Validation of ammonia-oxidizing archaea and comammox Nitrospira for commercial application

硝化作用（即氨通过亚硝酸盐氧化为硝酸盐）是自然和工程系统中重要的微生物过程。废物的降解和水生物种的代谢产生氨，这种含氮化合物对水生生物是有毒的，除非处理。在已建立的水族生物过滤器中，硝化微生物将氨氧化为毒性较小的最终产物硝酸盐。新建立的水族馆通常补充与Hagen Industries产品“循环”相关的氨氧化细菌（AOB），以帮助建立硝化作用，防止毒性和相关的鱼类疾病和死亡。虽然历史上认为好氧硝化作用分为AOB和亚硝酸盐氧化菌（NOB），但最近发现了氨氧化古菌（AOA）和完全氨氧化（comammox）硝化螺旋菌，它们能够通过亚硝酸盐将氨完全氧化为硝酸盐。我们实验室的数据表明，AOA和comammox硝化螺旋菌在水族馆生物过滤器中占主导地位，但在Cycle中却不存在。拟议的NSERC联盟项目将调查淡水水族环境中AOA和comammox硝化螺旋菌的硝化能力，并将为Hagen Industries开发改进的循环产品提供有用的数据。现有的AOA和comammox硝化螺旋菌富集培养物将进一步富集，分离和混合培养物的硝化活性将根据当前循环产物进行评估。将研究一种沸石（“沸石”）底物作为含有AOA和comammox硝化螺旋细胞的微生物生物膜载体的能力，并使用qPCR和显微镜对微生物生长进行量化和可视化。在不同的生长和储存条件下，将评估AOA和comammox Nitrospira在含沸石培养基上的长期活力，以研究储存对活性的潜在时间变化。改进的循环原型产品将在淡水水族箱中使用微生物群落分析和水化学分析进行评估。通过这项拟议的工作所取得的发现将通过与哈根工业公司的合作直接支持加拿大人，并将进一步为加拿大的应用淡水生态学和硝化研究作出贡献。

Nitrification (i.e., ammonia oxidation to nitrate via nitrite) is an important microbial process within natural and engineered systems. Waste degradation and the metabolism of aquatic species produces ammonia, and this nitrogenous compound is toxic to aquatic life unless treated. In an established aquarium biofilter, nitrifying microorganisms oxidize ammonia to the less-toxic end product nitrate. Newly established aquaria are often supplemented with ammonia-oxidizing bacteria (AOB) associated with the product "Cycle" from Hagen Industries to help establish nitrification and prevent toxicity and associated fish disease and death. Although aerobic nitrification was historically thought to be divided between AOB and nitrite-oxidizing bacteria (NOB), ammonia-oxidizing archaea (AOA) and complete ammonia oxidizing (comammox) Nitrospira, capable of fully oxidizing ammonia to nitrate via nitrite, have been recently discovered. Data from our laboratory show that AOA and comammox Nitrospira dominate aquarium biofilters yet are absent from Cycle. This proposed NSERC Alliance project will investigate the nitrifying capabilities of AOA and comammox Nitrospira within the context of freshwater aquaria, and will generate data useful to Hagen Industries for development of an improved Cycle product. Existing AOA and comammox Nitrospira enrichment cultures will be further enriched and the nitrification activity of isolated and mixed cultures will be evaluated against the current Cycle product. A clinoptilolite ("zeolite") substrate will be investigated for its ability to act as a carrier for microbial biofilm containing AOA and comammox Nitrospira cells, with qPCR and microscopy used to quantify and visualize microbial growth. The long-term viability of AOA and comammox Nitrospira on a zeolite-containing medium will be evaluated under different growth and storage conditions to investigate potential temporal changes in activity due to storage. An improved Cycle prototype product will be evaluated within freshwater aquaria using microbial community profiling and water chemistry analyses. The discoveries made through this proposed work will directly support Canadians through collaboration with Hagen Industries and will further contribute to Canadian-based applied freshwater ecology and nitrification research.