The ubiquitous soil verrucomicrobial clade ‘Candidatus Udaeobacter’ shows preferences for acidic pH

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