Abundance, diversity and physiological preferences of comammox Nitrospira in urban groundwater

摘要

Complete ammonia oxidizer (comammox Nitrospira), catalyze complete nitrification process in a single organism, are frequently detected in groundwater ecosystem. However, the ecological niches and environmental driving factors of comammox Nitrospira in urban groundwater are largely unknown. Here we investigated the commu-nities of ammonia oxidizers in urban groundwater located in Shanghai city, China. Quantitative analysis demonstrated the dominance of comammox Nitrospira over classical ammonia oxidizers (ammonia-oxidizing archaea and bacteria, AOA and AOB). Phylogenetic analysis showed clades B and A2 comprise the majority of comammox Nitrospira groups. Temperature was one of the most vital factors affecting comammox Nitrospira community. Furthermore, clade A comammox Nitrospira can be enriched by urea substrate, which was in line with the ability of utilizing urea by the pure clade A comammox culture Nitrospira inopinata. In addition, we observed that relatively low temperature (<20 C-degrees) and high copper levels (>0.04 mg L-1) can stimulate the growth of comammox Nitrospira. Overall, this study revealed the presence, diversity and physiological prefer-ences of comammox Nitrospira in urban groundwater nitrification, shedding insights on the ecological roles of comammox Nitrospira in subsurface environment.

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