| On the condition of extreme environment, the relationship between microbial community succession and climate evolution is an international frontier. Permafrost microorganisms are particularly sensitive to environmental changes, thus, it is significant for the study of the distribution of permafrost microorganisms, genetic change and natural selection to evaluate past climate changes as well as the influence of biological and human activities on the Earth's environment.In order to understand spatial and temporal variations of soil microorganism in the headwaters of the Urumqi river, soil from different altitudes and different depths has been sampled. Here, fluorescence microscopy counting techniques, few nutrients of cultivation techniques,16S rDNA gene cloning, molecular markers-deformation gradient gel electrophoresis (DGGE), restriction fragment length polymorphism (T-RFLP), were used to reveal the microbial community structure and diversity. Soil physical, chemical and other environmental variables are mensured as well. The results obtained here were summarized as follows:1,In the samples which representing different age, the cultured bacterial amount have a significant, positive correlation with age, soil moisture content, total C, total N concentrations, and have a significant, negative correlation with pH value. It suggested that cultured bacterial amount and the environment are closely linked. Moreover, as age increasd, the cultured bacterial amount in the ratio of total cell number are decreasing. In the samples which at different altitudes, the correlation between the cultured bacterial amount and soil moisture content, total C, total N concentrations, pH value are not as well as the samples at different depths. We found that the altitude does not the determining factor affect the number of bacteria, but different vegetation types have some decisive on the growth of bacteria:monocot herb> arbor plants> dicotyledonous herbs.2,Cultivation-dependent approaches showed that the 31 strains at different depths belong to following group:Firmicutes,Actinobacteria,α-Protebacteria,β-Protebacteria and y-Protebacteria. Actinobacteria have a significant, negative correlation withα-,β-,γ-Protebacteria; Firmicutes have a significant, positive correlation with P-Protebacteria; y-Protebacteria have a significant, positive correlation with pH, and have a significant, negative correlation with the cultured bacterial amount. The 23 strains at different altitudes belong to following group: Firmicutes,Actinobacteria,α-Protebacteria,β-Protebacteria,γ-Protebacteria and Bacteroidetes.α-Protebacteria have a significant, negative correlation withβ-Protebacteria, and have a significant, positive correlation with Firmicutes; Actinobacteria have a significant, positive correlation with depths. It suggested that the types and diversity of bacteria not only affected by environmental, but also the result of the interaction between them.98.60% pigmented colonie was observed in the samples at different depths, the deep sample is smaller than the surface sample; 47.06% pigmented colonie was observed in the samples at different altitudes, as altitude increasd, the ratio is reduced. Further analysis found that many of the strains isolated were functional bacteria, they have great value at purifing the environmental of the headwaters of the Urumqi river and constructing ecological.3,DGGE analysis of bacteria showed that the 23 representative bacterial bands at different depths belong to following group:Actinobacteria,α-Protebacteria,β-Protebacteria,δ-proteobacteria,Nitrospira,Acidobacteria and Gemmatimonadete; the 30 representative bacterial bands at different altitudes belong to following group: Actinobacteria,α-Protebacteria,β-Protebacteria,δ-proteobacteria,Nitrospira,Acidobacteria,Gemmatimonadete,Firmicutes,Thermodesulfobacteria,Chloroflexi and Bacteroidetes. Analysis of the bacterial community structure diversity (shannon index) and richness showed that the difference of bacterial diversity at different depths and at different altitudes is small. However, it should point out that, DGGE method can be detected more groups of bacteria, but some can resume training were not detected out, and thus need to combined molecular methods with the traditional culture technique to more fully and more comprehensively study soil microorganisms.4,DGGE analysis of archaea showed that the 21 representative arehaeal bands at different depths belong to following kind:Caldisphaera,Pyrolobus,Methanolinea,Thermogymnomonas,Methanosphaerula and Methanocella; the 17 representative arehaeal bands at different altitudes belong to following kind:Caldisphaera,Methanolinea,Thermogymnomonas and Methanosphaerula. Analysis of the arehaeal community structure diversity (shannon index) showed that shannon index is between 0.8 to 1.0 in the samples at different depths, the diversity increase with depth increasing; shannon index is between 0.5 to 1.1 in the samples at different altitudes, the diversity increase with altitude increasing.Above all, these studies have shown that the number of microbes, composition and distribution in the samples at different depths and at different altitudes are very different, and to some extent, were interrelated with the indicators of environment and climate and spatial and temporal changes. They can provide scientific reference to deduce the evolution law of climate and environment in the headwaters of the Urumqi river, and to control the construction of local ecological environment. |
