| Ammonia oxidation process as the first step of nitrification process is also a key limiting step,performed by both ammonia-oxidizing archaea(AOA)and ammoniaoxidizing bacteria(AOB).The discovery of Ammonia-Oxidizing Archaea(AOA)improved the understanding that the ammonia oxidation was only performed by Ammonia-Oxidizing Bacteria(AOB)in the past.Black soil area in Northeast China is the only three black soil area in the world and has abundant wetland types.Wetland as an important microbial nitrogen cycle medium has a strong edge effect,and has important research value has important research value.It is of great ecological significance to explore the distribution of two ammonia-oxidizing microbes with the same ecological functional in different habitats.This paper is based on two typicals northeast cold marsh,the acid soil of SanJiang national reserve wetland and the weak alkaline soil of ZhaLong national reserve wetland as the research object,combining the physical and chemical analysis with molecular biological methods to explore the activity,abundance,community structure and the influence of environmental factors of the AOA and AOB in two typical wetlands.Aiming provide a theoretical basis for the study of the ecological niche and the ecological function of ammonia-oxidizing microbes in complex wetland environment.In this study the results shows that the difference of plant do not affect the potential ammonia oxidation acitivity(PAO)and the abundance of ammonia-oxidizing microbes,while the AOB plays an important role in sedge plant.The pH of the soil can significantly affect AOA's PAO(p < 0.01);In the two wetlands and abundance of AOA and PAO(AOA and AOB)show significant positive correlation(p < 0.05),while with PAO(AOA)there is no correlation,suggests that the abundance of functional genes does not represent the strength of function expression.The structure of the AOA and AOB populations in different properties wetland have obviously difference.The richness and diversity of AOA in weak alkaline wetland is significantly higher than that of acidic wetland,while there is no significant difference in AOB populations.In the sample plot,the AOA population structure is dominated by Nitrososphaera cluster,the AOB population structure is mainly on Nitrosomonadales.Nitrososphaera subcluster1 is abundant exist in two sampling periods of growing season and non-growing season of SanJiang wetland which the proportion is 99.78% and 90.11% suggesting that it prefer an acid environment,while Nitrososphaera subcluster1.2 only appear in ZhaLong wetland at two seasons implies that it may prefer a weak alkaline environment.As the growing season turn to non-growing season,the richness and diversity of ammonia-oxidizing microbes population in two wetlands are decreased.In the AOA community of ZhaLong weland,the share of Nitrosospumilus cluster whose prefer oligotrophic environment is fall from 14.27% to 4.12% with the rise of the concentration of NH4+,the acidophilic Nitrosotalea cluster in the sanjiang wetland was greatly enhanced from 0.002% to 9.44% by the increase of pH in nongrowing soil.For AOB,the proportion of Proteobacteria of ZhaLong wetland from 31.36% up to 93.16% in the non-growing season to the dominant position,while the population composition of Sanjiang wetland in the growing season and non growth season varied little.In the Genus level,from the growing season to the non-growing season,the proportion of Nitrosospira cluster from Zha Long wetland is greatly increased from 29.51% to 89.36% in non-growing season.However,the Nitrosospira cluster in SanJiang wetland fall from 16.77% to 34.71%.Nitrosovibrio is the genus only from SanJiang wetland.These results provide a theoretical basis for revealing the distribution characteristics of ammonia-oxidizing microbes and their ecological functions in different wetland ecosystems. |
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