Soil Microbial Diversity In Vegetation Of Different Restoration Years Of Mu Us Sandy Land And The Identification Of Two Novel Species

Mu Us Sandy land is one of the areas with severe desertification in China.Over the years,the local government has implemented a series of huge projects of ecological restoration and vegetation construction,and achieved objective results.In order to understand the distribution and variation of microbial community structure under the Mu Us Sandy land vegetation,three different types of typical vegetation rhizosphere soils and untreated sandy lands planted in 1960,1985,and 1995 were selected as research objects.Based on the components of soil ecosystems:vegetation,soil,and microbial communities,soil microbial community structure and soil physicochemical properties of different vegetation restoration types were studied by dilution plate count method and high-throughput sequencing technology to explore the rhizosphere soils of different types of vegetation.The differences in the distribution of microbial communities between the rhizosphere soil and the quicksand,and the main factors causing the differences were analyzed.This reveals the effect of vegetation restoration on the diversity of microbial species and communities and the interaction between above-ground and below-ground biological communities.The main results of this study are as follows:Based on traditional separation techniques,the study on the distribution of bacteria,actinomycetes,and fungi in the vegetation rhizosphere soils of different restoration years revealed that the vegetation recovery can be significantly increased compared with quicksand.The number of microorganisms in the soil;and the number of various types of microorganisms present bacteria>actinomyces>fungi.The effect of different types of vegetation restoration on the number distribution of microorganisms was shrub>grass>arbor>quicksand,and the microbial biomass of shrubs was significantly higher than that of the other two vegetations.The effect of different vertical depths on the distribution of microorganisms showed a decreasing trend with the increase of soil depth.In particular,the number of microorganisms in 0-5 cm was much larger than that in low levels.The number of vegetation microbes in different restoration years was affected by the type of vegetation.The changes in the number of different stratified microorganisms and the species types and relative contents of the dominant stratigraphic species in each group indicated that the abundance and diversity of the soil microorganisms in the shrub-grown roots were high.Based on high-throughput sequencing analysis,compared with quicksand,vegetation restoration had a positive effect on the abundance and diversity of soil bacterial community structure.The shrubs showed higher bacterial community abundance,evenness and diversity,but the difference in bacterial community abundance between different vegetation types was not significant.The vertical depth has a great influence on the diversity of soil bacteria.With the increase of depth,the abundance decreases gradually,while the diversity is affected by the type of vegetation and the growth period,but the overall performance is 0-5 cm>10-20 cm>5-10 cm>20-30 cm.The growth period had no significant effect on the bacterial community abundance,but the diversity showed an increase with the increase of vegetation growth period,but the difference was not significant.Bacterial community at the gate classification level in all samples,the dominant relative bacteria abundance was 90% in the case of Proteobacteria、Actinobacteria、Firmicutes、Bacteroidetes and Acidobacteria.The relative contents of the dominant flora in the vegetation recovery soil and the quicksand were different.The highest concentration of bacteria in the quicksand was the Firmicutes,and the vegetation restoration soil was Proteobacteria.Cluster analysis of different vegetation restorations at the level of phylums revealed that the distribution of bacteria in shrubs and trees was higher.The cluster analysis of different restoration vegetations at the genus classification level found that the types of bacterial species in the quicksand were relatively single,while the bacterial species in the vegetation restoration were abundant and diverse,and the bacterial abundance and diversity of the shrubs were significantly higher than those of the trees and vegetation.Soil urease,alkaline phosphatase,p H,organic carbon and organic matter are the main physical and chemical factors that affect the abundance and diversity of soil bacterial communities,and there is a significant negative correlation between p H and bacterial diversity.In summary,it can be concluded that shrubs are the dominant species in the area.Through the isolation and identification of microorganisms from the soil of Mu Us Sandy Land,126 strains of culturable bacteria were isolated.The analysis of strain 16S rRNA gene sequences revealed that all strains were divided into 4 bacterial gates and 28 genera.Based on the analysis of phenotype,physiological and biochemical characteristics,chemical taxonomy,genotype and phylogeny,strain YL28-9~T was identified as a new species of Pedobacter and named Pedobacter yulinensis sp.nov.