アンモニア酸化細菌に対するFISH法の実用性評価

抄録

To assess the feasibility of fluorescence in situ hybridization (FISH) method for ammonia-oxidizing bacteria, three experiments were done as follows; 1) re-optimization of experimental conditions for an oligonucleotide probe Nso190 specific for most of ammonia-oxidizing bacteria, 2) enumeration of ammonia-oxidizing bacteria in lab-scale nitrification reactors, municipal wastewater treatment plants and river water by FISH and other available methods, and 3) to evaluate a correlation between ammonia-oxidizing activity and FISH observation. The results indicated that 1) optimal concentration of formamide for Nso190 probe was 25%, 2) as for the nitrification reactors, where high number of ammonia-oxidizing bacteria seem to exist, FISH, antibody bound latex coagulation and dot blot hybridization methods gave consistent results of ammonia oxidizer enumeration, whereas the MPN method showed 1-2 order lower values than other methods, 3) ammonia-oxidizing bacteria can not be quantitatively detected by FISH method in the municipal wastewater treatment plants (WWTPs) and river water where the ammonia loading is rather low, 4) in some cases, ammonia-oxidizing bacteria can not be detected by FISH whereas ammonia oxidizing activity is observed. Improvement of the FISH methods, such as pretreatment of sample and/or techniques of boosting the fluorescence from the target is needed.