Study On The Biodiversity And Coexistence Of Anammox And N-DAMO Bacteria In The Rhizosphere Of Emergent Macrophytes Along Lake Banks

Anaerobic ammonium oxidizing?Anammox?bacteria and N-DAMO bacteria can reduce nitrite through ammoxidation and methane oxidation,respectively.These two bacteria have important ecological significance in nitrogen cycle.Nitrite is a common electron acceptor for the metabolism of anammox bacteria and N-DAMO bacteria,so there is a certain competition between the two bacteria coexisting in the freshwater ecosystem.At present,there is still a lack of research on the distribution characteristics and ecological relationship of anammox bacteria and N-DAMO bacteria in the rhizosphere of emergent macrophytes.In this paper,the rhizosphere of emergent macrophytes along the artificial bank of Lake Donghu and the natural bank of Lake Liangzi were used as research objects.The molecular biology techniques such as cloning,sequencing and quantitative PCR were used to research the ecology of two microorganisms in the rhizosphere.In order to explore the community composition and distribution characteristics of the two microorganisms,and reveal the coexistence of the two colonies and the influence of the emergent macrophytes on the coexistence relationship.The main findings were as follows:?1?The experiment confirmed the existence and distribution of anammox bacteria in the rhizosphere of emergent macrophytes in Lake Donghu and Lake Liangzi.The cluster analysis of anammox bacteria in the rhizosphere of emergent macrophytes in Lake Donghu can be divided into three categories:Candidatus Kuenenia,Candidatus Brocadia and New Cluster.The main anammox genus in the rhizosphere of emergent macrophytes in Lake Liangzi was Candidatus Brocadia and Candidatus Jettenia genus,of which Candidatus Brocadia was dominant.?2?N-DAMO bacteria existed in the rhizosphere of emergent macrophytes in Lake Donghu and Lake Liangzi.The cluster analysis of the N-DAMO bacteria in the rhizosphere of emergent macrophytes in these two lakes can be divided into two major branches:Candidatus Methylomirabilis and New Cluster,of which Candidatus Methylomirabilis genus was the dominant genus.?3?The average abundance of anammox bacteria in the rhizosphere of emergent macrophytes along the artificial bank of Lake Donghu was 3.28×10¹⁰ copies g-1 dry sediment,of which the natural bank of Lake Liangzi was 2.41×10¹⁰ copies g^-11 dry sediment.The abundance of anammox bacteria in the rhizosphere of emergent macrophytes in two lakes was lower than that of the non-rhizosphere sampling points,which indicated that emergent macrophytes inhibited the growth of anammox bacteria.?4?The abundance of N-DAMO bacteria in the rhizosphere of macrophytes in Lake Donghu was significantly lower than that in non-rhizosphere.The growth of macrophytes inhibited the growth of N-DAMO bacteria.The abundance of N-DAMO bacteria in the rhizosphere of macrophytes in Lake Liangzi was not significantly different from that in the rhizosphere.The inhibition of macrophytes on N-DAMO bacteria was not obvious.?5?The abundance of anammox bacteria in Lake Donghu was positively correlated with OM,TN,TP,MC of sediment and pH of interstitial water,while there was a positive correlation between the abundance of this species and NH₄⁺-N of interstitial water and OM in Lake Liangzi.Different lake environments have a different impact on the abundance of anammox bacteria.?6?The abundance of N-DAMO bacteria in Lake Donghu was positively correlated with OM,TN and TP of sediment,while there was a positive correlation between the abundance of the bacteria in Lake Liangzi and OM,TN of sediment and NH₄⁺-N of interstitial water,and the lake environment was also significant affected the abundance distribution of N-DAMO bacteria.?7?The abundance ratio of anammox to N-DAMO in the rhizosphere of emergent macrophytes was lower than that of non-rhizosphere,and the presence of emergent macrophytes alleviated the competition between the two bacteria,especially for N-DAMO bacteria was more beneficial.