FISH法を適用した生物膜内硝化細菌の菌数計測と空間分布の観察 Direct Cell Counting and Observation of Spacial Distribution of Nitrifies in Aerobic Biofilms by FISH (fluorescent in situ hybridization)
Abundance and spacial distribution of nitrifying bacteria in aerobic biofilm consortia were investigated by using fluorescent in situ hybridization (FISH) with 16SrRNA-targeted oligonucleotide probes. The biofilms were developed in a novel reactor named downflow hanging sponge-cubes (DHS), which was employed as a cost-effective aerobic post-treatment unit after an UASB anaerobic pre-treatment unit receiving municipal sewage. Microscopic direct counting of nitrifying bacteria detected by the FISH technique was carried out to disintegrated biofilm samples, which were obtained by squeezing the sponge-cubes at different reactor height locations. The cell enumeration suggested that the DHS biomass contained 1.4×109-1.2×108 cells·ml-1 cube of Nitrosomonas and 1.8×108-0.15×108 cells·ml-1-cube of Nitrobacter, giving the presence ratio to total cells (detected by DAPI-staining) at 1.4% and 0.18%, respectively. Cell concentrations of both nitrifying bacteria were well correlated with ammonia-oxidizing and nitrite-oxidizing activities evaluated by batch tests. Application of the FISH technique to thinsectioned intact biofilm revealed that both Nitrosomonas and Nitrobacter were rather present in the interior space of sponge-cubes, as attached onto sponge materials. A relatively small amount of Nitrosomonas was observed only until 50μm-depth outer layer of the thick biofilm formed on the surface of sponge-cubes.
- 水環境学会誌 = Journal of Japan Society on Water Environment
水環境学会誌 = Journal of Japan Society on Water Environment 22(2), 152-159, 1999-02-10