抄録
We have proposed a sewage treatment system by combining an anaerobic UASB and an aerobic biofilter reactor in order to diminish energy requirements and excess sludge production. A 17m3 pilot plant system was operated for over 300 days with continuous feeding of domestic raw sewage. The structure on microbial community of sludge samples taken from the aerobic biofilter reactor was analyzed by using clone libraries of 16S rRNA genes. Clone similar to Thiobacillus and Thiothrix was counted at 10 and 7, respectively, among 188 clones randomly selected from the libraries. Oligonucleotide probe Thio840 for fluorescence in situ hybridization (FISH) was newly designed for the specific target of Thiobacillus group. Approximately 7% of DAPI stained total cells in the biofilter sludgehybridized with the probe Thio840. This value was fairly agreed with frequency of the Thiobacillus clones to the libraries. Real-time PCR using SYBR green I was employed with BONE663cF-Thio840R primer set to determine the copy number of 16S rRNA gene originated from Thiobacillus. High concentration of sulfide at 30 mg-S/L in the influent strongly enhanced abundance of the gene of 105 copies/ng levels in total DNA extracted from the aerobic biofilter sludge. As a result, the real-time PCR assay could be an appropriate tool to monitor Thiobacillus cells in sludge. However, the difference of amplification efficiency between PCR standards and target genes is a subject of discussion.
