Community Structure Of Anammox Bacteria And Its Respones To Environment Factors In Sediments Of Ulansuhai Lake

In recent years,the eutrophication of freshwater lakes has become increasingly serious.With the input of vast amounts of nitrogen and phosphorus,the water quality has been deteriorating and the ecological balance of lakes has been seriously damaged.Therefore,the reduction of nitrogen and phosphorus in water is crucial to control eutrophication.A series of material cycling occurred in the lake.These processes have effectively changed the occurrence state and output pathways of substances,such as nitrogen and phosphorus,and have alleviated the eutrophication level of the lake.As the main participants in the material cycle process,microorganisms play an important role in water quality evaluation,and also make great contribution to improving water quality.In particular,the functional microorganisms participating in the nitrogen cycle play a positive role in removing nitrogen from lakes.Many studies found that anaerobic ammonia oxidation function microorganisms have a noticeable effect on removing nitrogen of natural habitats.Therefore,the Lake Ulansuhai was referred as a case study focusing on the key microbiological processes of anaerobic ammonia oxidation?ANAMMOX?in sediments.The shift of community structure,spatial distribution and richness of anaerobic ammonia oxidizing bacteria were deeply analyzed by cloning library and fluorescent quantitative PCR,and the coupling relationships with environmental factors were also illuminated.The main research results were as follows:?1?ANAMMOX bacteria were widely distributed in the sediment of Lake Ulansuhai,its spatial distribution shows obvious heterogeneity.?2?The community composition of ANAMMOX bacteria mainly included Kuenenia,Brocadia and Jenttenia genus,of which the Kuenenia genus had the largest proportion,up to 31.39%.?3?There is a considerable amount of ANAMMOX bacteria in the sediment,accounting for 0.010?0.104%of the total bacteria.The abundance of ANAMMOX bacteria could reach?4.56±0.10?×10⁶??6.85±0.22?×10⁷ 16S rRNA gene copies?g^-1 dry sediment,showing a trend of decreasing first and then increasing from north to south in the Lake Ulansuhai.?4?Correlation analysis showed that pH,TN,NO₃^--N and TP were important environmental factors that affect the composition of ANAMMOX bacteria community.The abundance of ANAMMOX bacteria had an extremely positive correlation with TOC content?R²=0.967,P<0.01?,and a significant positive correlation with NH₄⁺-N?R²=0.909,P<0.05?.