Studies On Changes And Regulation Of Soil Microorganism In The Process Of Reclamation In Jungar Coal Field Of Inner Mongolia

With the construction and development of opencast coal mine, open-pit mining will impose increasingly grave harm on land resources and ecological environment in mining areas, ecological restoration of mining waste lands is an urgent task to face. The aim of this article is to understand the basic composition and variation of soil microorganisms in the process of reclamation in mine areas of Jungar Coal Field, Ordos Plateau, Inner Mongolia, investigate the relationship between different restoration stages of vegetation and the changes of soil microorganisms in reclamation area. By measuring the soil microorganism amount, soil biological activity and soil physical and chemical properties, the changes of soil in different reclamation years could be reflect directly or indirectly. The community diversity and changes of soil microorganisms with different reclamation years were analyzed by some conventional analytical methods and PCR-DGGE. In this paper, the main conclusions were as follows:(1) In regard to the changes of soil microorganism amount, in the whole, all kinds of soil microbes showed significant differences with the changes of reclamation years. The number of Bacteria was the largest and the Fungi was the least, which accounted for 78.77%-99.84% and 0.00%-0.02% respectively. Self-nitrogen-fixing bacteria accounted for 0.04%-20.95% while Actinomycetes accounted for 0.01%-0.89%. The number of various types of soil microorganisms were significantly higher than that of control CK1.(2) In regard to the soil biological activity, soil microbial biomass carbon changed with reclamation years and different types showed different variation. Analyses of variance showed that soil microbial biomass carbon with different reclamation years in two different vegetation configuration modes reached significant difference. While variation of soil enzyme activities (Urease,Invertase,Catalase,Polyphenoloxidase,Dehydrogenase) were also different. There was no direct relationship between variation and reclamation years. Our results implied that the factors affecting soil biological activity was complex.(3) In regard to the changes in soil nutrient with different reclamation years, total carbon and total nitrogen had a similar variation. When analyzed the content of total phosphorus and total potassium, the content of two vegetation configuration modes were higher than the control CK1. Soil with different reclamation years had higher nitrogen, phosphorus and lower potassium. The characteristics of the soil was consistent with that of the study area. Nutrient content and reclamation years did not show regularity of change.(4) Protocols in molecular biology can be applied in the study of mine soil successfully. Total microbial DNA extracted from the soil samples could fit the further molecular biological experiment. PCR amplification products of 16SrDNA target gene (V6-V8 region) from bacterial samples and 18SrDNA target gene from fungal samples could fully meet the requirements of DGGE experiment.(5) Significant differences in communities diversity of soil bacteria and fungi can be reflected by the difference in soil bacterial and fungal DGGE gel electrophoresis. Simpson and Shannon diversity index showed the diversity of different reclamation years variation of a more consistent, however, regardless of the type of ground and plant grass bushes and trees artificial communities, or a legume-grass forage types of communities, with the increasing reclamation years, the diversity of soil bacteria and fungi do not had differences and changes in regular patterns. Compared with CK1 and CK2, the diversity of different plots with different reclamation years were significantly higher.(6) PCR-DGGE can be applied in the study of soil microorganisms successfully. Our study suggested that soil bacteria involved in Jungar Coal Field with different reclamation years can be classified in 7 bacterial populations: Firmicutes,Bacteroidetes,Actinobacteria,Proteobacteria [Alphaproteobacteria,Betaproteobacteria,Gammaproteobacteria,Deltaproteobacteria],Acidobacteria,Gemmatimonadetes and Unclassified bacteria. Among these,Actinobacteria was the most important bacterial population. Soil fungi involved can be classified in 4 fungal populations: Ascomycota,Glomeromycota,Basidiomycota and Unclassified fungi. Among these,Ascomycota was the most important fungal population.Meanwhile, 69 soil bacterial sequences involved in soil with different reclamation years, 43 bacteria can not be cultured, which accounted for 62.3%. 37 soil fungal sequences involved in soil with different reclamation years, 10 fungi could not be cultured, which accounted for 27.0%. All these results well demonstrated that application of PCR-DGGE technology can reveal more comprehensive information on microorganisms in soil ecosystem.