The Responses Of Periphyton And The Removal Of Nitrogen And Phosphorus From Water Under The Action Of Indole Acetic Acid(IAA)

Excessive input of nitrogen and phosphorus into waters is one of the main reasons of causing entrophication and harmful algal blooms,which threatens the health and survival of humans,animals and plants.Exploring effective and practical technologies for nitrogen and phosphorus-polluted water purification has become one of the main field in current environmental and ecological science.As an emerging and environmentally friendly microbial method,periphyton biotechnology has been widely studied to the removal of nitrogen and phosphorus in polluted water.Hollow,there are limited research on how to improve efficiency in the nitrogen and phosphorus wastewater purification.Indole acetic acid?IAA?has been tested to promote of plants and microorganisms,and it has been conducted on the phytoremediation technology to improve the restoration efficiency.Therefore,the relationship between periphyton and IAA and the performance of periphyton on removal of nitrogen and phosphorus under the effect of IAA were studied in this article.The study provides a new method for improve the efficiency of nitrogen and phosphorus removal using periphyton,and lays a certain theoretical foundation.This is of great significance to solve the increasingly serious problem of nitrogen and phosphorus pollution in water.In this study,periphyton was used to study its response to IAA of different concentrations?0¹00 mg/L?.Also,the changes and its mechanism of IAA were studied.As well as its effects on nitrogen?2.0 mg/L?and phosphorus?0.5 mg/L?removal.The physiological and biochemical changes of the periphyton were characterized by chlorophyll fluorometry,protein content and enzyme activity.The carbon metabolism diversity and changes microbial community structure?bacteria and fungi?of periphyton were determined by Biolog technology,MiSeq sequencing analysis and phospholipid fatty acid analysis.The conclusion are as follows:?1?IAA has a certain influence on the growth of periphyton.IAA can affect the chlorophyll fluorescence value of periphyton by changing the physicochemical properties of its growth environment by releasing H^+,such as the pH and dissolved oxygen.For example,low concentration of indole acetic acid can promote the chlorophyll fluorescence value of periphyton to a certain extent,while high concentration of indole acetic acid can reduce the chlorophyll fluorescence value of periphyton.Under the action of IAA,the protein content of periphyton increased,and the ATPase activity decreased.In addition,IAA will also affect the carbon metabolism of periphyton,which will change the type of carbon sources used by periphyton.There are different types of carbon source utilization in periphyton by different concentrations of indole acetic acid.?2?Periphyton can reduce the high concentration of exogenous indole acetic acid?25-100mg/L?,and the removal ratios of the IAA of different concentrations can reach to 80%.Under the stress of IAA,the malondialdehyde content of periphyton was gradually accumulated and had little effect on the activity of SOD.Periphyton can regulate its own species composition to adapt to IAA stress by making the communities that produce and tolerate IAA,such as Proteobacteria,become dominant species.?3?The addition of a certain concentration of IAA can promote the removal of nitrogen and phosphorus in the water by the periphyton.Besides,the efficiency of the"periphyton,IAA,nitrogen and phosphorus"coexistence system is better than that of"IAA treatment of periphyton then treatment of nitrogen and phosphorus."This is mainly because the presence of IAA can improve the absorption and enrichment of nitrogen and phosphorus by changing the microbial community structure of periphyton,making periphyton better adapted to the changed environment.Periphyton can also use IAA as a carbon source for further growth and reproduction to achieve a higher removal efficiency.