast China,hebei and Shandong,jiangsu and zhejiang,central China and Southwest China according to the geographical location of the sampling sites.Bacillus spp.resources in rhizosphere soil samples from some crop plants were isolated,identified and preserved,phylogenetic analysis were carried out by using these isolates which belong to Bacillus genera,furthermore,by using high-throughput sequencing of housekeeping gene-gyrA,we analyzed the environmental factors on the community composition of Bacillus and Bacillus related bacteria.The main findings are as follows:1.In this study,27 soil samples were collected from the rhizosphere of crop plants,and 25 soil samples were collected from the rhizosphere of weed plants Bacillus strains in rhizosphere soil of some crop plants were isolated and identified.In total,there were 632 pure cultures,including 369 isolates which belong toBacillus genera and 69 isolates which belong to family Bacillaceae(not belong to Bacillus genera).2.Based on those identified Bacillus strains,we integrated the data and phylogenetic analysis according to the evolutionary information of those strains.Results show that different species of Bacillus strains can coexist in crop plant rhizosphere soil,There were similarities and differences in the species composition of crop plants rhizosphere Bacillus strains in different regions,the preponderant species of Bacillus were different in each region.Some Bacillus strains exist in all sampling area,meanwihle,part of Bacillus strains exist only in certain regions.3.According to the soil fertility,geographical location,climate and other conditions of the crop plants Rhizosphere soil sampling sites,seven representative regions were selected for further analysis.The bacterial species composition and dominant bacterial species of seven regions were analyzed,results further confirmed that both similarities and differences can be observed in the bacterial species composition from the crop rhizosphere in different sampling sites.Phylogenetic analysis were performed based on the isolates from the seven regions,reveals genetic relationship between the parts of Bacillus species in sampling sites,results showed that we can not distinguish the different between the Bacillus aryabhattai,Bacillus huizhouensis and Bacillus megaterium by using 16s rDNA genes.4.In this study,the impact of environmental factors on the community composition of Bacillus and Bacillus related bacteria were analyzed through high-throughput sequencing of house-keeping gene gyrA,The results showed that the Bacillus and Bacillus related bacteria community composition in the plants rhizosphere were significant differences on the basis of certain similarity,no matter based on crop type or location factors.Compared with that of weed plants,the bacterial community in rhizosphere soil of crop plants in China has a higher degree of differentiation.In the Northeast region,Bacillus dominated bacterial communities in the rhizosphere of the plants showed the highest degree of community differentiation,while showed the lowest degree of community differentiation in jiangsu and zhejiang regions.We also found that the difference of community composition of Bacillus were not related to the longitude and latitude.To sum up,this study investigated,collected and preserved the species resources of Bacillus strains in many places in China,analyzed the phylogeny of various Bacillus,and found that the species types and compositions of Bacillus strains in the rhizosphere in different areas had both similarities and differences.This study complemented the resource of rhizosphere Bacillus strains in China,and provided basic information for further development of functional Bacillus strains. |
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