2021 Volume 69 Issue 1 Pages 93-100
The propose of this study was to assess the suitable conditions to preserve filter materials which were attached nitrifying microorganisms for a long period. We investigated the effect of the preservation temperature on the ammonia oxidation activity of filter materials kept in saturated humidity in plastic bags. After the ammonia oxidation activity of filter materials was measured at 25°C, filter materials were removed from seawater and kept at eight temperatures (1-35°C) in plastic bags for 180 days. Ammonia oxidation activity of the filter material preserved at 1°C was similar to that of the initial activity value. In addition, the relative abundance of ammonia-oxidizing archaea and bacteria in the filter materials preserved at 1°C exhibited only a slight decrease of 14% and 10% of the initial abundances, respectively. Activity of filter materials preserved at 5-20°C decreased to about 50%. Greater decrease of activity was recognized in filter materials preserved at over 25°C. An additional preservation experiment over a three year period at 1°C showed that the activity of filter materials remained at 33%. Therefore, highest retention of the ammonia oxidizing microorganism for long preservation of filter materials with nitrification was 1°C in the designed temperature.
