抄録
MPN (most probable number) method has been used to quantify nitrifiers in activated sludge, and it was very useful for enumerating nitrifying activity. However, it takes about one month to get the results and requires a complicated operation. Consequently, in last decade, several immunological and molecular methods such as ELISA (Enzyme-Linked Immunosorbent Assay) and FISH (Fluorescence in situ hybridization) methods have been developed to quantify nitrifiers rapidly. In this study, to enumerate ammonia oxidizing bacteria (AOB) population in activated sludge more rapidly, a new quantification method, multi-well filtration ELISA using a monoclonal antibody against Nitrosomonas europaea was developed. The threshold of the calibration curve using N. europaea with multi-well filtration ELISA method was about 4.0×105 cells⋅ml-1, which was lower than that of normal ELISA. This means that the quantification range of AOB was extended. Furthermore, by using the multi-well filtration ELISA method, the bestowing time for biomass enumerating was decreased to 5 hours.
According to comparison of multi-well filtration ELISA, MPN and FISH methods, the property of multi-well filtration ELISA was more interrelated with that of MPN than that of FISH method when quantify AOB in activated sludge under practical conditions. Furthermore, multi-well filtration ELISA took results the most quickly among them.
