FISH法を適用した包括固定化担体内でのアンモニア酸化細菌の動態解析 Quantitative Monitoring of Ammonia Oxidizing Bacteria in PVA-immobilized Pellets by Fluorescent in situ Hybridization (FISH)
Dynamic behavior of Nitrosomonas cells immobilized in PVA gel pellets was investigated by fluorescent in situ hybridization (FISH) of oligonucleotide probes. Two laboratory-scale reactors were seeded with PVA-immmobilized Nitrosomonas cells, and then operated for 160 days by feeding with either a synthetic wastewater containing ammonium solely or a synthetic wastewater composed of ammonium and organic source (acetate). The nitrogen loading on the first reactor (organic-free) was varied from 0.2 up to 0.6kgN·m-3·d-1 by stepwise reducing hydraulic retention time, while the second reactor was operated by varying the C/N ratio of the feed from 0 to 0.8.The first reactor (organic-free) achieved 99% of ammonia removal at 300mg-N·l-1·d-1, and ammonia-oxidation activity per unit pellet volume remained unchanged above 4.5 mg-N·ml-1·d-1 throughout 160 days operation. On the other hand, a severe deterioration in ammmonia oxidation was observed in the second reactor (organic-fed) when the feed C/N ratio was increased to 0.8. For the both reactors, the presence ratio of Nitrososnonas cells to DAPI-stained total cells decreased to below 2% within the initial 90 days operation, regardless of the pressence of organic source in the feed. Nitrosomonas cells were present only up to 50μm-depth of the pellets in the form of large cell clusters. The cluster-forming growth of Nitrosomonas tended to break the lattice-structure of PVA gel material, causing the disappearance of these bacteria from the pellets.
- 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(7), 600-607, 1999-07