Investigation of niche specialization in microbial communities is important in assessing consequences of environmental change for ecosystem processes. Ammonia oxidizing bacteria (AOB) and archaea (AOA) present a convenient model for studying niche specialization. They coexist in most soils and effects of soil characteristics on their relative abundances have been studied extensively. This study integrated published information on the influence of temperature and pH on AOB and AOA into several hypotheses, generating predictions that were tested in soil microcosms. The influence of perturbations in temperature was determined in pH 4.5, 6 and 7.5 soils and perturbations in pH were investigated at 15°C, 25°C and 35°C. AO activities were determined by analysing changes in amoA gene and transcript abundances, stable isotope probing and nitrate production. Experimental data supported major predictions of the effects of temperature and pH, but with several significant discrepancies, some of which may have resulted from experimental limitations. The study also provided evidence for unpredicted activity of AOB in pH 4.5 soil. Other discrepancies highlighted important deficiencies in current knowledge, particularly lack of consideration of niche overlap and the need to consider combinations of factors when assessing the influence of environmental change on microbial communities and their activities.

中文翻译：

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对基于温度和pH的氨氧化古细菌和细菌的生态位专门化进行假设的实验测试。

调查微生物群落中的生态位专长对于评估环境变化对生态系统过程的影响非常重要。氨氧化细菌（AOB）和古细菌（AOA）为研究利基专业化提供了一种方便的模型。它们共存于大多数土壤中，并且已经广泛研究了土壤特性对其相对丰度的影响。这项研究将有关温度和pH对AOB和AOA的影响的公开信息整合到了多个假设中，从而产生了在土壤微观世界中进行测试的预测。在pH 4.5、6和7.5的土壤中确定了温度摄动的影响，并在15°C，25°C和35°C下研究了pH摄动。通过分析amoA的变化确定AO活动基因和转录本丰富，稳定的同位素探测和硝酸盐生成。实验数据支持了温度和pH值影响的主要预测，但存在一些重大差异，其中一些可能是由于实验局限性导致的。该研究还提供了在pH 4.5的土壤中AOB活性无法预测的证据。其他差异突出说明了当前知识的重要缺陷，尤其是在评估环境变化对微生物群落及其活动的影响时，没有考虑生态位重叠以及需要考虑多种因素的组合。