Effects of ammonium supply deprivation on ammonia oxidation activity and ammonia oxidizing microorganisms in filter materials used in a marine bioreactor
2018
Imai, T. (National Research Institute of Fisheries and Environment of Inland Sea, Japan Fisheries Research and Education Agency, Takamatsu, Kagawa (Japan). Stock Enhancement and Aquaculture Department) | Dehama, K. | Sakami, T. | Takashi, T. | Morita, T. | Imai, S. | Yamamoto, Y. | Oka, M.
Effects of ammonium supply deprivation on ammonia oxidation activity and nitrifying microorganism communities in filter materials were examined to present appropriate management methods for bioreactors after the termination of rearing. Ammonia oxidation activities were measured using ceramic filter materials kept in artificial seawater without any ammonium additions for 24 weeks at 25℃ The nitrifying activities decreased to 97.8% and 78.2% of the initial after 1 and 2 weeks respectively. Subsequently, the activities gradually decreased to 5.4% after 24 weeks of incubation. The relative abundance of archaeal amoA gene in the filter materials kept in ammonia deprivation for 24 weeks was similar to that of the initial one. On the other hand, the relative abundance of bacterial amoA gene reduced to ca. half of the initial one. These results lead to the following management method for biological filters after the termination of rearing: 1) To maintain a high activity level of filter materials, an ammonium supply is necessary in every week. 2) If the bioreactor is maintained without an ammonium supply, prior to the next use an additional ammonium supply as booster is necessary for re-activation of the filter materials.
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