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

点击翻译按钮获取中文摘要

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.