Department of Biology-Microbial Ecology, Ekologihuset, Lund, Sweden.
Appl Environ Microbiol. 2012 Aug;78(16):5906-11. doi: 10.1128/AEM.01476-12. Epub 2012 Jun 15.
Soil pH is one of the most influential factors for the composition of bacterial and fungal communities, but the influence of soil pH on the distribution and composition of soil archaeal communities has yet to be systematically addressed. The primary aim of this study was to determine how total archaeal abundance (quantitative PCR [qPCR]-based estimates of 16S rRNA gene copy numbers) is related to soil pH across a pH gradient (pH 4.0 to 8.3). Secondarily, we wanted to assess how archaeal abundance related to bacterial and fungal growth rates across the same pH gradient. We identified two distinct and opposite effects of pH on the archaeal abundance. In the lowest pH range (pH 4.0 to 4.7), the abundance of archaea did not seem to correspond to pH. Above this pH range, there was a sharp, almost 4-fold decrease in archaeal abundance, reaching a minimum at pH 5.1 to 5.2. The low abundance of archaeal 16S rRNA gene copy numbers at this pH range then sharply increased almost 150-fold with pH, resulting in an increase in the ratio between archaeal and bacterial copy numbers from a minimum of 0.002 to more than 0.07 at pH 8. The nonuniform archaeal response to pH could reflect variation in the archaeal community composition along the gradient, with some archaea adapted to acidic conditions and others to neutral to slightly alkaline conditions. This suggestion is reinforced by observations of contrasting outcomes of the (competitive) interactions between archaea, bacteria, and fungi toward the lower and higher ends of the examined pH gradient.
土壤 pH 值是影响细菌和真菌群落组成的最主要因素之一，但土壤 pH 值对土壤古菌群落分布和组成的影响尚未得到系统研究。本研究的主要目的是确定在 pH 梯度（pH 值 4.0 至 8.3）范围内，总古菌丰度（基于 16S rRNA 基因拷贝数的定量 PCR [qPCR] 估计值）与 pH 值的关系。其次，我们想评估古菌丰度与同一 pH 梯度内细菌和真菌生长速率的关系。我们发现 pH 值对古菌丰度有两种截然不同的相反影响。在最低 pH 值范围（pH 值 4.0 至 4.7），古菌丰度似乎与 pH 值无关。在这个 pH 值范围之上，古菌丰度急剧下降近 4 倍，在 pH 值 5.1 至 5.2 时达到最小值。在这个 pH 值范围内，古菌 16S rRNA 基因拷贝数的低丰度随后急剧增加近 150 倍，导致古菌和细菌拷贝数之间的比例从 pH 值 8 时的最小值 0.002 增加到 0.07 以上。古菌对 pH 值的非均匀响应可能反映了群落组成沿梯度的变化，一些古菌适应酸性条件，而另一些古菌适应中性至略碱性条件。这一观点得到了古菌、细菌和真菌在考察 pH 值梯度上下端时相互作用（竞争）结果对比的观察结果的支持。
