Research On The Diversity Of Microbial Community In Different Saline-alkaline Soil Ecosystems In China

Saline-alkali soil is an important reserve farmland resource in China.It is a kind of extreme environment with high salt and alkali.It contains rich and diverse microbial community.In this paper,32 saline-alkaline soil samples from different regions of northwest,southwest,north,northeast and coastal regions of China were collected.Analysis of soil properties of different saline-alkali soils by physical and chemical properties testing,and high-throughput sequencing technology was used to analyze the microbial community diversity of saline-alkali soils in different regions.Finally,the environmental driving factors of microbial community distribution in different regions of saline-alkali soil in China were analyzed by canonical correspondence analysis method,which provided a reference for the study of the ecological functions and soil improvement of saline-alkali soils.At the same time,the study also used culture methods to isolate known and unknown bacterial strains from saline-alkaline soil samples in Northeast China,and provided guidance for the mining of saline-alkaline soil microbial resources.The main conclusions of this study are as follows:?1?The results of physicochemical properties of different types of saline-alkali soils in 20 different regions showed that the same types of saline-alkaline soils in the same area were similar in physical and chemical properties,while different types of saline-alkali soils in different regions had significantly different soil anion contents.The northeast soda saline-alkali soil,the saline-alkaline soil in the North China Plain,the western desert saline-alkali soil and the coastal saline-alkali soil are dominated by HCO₃^-/CO₃^2-?SO₄^2-?SO₄^2-/Cl and Cl^-,respectively.?2?High-throughput sequencing of fungal ITS sequences from 19 different regions and types of saline-alkaline soil samples with soil physicochemical properties showed that the species richness and diversity of fungal communities in the saline-alkaline soil samples in western China were low and the fungal community of coastal saline-alkaline soil samples has higher species richness and diversity.In 19samples,a total of 5 phylums,29 classes,100 orders,230 families,447 genera were detected.The five phylums are Ascomycota?Basidiomycota?Zygomycota?Glomeromycota and Chytridiomycota.Ascomycota was most dominant in 16 saline soils,and basidiomycota was most dominant in 3 samples.The differences in fungal community structure in different saline-alkaline soil samples were significant.The weighted unifrac analysis based on OTUs found that the samples in coastal areas had obvious clustering relationships,while other regions did not show regular clustering relationships.The results of canonical correspondence analysis?CCA?found that the physical and chemical properties of the assay were not environmental factors driving the differential distribution of fungal communities noted in this study.?3?High-throughput sequencing of 16S rDNA sequences of archaeal bacteria in32 different saline-alkaline soil samples showed that the dominant archaeal communities of different saline-alkali soils were Euryarchaeota,Thaumarchaeotaand,Woesearchaeota_.DHVEG-6,Bathyarchaeota and Nanohaloarchaeota.The weighted unifrac analysis based on OTUs showed that the archaeal community of 32saline-alkaline soil samples formed two major branches.Variance partitioning canonical correspondence analysis?VPA?showed that soil factors?contribution rate52.15%?were more likely to affect and promote the succession of saline-alkaline soil archaeal community structure than other environmental factors?contribution rate20.57%?.CCA analysis further proved that the types and concentrations of soil anions such as HCO₃^-?Cl^-?SO₄^2-were the main driving factors for the succession and migration of archaeal community structure.?4?High-throughput sequencing results of bacterial 16S rDNA sequences from32 samples of saline-alkali soil showed that the bacterial community composition of different saline-alkali soil was diverse,and Proteobacteria,Actinobacteria,Firmicutes,Bacteroidetes,and Cyanobacteria were the dominant groups.VPA analysis showed that soil factors?contribution rate 51.04%?were more likely to affect and promote the succession of bacterial community structure in saline-alkali soil than other environmental factors?contribution rate 21.24%?.The CCA analysis further proved that the soil anion types and concentrations of HCO₃^-?CO₃^-?Cl^-?SO₄^2-?NO₃^-?PO₄^3-drive the succession and migration of bacterial community structure.Therefore,soil anion is the main driving factor for the formation of prokaryotic microbial community structure in different saline-alkaline soils in China.?5?Gammaproteobacteria,Alphaproteobacteria,Alphaproteobacteria,Bacilli,Actinobacteria and Cytophagia are the dominant bacteria in different soil bacterial communities.It accounts for 40.8%-89.5%of total bacteria,but it is rich in a large but it was rich in new species OTUs which could not be annotated,accounting for 18.6%to 38.8%of the total bacteria.The results indicate that there are a lot of new microbial species in saline-alkaline soils in China.In this paper,taking the northeast soda saline-alkali soil as an example,262 strains of bacteria were isolated and most belonged to the above six bacterial classes.The results of 16S rRNA sequencing of bacterial isolates showed that 47 bacterial strains were potential new species,and most of them were Gammaproteobacteria.