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探讨土壤微生物指标的变化规律,用于揭示其在岩溶土壤碳循环中的指示意义.以桂林岩溶试验场洼地、坡地和垭口这3种岩溶地貌形态下的剖面(0~10、10~20、20~30cm)土壤为研究对象,采用聚合酶链式反应-变性梯度凝胶电泳(PCRDGGE)和荧光定量PCR相结合的方法,分析这个典型岩溶土壤剖面中的微生物多样性和丰度变化.数据显示,16S rRNA最高丰度出现在洼地,为1.32×1011拷贝·g-1,而18S rRNA最高丰度出现在垭口,为1.12×1010拷贝·g-1;洼地和垭口剖面的16S rRNA丰度随着深度的增加而降低,3种岩溶地貌形态的18S rRNA丰度均随着剖面深度的增加而降低,与土壤有机碳质量分数的变化趋势一致.但是,在3种岩溶地貌形态中,3个16S rRNA和6个18S rRNA的多样性指数均随土壤剖面深度的增加而增大.由于16S rRNA和18S rRNA的多样性与丰度和土壤有机碳之间总体上表现出相反的变化趋势,说明微生物丰度指标在土壤碳循环中的指示意义比微生物多样性指数更重要.
The change regularity of soil microbial index was discussed to reveal its significance in the carbon cycle of karst soil.Under the three karst geomorphological forms of depression, slope and pass in Guilin Karst Experimental Site, the profiles (0-10, 10-20, 20 ~ 30cm) soils, the changes of microbial diversity and abundance in this typical karst soil profile were analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCRDGGE) combined with real-time quantitative PCR The highest abundance of 16S rRNA was 1.32 × 1011 copies · g-1 in the depression, while the highest abundance of 18S rRNA was 1.12 × 1010 copies · g-1 in the depression. The 16S rRNA abundance in the depression and the pass With the increase of depth, the 18S rRNA abundance of three karst landforms decreased with the increase of profile depth, which was consistent with the change trend of soil organic carbon mass fraction.However, among the three karst topography, 3 The diversity index of 16S rRNA and 6 18S rRNA all increased with the increase of soil profile depth.Because the diversity and abundance of 16S rRNA and 18S rRNA showed opposite trend with soil organic carbon, Explain microbial abundance Marked on the soil carbon cycle is more important than an indication of the significance of microbial diversity index.