Heise Julia, Müller Hubert, Probst Alexander J, Meckenstock Rainer U
Environmental Microbiology and Biotechnology, University of Duisburg-Essen, Universitätsstr. 5, 45141, Essen, Germany.
Curr Microbiol. 2021 Mar;78(3):894-903. doi: 10.1007/s00284-021-02358-3. Epub 2021 Feb 5.
Aquaponic systems are sustainable solutions for food production combining fish growth (aquaculture) and production of vegetables (hydroponic) in one recirculating system. In aquaponics, nitrogen-enriched wastewater from fish in the aquaculture serves as fertilizer for the plants in the hydroponics, while the nitrogen-depleted and detoxified water flows back to the aquaculture. To investigate bacterial nitrogen-cycling in such an aquaponic system, measurements of nitrogen species were coupled with time-resolved 16S rRNA gene profiling and the functional capacity of organisms was studied using metagenomics. The aquaponic system was consistently removing ammonia and nitrite below 23 µM and 19 µM, and nitrate to steady-state concentrations of about 0.5 mM. 16S rRNA gene amplicon sequencing of sediments exposed in the pump sump revealed that typical signatures of canonical ammonia-oxidising microorganisms were below detection limit. However, one of the most abundant operational taxonomic units (OTU) was classified as a member of the genus Nitrospira with a relative abundance of 3.8%. For this genus, also genome scaffolds were recovered encoding the only ammonia monooxygenase genes identified in the metagenome. This study indicates that even in highly efficient aquaponic systems, comammox Nitrospira were found to participate in ammonium removal at low steady-state ammonia concentrations.
水培养殖系统是一种可持续的粮食生产解决方案，它将鱼类养殖（水产养殖）和蔬菜种植（水培）整合在一个循环系统中。在水培养殖中，水产养殖中鱼类产生的富含氮的废水作为水培中植物的肥料，而氮含量降低且经过解毒的水则回流到水产养殖中。为了研究这种水培养殖系统中的细菌氮循环，对氮物种的测量与时间分辨16S rRNA基因分析相结合，并使用宏基因组学研究了生物的功能能力。该水培养殖系统持续将氨和亚硝酸盐去除至23 μM和19 μM以下，并将硝酸盐去除至约0.5 mM的稳态浓度。对泵池中暴露的沉积物进行16S rRNA基因扩增子测序，结果显示典型的氨氧化微生物特征低于检测限。然而，最丰富的操作分类单元（OTU）之一被归类为硝化螺菌属的成员，相对丰度为3.8%。对于该属，还回收了编码宏基因组中鉴定出的唯一氨单加氧酶基因的基因组支架。这项研究表明，即使在高效的水培养殖系统中，也发现完整氨氧化菌硝化螺菌在低稳态氨浓度下参与铵的去除。
