Spatial And Temporal Distribution Patterns Of Ammonia-oxidizing Microorganisms In Rhizosphere Of Constructive Plants In Ebinur Wetland And Isolation And Identification Of Myxobacteria

Ebinur Wetland has become a climate regulation hub in the Ebinur Lake Basin in northern Xinjiang because of its unique wetland desert ecosystem.Ammonia oxidation is the primary reaction step of nitrification in nitrogen cycle and the speed-limiting step.Ammonia monooxygenase gene(amoA)in this process is often used as a molecular marker to study ammonia-oxidizing microorganisms because of its high conservativeness,which can be used to analyze the genetic diversity of ammonia-oxidizing microorganisms.The purpose of this study was to reveal the differences of AOA community structure between rhizosphere and non-rhizosphere soils of halophytes in different seasons,and to provide a theoretical basis for further study of the relationship between microorganisms and salt tolerance in rhizosphere soil of halophytes.In addition,the myxobacteria in rhizosphere and non-rhizosphere soil of Salicornia in three seasons were isolated,purified and identified,in order to provide an experimental basis for further study of myxobacteria.The rhizosphere and non-rhizosphere soil of Halocnemum strobilaceum,Salicornia,Karelinia caspica and Reed in three seasons of spring,summer and autumn in Ebinur Lake wetland was collected in this study.Study on the environmental condition of rhizosphere soil of different plants in different seasons by measuring the physical and chemical properties of soil.The diversity and community structure of ammonia-oxidizing archaea(AOA)in rhizosphere and non-rhizosphere soils of Halocnemum strobilaceum,Salicornia,Karelinia caspica and Reed in different seasons(spring,summer and autumn)were studied by high-throughput sequencing technique using ammonia monooxygenase gene(amoA)as a molecular marker.In addition,the correlation among AOA diversity,community structure and soil environmental factors was explored by RDA analysis.At the same time,myxobacteria in rhizosphere and non-rhizosphere soil of Salicornia in spring,summer and autumn were isolated,purified and identified.The results of soil physical and chemical indexes showed that the pH of rhizosphere and non-rhizosphere soil of different plants varied in different seasons,but the difference was not significant.The pH value ranged from 7.42 to 8.18,all of which were alkaline soil.In spring,summer and autumn,the soil water moisture(SM)in rhizosphere and non-rhizosphere of four plants were RR > SR > SN > RN > HR > HN > KN > KR,RR > SN > SR > RN > KN > KR > HR > HN,SN > SR > KR > RN > HN > RR > KN.The electrical conductivity(EC)of rhizosphere and non-rhizosphere soil of different plants varied in different seasons.The electrical conductivity of soil varied greatly in different plant communities,while the seasonal difference was relatively small.Soil Fertility Indicators showed that the soil fertility level of Ebinur Lake wetland was relatively poor,and the fertility level of different plant rhizosphere and non-rhizosphere soil showed differences.On the whole,the soil quality of four plant communities in Ebinur Lake wetland showed the following patterns: Reed>Karelinia caspica>Salicornia>Halocnemum strobilaceum;summer > spring > autumn.The results of diversity and community structure showed that the diversity of ammonia-oxidizing archaea community in rhizosphere soil of Reed was higher than that in non-rhizosphere soil in spring and lower than that in non-rhizosphere soil in summer and autumn;In summer,the diversity of rhizosphere soil was higher than that of non-rhizosphere soil of Karelinia caspica,and lower than that of non-rhizosphere soil in spring and autumn.The diversity of rhizosphere soil of Halocnemum strobilaceum in three seasons was lower than that of non-rhizosphere soil.The diversity of rhizosphere soil of Salicornia was higher than that of non-rhizosphere soil in three seasons.In addition,the relative abundance of AOA in rhizosphere soil of four plants was higher than that in non-rhizosphere soil.AOA community in all soil samples was mainly concentrated in Crenarchaeota and Thaumarchaeota,and the proportion of AOA community in different soil samples was different.RDA results showed that the community characteristics of AOA of different plants in different seasons were influenced by many environmental factors.In this study,salinity(EC),soil water moisture(SM),pH and soil organic matter(SOM)were important factors affecting the differentiation of AOA communities.Morphological observation of Myxobacteria showed that black fruiting bodies were produced on the culture medium,and the degradation of filter paper and the depression of the culture medium were also observed.Myxobacteria producing black fruiting bodies were preliminarily classified into the genus Leptocystis.