The rapid quantification and detection of nitrifying bacteria by using monoclonal antibody method

Monoclonal antibodies against the two kinds of nitrifying bacteria Nitrosom onas europaea (IFO14298) and Nitrobacter winogradskyi (IFO14297) were raise d and isotypes of these monoclonal antibodies, IgM and IgG(1), were success fully obtained. Cross reactivities of these monoclonal antibodies against v arious kinds of representative heterotrophic bacteria turned out to be rela tively low by competitive ELISA. In contrast, these monoclonal antibodies w ere very specific for nitrifying bacteria used as antigens. By means of san dwich ELISA using different isotype monoclonal antibodies such as IgM and I gG(1), calibration curves were successfully developed for quantification of nitrifying bacteria. It was shown that the obtainable lower limit of quant ification of N. europaea and N. winogradskyi were 7.0 x 10(6) N/ml and were 6.0 x 10(5) N/ml, respectively. Nitrifying bacteria in activated sludge of advanced domestic wastewater treatment johkaso were counted by sandwich EL ISA and MPN methods. The bacterial number estimated by MPN method was lower than that estimated by sandwich ELISA, It was indicated that this monoclon al antibody method could be used asa quick and powerful tool for estimating and controlling the population of nitrifying bacteria in the advanced dome stic wastewater treatment processes.