Members of the verrucomicrobial clade ‘Candidatus Udaeobacter’ rank among the most dominant bacterial phylotypes in soil. Nevertheless, despite this global prevalence, in-depth analyses with respect to pH preferences of ‘Ca. Udaeobacter’ representatives are still lacking. Here, we utilized a recently designed primer pair, specifically targeting ‘Ca. Udaeobacter’, to investigate links between soil pH and the abundance as well as phylotype composition of this largely unexplored verrucomicrobial clade. Based on 150 forest and 150 grassland soils, comprising a broad pH range, we determined the highest total abundance of ‘Ca. Udaeobacter’ in strongly acidic soil (pH, ~5.1) and, noteworthy, in ultra-acidic soil (pH < 3.5) and at a pH ≥ 7, its abundance drastically declined. When we analysed the six most dominant amplicon sequence variants affiliated with ‘Ca. Udaeobacter’ separately, their abundances peaked within a pH range of approximately 4.7–5.2, and only in one case at slightly acidic soil pH (pH, 6.1). Our study benefits from a combination of quantitative real-time PCR and high-throughput amplicon sequencing, enabling for the first time a highly specific abundance analysis of representatives affiliated with ‘Ca. Udaeobacter’, which revealed that this globally abundant verrucomicrobial clade shows preferences for acidic soil.

中文翻译：

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无处不在的土壤疣状微生物进化枝“Candidatus Udaeobacter”显示出对酸性 pH 值的偏好

疣状微生物进化枝“ Candidatus Udaeobacter”的成员是土壤中最主要的细菌系统发育型之一。然而，尽管这种全球流行，深入分析关于 ' Ca的 pH 偏好。Udaeobacter 的代表仍然缺乏。在这里，我们使用了最近设计的引物对，专门针对 ' Ca。Udaeobacter，以研究土壤 pH 值与这种很大程度上未开发的疣状微生物进化枝的丰度和系统型组成之间的联系。基于 150 个森林和 150 个草地土壤，包括广泛的 pH 值范围，我们确定了最高总丰度的 ' Ca. Udaeobacter' 在强酸性土壤 (pH, ~5.1) 中，值得注意的是，在超酸性土壤 (pH < 3.5) 和 pH ≥ 7 中，其丰度急剧下降。当我们分析与 ' Ca相关的六个最主要的扩增子序列变体时。Udaeobacter 分别在 4.7-5.2 的 pH 值范围内达到峰值，并且仅在微酸性土壤 pH 值（pH 6.1）的情况下达到峰值。我们的研究受益于定量实时 PCR 和高通量扩增子测序的结合，首次实现了对与 ' Ca相关的代表的高度特异性丰度分析。Udaeobacter'，这表明这种全球丰富的疣状微生物进化枝显示出对酸性土壤的偏好。