Spatio-Temporal Variations in the Abundance and Community Structure of Nitrospira in a Tropical Bay

Nitrospirais the most diverse genus of nitrite-oxidizing bacteria, and its members are widely spread in various natural and engineered ecosystems. In this study, the phylogenetic diversity ofNitrospiraand monthly changes of its abundance from Zhanjiang Bay were investigated. Phylogenetic analysis showed that among 58 OTUs with high abundance, 74% were not affiliated with any previously describedNitrospiraspecies, revealing a previously unrecognized diversity of coastalNitrospira. The abundances of bothNitrospiraandNitrospinaexhibited a significantly monthly change. During most of the months, abundance ofNitrospinawas greater than that ofNitrospira. In particle-attached communities, either abundance ofNitrospinaorNitrospirawas highly correlated with that of ammonia-oxidizing archaea (AOA), whereas abundance of ammonia-oxidizing bacteria was only highly correlated with that ofNitrospina. In free-living communities, either abundance ofNitrospinaorNitrospirawas correlated only with that of AOA. These results suggest that bothNitrospiraandNitrospinacan be involved in nitrite oxidation by coupling with AOA, butNitrospinamay play a greater role thanNitrospirain this tropical bay.