Departamento Sistemas Físicos, Químicos y Naturales, Universidad Pablo de Olavide, Sevilla, Spain.
FEMS Microbiol Ecol. 2013 Aug;85(2):273-82. doi: 10.1111/1574-6941.12119. Epub 2013 Apr 18.
An integrated perspective of the most important factors driving the abundance of ammonia-oxidizing bacteria (AOB) and archaea (AOA) in natural ecosystems is lacking, especially in drylands. We evaluated how different climatic, abiotic, and nutrient-related factors determine AOA and AOB abundance in bare and vegetated microsites from grasslands throughout the Mediterranean Basin. We found a strong negative relationship between the abundance of AOA genes and soil fertility (availability of C, N, and P). Aridity and other abiotic factors (pH, sand content, and electrical conductivity) were more important than soil fertility in modulating the AOA/AOB ratio. AOB were more abundant under vegetated microsites, while AOA, highly resistant to stressful conditions, were more abundant in bare ground areas. These results suggest that AOA may carry out nitrification in less fertile microsites, while AOB predominate under more fertile conditions. Our results indicate that the influence of aridity and pH on the relative dominance of AOA and AOB genes is ultimately determined by local-scale environmental changes promoted by perennial vegetation. Thus, in spatially heterogeneous ecosystems such as drylands, there is a mutual exclusion and niche division between these microorganisms, suggesting that they may be functionally complementary.
缺乏对驱动自然生态系统中氨氧化细菌 (AOB) 和古菌 (AOA) 丰度的最重要因素的综合观点，特别是在干旱地区。我们评估了不同的气候、非生物和与营养有关的因素如何决定地中海盆地整个草原的裸地和植被微生境中 AOA 和 AOB 的丰度。我们发现 AOA 基因丰度与土壤肥力（C、N 和 P 的可利用性）呈强烈负相关。干旱和其他非生物因素（pH 值、沙含量和电导率）比土壤肥力更能调节 AOA/AOB 比。在植被微生境下 AOB 更为丰富，而对胁迫条件具有高度抗性的 AOA 在裸地区域更为丰富。这些结果表明，AOA 可能在肥力较低的微生境中进行硝化作用，而 AOB 在更肥沃的条件下占优势。我们的结果表明，干旱和 pH 值对 AOA 和 AOB 基因相对优势的影响最终取决于多年生植被促进的局部尺度环境变化。因此，在像旱地这样空间异质的生态系统中，这些微生物之间存在相互排斥和生态位划分，表明它们可能在功能上是互补的。
