Abstract：
Simultaneous nitrogen and phosphorus removal (SNPR) biofilm system is an effective wastewater treatment process. However, the understanding on the mechanism of functional microorganisms driving SNPR is still limited, especially the role of complete ammonia oxidation (comammox) Nitrospira and glycogen-accumulating organisms (GAO). In this study, a sequencing batch biofilm reactor (SBBR) performing SNPR was operated for 249 d. Based on the 16S rRNA gene, comammox amoA amplicon sequencing, metagenomics and batch experiment, we found that comammox Nitrospira was the main ammonia-oxidizing microorganisms (AOM) and provided nitrite for anaerobic ammonia oxidation (anammox) bacteria (AnAOB). Besides, GAO was dominated by the bacteria of genus Defluviicoccus and played a primary role in reducing nitrate rather than nitrite. Fluorescent in situ hybridization (FISH) analysis confirmed that Nitrospira was enriched in the inner layer of the biofilm. Thus, we put forward a novel insight into the mechanism of SNPR biofilm system. Comammox Nitrospira was responsible for nitrite and nitrate production in the inner biofilm, and AnAOB consumed the produced nitrite during the anammox process. While GAO reduced nitrate to nitrite and polyphosphate-accumulating organisms (PAO) converted nitrite to dinitrogen via denitrifying phosphorus removal in the outer biofilm. These findings provide a new understanding in SNPR biofilm system.
摘要：
同步脱氮除磷（SNPR）生物膜系统是一种有效的废水处理工艺。然而,对功能性微生物驱动SNPR的机制的理解仍然有限，特别是完全氨氧化（Comammox）硝基螺旋体和糖原积累生物（GAO）的作用。在这项研究中,进行SNPR的测序分批生物膜反应器（SBBR）运行249d。基于16SrRNA基因，ComammoxamoA扩增子测序，宏基因组学和批量实验，我们发现ComammoxNitrospira是主要的氨氧化微生物（AOM），并为厌氧氨氧化（anammox）细菌（AnAOB）提供亚硝酸盐。此外,GAO以Defluviicoccus属细菌为主，在还原硝酸盐而不是亚硝酸盐中起主要作用。荧光原位杂交(FISH)分析证实Nitrospira富集在生物膜的内层中。因此，我们对SNPR生物膜系统的作用机制提出了新的见解。ComammoxNitrospira负责在内部生物膜中产生亚硝酸盐和硝酸盐，AnAOB在厌氧氨氧化过程中消耗了产生的亚硝酸盐。当GAO将硝酸盐还原为亚硝酸盐时，聚磷酸盐积累生物（PAO）通过外部生物膜中的反硝化除磷将亚硝酸盐转化为二氮。这些发现为SNPR生物膜系统提供了新的理解。
