Molecular detection of anammox bacteria in the sediment of West Lake,Hangzhou

Anaerobic ammonium oxidation(anammox) plays a very important role in the marine nitrogen cycle.But reports on the distribution of anammox bacteria in natural freshwater ecosystems are few.We firstly investigated the distribution and diversity of anammox bacteria in the sediment of West Lake by constructing 16S rRNA gene colony libraries.Phylogenetic analysis of 16S rRNA genes showed that the sequences of Brocadia,Kuenenia and Scalindua could be simultaneously detected in the West Lake sediment,which showed a much higher diversity of anammox bacteria than most reported natural ecosystems.Furthermore,two new anammox bacterial clusters which only showed 92.9%~93.3% and 91.6%~92.7% sequence identity to described anammox bacteria were found in the West Lake sediments.The higher anammox bacterial diversity found in the sediment indicated a large variety of suitable ecological niches are provided for different anammox bacteria in West Lake freshwater ecosystems.As opposed to marine sediments where Scalindua bacteria dominated anammox guilds,Kuenenia organisms appeared to be the most common species in West Lake sediment.