小叶锦鸡儿固沙林土壤G^+与G^-细菌碳代谢功能多样性

Functional diversity of carbon sources metabolism of soil G^+ and G^- bacteria in sand-fixing Caragana microphylla plantations

为探讨科尔沁沙地流动沙丘上建立小叶锦鸡儿固沙植被后,土壤微生物群落中革兰氏阴性菌和革兰氏阳性菌代谢功能的变化规律,采用Biolog-GN2和GP2微平板检测法,研究了9、16、26年生人工群落以及流动沙丘和天然小叶锦鸡儿群落土壤革兰氏阴性和革兰氏阳性菌碳源代谢的多样性变化特征。结果表明,流动沙丘建立小叶锦鸡儿固沙植被后,土壤革兰氏阴性菌多样性表现为持续缓慢增加的趋势,0～26年生群落Shannon指数由3.85逐渐增加到4.17,均匀度指数由0.85增加到0.94;而革兰氏阳性菌则表现为先显著降低,后逐渐增加的趋势。随着固沙群落年龄的增长,土壤微生物代谢糖类、羧酸类、双亲化合物类、聚合物类、胺/酰胺类和氨基酸类等碳源种类逐渐增加。26年生小叶锦鸡儿人工群落土壤革兰氏阴性和革兰氏阳性菌的碳源代谢模式已逐渐接近天然群落。

To understand the variations of the metabolic function of soil G＋ and G- bacteria on the mobile sand dune of Horqin sandy land after the establishment of sand-fixing Caragana microphylla plantation, Biolog-GN2 and GP2 microplate tests were conducted to study the functional diversity of carbon sources metabolism of soil G＋ and G- bacteria in the 9-, 16-, and 26-year-old C. microphylla plantations, with the mobile sand dune and natural C. microphylla community as the controls. The establishment of C. microphylla plantation on the mobile sand dune resulted in a gradual increase of the functional diversity of carbon sources metabolism of soil G- bacteria, and their Shannon index and evenness index for the 0- to 26-year-old plantations increased from 3.85 to 4.17 and from 0.85 to 0.94, respectively. As for G＋ bacteria, their Shannon index and evenness index had a significant decrease first （P0.05）, and then increased gradually with the increasing age of C. microphylla plantation. The carbon source types （carbohydrates, carboxylic carbons, amphiphilic compounds, polymers, amines, and amino acids） metabolized by soil G＋ and G- bacteria increased with plantation age. The utilization patterns of carbon sources by the soil G＋ and G- bacteria in 26-year-old C. microphylla plantation were similar to that in natural C. microphylla community.