Characteristics Of Sulfur Cycle Metabolic Pathways And Microbial Community Structure Of Sulfur Cycle Function In Several Major Soils In China

Sulfur element is one of the essential nutrients of living organisms,and it is the main constituent of life substances,and plays an important role in the process of life metabolism.Land use patterns and soil types are important human and natural factors affecting soil nutrient cycling,and their effects on soil sulfur cycling and functional microbial communities are of great significance.The purpose of this study was to study the effects of different land use types and soil types on the characteristics of soil sulfur cycle metabolism pathway and the structure of sulfur functional microbial community.Rice field,dry land,forest land and fallow land developed with the same soil type were selected as the research object.Metagenomic bioinformatics technology was used to explore the composition of functional microbial community related to sulfur cycle in soil of different land uses,and to analyze the characteristics of soil sulfur cycle pathway and related functional microbial community structure in different land uses.Secondly,black soil,aquic soil,yellow soil,purple soil and red soil under the same land use were selected as the research objects.Macrogenomic sequencing technology was used to analyze the abundance and community structure composition of sulfur-cycling microorganisms in different soil types,to explore the influence of soil types on the abundance and community structure composition of soil sulfur-cycling microorganisms,and to further analyze the influence of natural factors on soil sulfur cycling.The main findings are as follows:There were similar characteristics of sulfur cycle pathway in paddy field,upland,forest land and fallow farmland,that is,organic matter transformation pathway is the most frequently detected pathway of microbial functional genes,with an average of 44201 functional genes detected per million annotated microbial sequences,and sulfur disproportionation pathway is the least frequently detected pathway of microbial functional genes,with an average of 163 functional genes detected per million annotated microbial sequences.In this study,due to the change of land use patterns,there are significant differences in physical and chemical properties among samples.Under different land use patterns,the abundance of soil sulfur cycle function genes is generally affected by soil physical and chemical properties,among which p H and organic carbon have the greatest influence.Different land use patterns will also affect the functional microbial community structure involved in soil sulfur cycle,but in this study,the functional microbial community structure involved in soil sulfur cycle in woodland and fallow land is similar.On the level of classification,the microbial community structure of soil participating in sulfur cycle under different land use patterns is similar,and the dominant bacteria belong to Proteobacteria(14.9%～56.74%),Acidobacteria(10.65%～20.41%)and Chloroflexi.2.66%～19.21%),Actinobacteria(4.06%～32.38%)and Nitrospirae(0.068%～6.53%).There are Actinobacteria(4.06%～32.38%)with relatively high abundance under the development of red soil.However,there are differences in species classification of microorganisms leading sulfur cycle in different land use patterns,and this difference is most obvious in paddy soil and other three land use patterns,such as paddy soil,Among the dominant groups of functional microorganisms involved in sulfur cycle,the top three microbial strains are Acidobacteria bacterium 、 Betaproteobacteria bacterium and Deltaproteobacteria bacterium.However,Actinobacteria bacterium,Chloroflexi bacterium and Acido Bacterium are the main microbial strains for sulfur transformation in dry farmland,forest and fallow farmland.Different soil types(black soil,fluvo-aquic soil,yellow soil,purple soil and red soil)also have the similar characteristics of sulfur cycle pathway,that is,organic matter transformation pathway is the most frequently detected pathway for microbial functional genes,with an average of 44 233 functional genes detected per million annotated microbial sequences,and sulfur disproportionation pathway is the least frequently detected pathway for microbial functional genes,with an average of 169 functional genes detected per million annotated microbial sequences,indicating that the change of soil types has no effect on soil.There are significant differences in the abundance of functional genes involved in sulfur cycle under different soil types.p H,soil nutrients and water are important factors affecting the abundance of functional genes involved in sulfur cycle.The functional groups of soil sulfur cycle in dry farmland,forest land and fallow farmland developed by five soil types are obviously separated,but the functional groups of soil sulfur cycle in paddy soil developed by different soil types are more similar.In paddy soil,the proportion of microorganisms involved in sulfur cycle in paddy soil with different soil types is not much different,and Proteobacteria,Actinobacteria,Acidobacteria and Chloroflexi are the main microorganisms,with the average abundance ratios of 50.14%,7.96%,11.22% and11.22% respectively.Under the other three land use patterns,Actinobacteria with high relative abundance were found in the soil developed from red soil,indicating that specific microbial groups are generally distributed in their preferred soil types,that is,the ecological attributes of these specific sulfur cycling functional groups are more sensitive to the environmental conditions of some soil types.Further analysis showed that there was no significant difference in the functional bacteria involved in sulfur cycling metabolism in different soil types,and Acidobacteria bacterium Betaproteobacteria bacterium and so on were the main ones.In other samples,Actinobacteria bacterium,Acidobacteria bacterium and Betaproteobacteria bacterium are the most abundant functional bacteria for sulfur cycle.Based on the results of this study,it is found that both land use patterns and soil types will affect the characteristics of soil sulfur cycle metabolism pathway and sulfur transformation functional microorganisms,the effect of land use on soil sulfur cycling microbial community was greater than that of soil type.Based on this,the following conclusions are drawn:(1)There were similar characteristics of sulfur cycle pathway in paddy field,dry farmland,woodland and fallow farmland.The sulfur cycling pathway and microbial community structure in paddy soil are affected by p H and soil nutrients,and more by water content in dry farmland,woodland and fallow farmland.(2)There is no significant difference in the level of microorganism leading sulfur cycle under different land use patterns,but there are differences between paddy soil and other three land use patterns at the level of species;(3)Different soil types(black soil,fluvo-aquic soil,yellow soil,purple soil and red soil)also have the similar characteristics of sulfur cycle pathway.The functional groups of sulfur cycling in upland farmland,woodland and fallow farmland with different soil types are obviously separated,but the functional groups of sulfur cycling in paddy soil are more similar.(4)In paddy soil,there is no significant difference in microbial species involved in sulfur cycle in paddy soil with different soil types,and there is no significant difference in species level classification.Under the other three land use patterns,Actinobacillus was found in the soil developed from red soil,while Actinobacteria bacterium and Acidobacteria bacterium were the dominant functional bacteria for sulfur cycle in other samples.