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Design of highly phosphorus-enriched periphytic biofilm and its characteristics
Received:March 25, 2021  
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KeyWord:periphytic biofilm;Tetradesmus obliquus;phosphorus;extracellular polymeric substance(EPS)
Author NameAffiliationE-mail
GAO Mengning State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
Zigui Three Gorges Reservoir Ecosystem, Observation and Research Station of Ministry of Water Resources of the People's Republic of China, Yichang 443605, China
College of Resource and Environment, University of Chinese Academy of Sciences, Beijing 100049, China 
 
XU Ying State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
Zigui Three Gorges Reservoir Ecosystem, Observation and Research Station of Ministry of Water Resources of the People's Republic of China, Yichang 443605, China
College of Resource and Environment, University of Chinese Academy of Sciences, Beijing 100049, China 
 
WU Yonghong State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
Zigui Three Gorges Reservoir Ecosystem, Observation and Research Station of Ministry of Water Resources of the People's Republic of China, Yichang 443605, China 
yhwu@issas.ac.cn 
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Abstract:
      Periphytic biofilm is a micro-ecosystem that widely exists in natural surroundings and has the ability for phosphorus(P) entrapment and recovery. To further improve the efficiency of P entrapment by periphytic biofilms, a new type of artificial periphytic biofilm was designed by co-culturing Tetradesmus obliquus and original periphytic biofilm, and the characteristics and mechanism of P entrapment were also investigated. The results showed that compared with the original periphytic biofilm, the presence of Tetradesmus obliquus significantly increased the ability of P entrapment using artificial periphytic biofilm, and the P accumulation contents increased from (2.26 ±0.14) mg ·g-1 to(6.79 ±0.45) mg ·g-1 on the seventh day of the experiment. The artificial periphytic biofilm also had high compactness of the surface cells and porosity, which was beneficial to increase surface P binding sites and enhance P entrapment using artificial periphytic biofilms. Furthermore, the concentrations of intra-and extracellular P entrapped by the artificial periphytic biofilms were increased, partly due to the increase in the relative abundance of photosynthetic microorganisms and the content of extracellular polymeric substance(EPS). The relative abundance of Chlorophyceae and contents of extracellular protein and polysaccharide in the artificial periphytic biofilms increased by 177.6%, 84.6%, and 23.7%, respectively. Moreover, the expression of eight key metabolites involved in histidine and vitamin B6 metabolic pathways were upregulated in artificial periphytic biofilms. The inclusion of Tetradesmus obliquus optimized the community composition of original periphytic biofilms; in particular, the relative abundance of photosynthetic microorganisms promoted the production of EPS and expression of key metabolites. As a result, the P entrapment capacity of the artificial periphytic biofilm was improved. In conclusion, an artificial periphytic with high efficiency in P enrichment was designed and constructed, which optimized the microbial community structure and function of the periphytic biofilm. This study provides a potential and promising approach for entrapping P from high-P-concentration water and wastewater.