| Summary: | 碩士 === 逢甲大學 === 環境工程與科學所 === 91 === To understand the bacterial regrowth in drinking water distribution system and thereby control the quality of drinking water, this study utilized fluorescent in situ hybridization (FISH) to quantify the biofilms obtained from the laboratory model system, and to monitor the effect of water quality on the biofilm community.
To determine the formamide concentration of the hybridization solution, the specificities of the Alf lb, Bet 42a, and Gam 42a probes were tested on Sphingomonas sp., Acidovorax sp., and Acinetobacter sp. isolated from the biofilms in the laboratory model system. The results showed that these probes all were specific to the target-organisms when adding 20% formamide to the hybridization solution, and hybridizing at 46oC for 1.5 h. Using FISH to analyze the biofilms, which was developed for 28 days and with 48 h of hydraulic retention time, from a water distribution system, it showed that the biofilms community consisted approximately 22 % of α-, 9 % of β-, and 12 % of γ-Proteobacteria. It was found that the structure of the biofilm community changed with time and the incipient biofilms were mostly in cocci or filamentous shapes, and then rod bacteria became more dominant. The change which the biomass of biofilms decreased from 2.46×107 cells/cm2 to 6.2×106 cells/cm2 indicated that affected by water temperature and dissolved organic carbon (DOC) but the structure of the biofilm community remained unaffected. The chloride inhibited the growth of the biofilms but the relationship of water quality and biomass did not correlate well in this study. To better understand the relationship of water quality and biomass, batch experiments and simulation model of water quality need further investigated.
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