Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, Central 6, Higashi 1-1-1, Tsukuba, 305-8566, Japan.
Research Organization for Nano & Life Innovation, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480, Japan.
FEMS Microbiol Lett. 2020 Jan 1;367(1). doi: 10.1093/femsle/fnaa025.
In artificial engineered systems, nitrification is a key reaction that accounts for the removal of biological nitrogen. Recently, a single microbe capable of oxidizing ammonia to nitrate, known as a complete ammonia oxidizer (comammox), has been discovered. Although the abundance and diversity of comammox Nitrospira in engineered systems have been identified through molecular-based approaches, the enrichment and isolation of comammox Nitrospira remains a challenge. Therefore, the aim of this study was to enrich comammox Nitrospira from nitrifying granules, which were used to increase the efficiency of biological nitrogen removal in wastewater treatment plants. We sought to accomplish this through the use of a fixed-bed continuous feeding bioreactor. Fluorescence in situ hybridization, 16S rRNA gene amplicon sequencing and qPCR of functional genes were utilized to monitor the growth of nitrifiers including comammox Nitrospira. Cloning of comammox amoA genes identified amoA phylogeny of enriched comammox Nitrospira. This work is an example demonstrating that continuous supply of low ammonium concentrations alongside biomass carriers is effective in cultivating comammox Nitrospira from engineered systems.
在人工工程系统中，硝化作用是去除生物氮的关键反应。最近，发现了一种能够将氨氧化为硝酸盐的单一微生物，称为完全氨氧化菌（comammox）。虽然已经通过基于分子的方法确定了工程系统中 comammox Nitrospira 的丰度和多样性，但 comammox Nitrospira 的富集和分离仍然是一个挑战。因此，本研究的目的是从硝化颗粒中富集 comammox Nitrospira，这是为了提高污水处理厂生物脱氮的效率。我们试图通过使用固定床连续进料生物反应器来实现这一目标。荧光原位杂交、16S rRNA 基因扩增子测序和功能基因 qPCR 用于监测包括 comammox Nitrospira 在内的硝化菌的生长。对 comammox amoA 基因的克隆确定了富集的 comammox Nitrospira 的 amoA 系统发育。这项工作是一个例子，证明了连续供应低浓度氨和生物载体对于从工程系统中培养 comammox Nitrospira 是有效的。
