五氯酚分解菌之分離與及其生理特性研究

• Main Authors: Yang Chu Fang, 楊茱芳
• Other Authors: 李季眉
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/16188320027420971646

碩士 === 國立中興大學 === 環境工程學系 === 91 === The chlorophenolic compounds are common environmental contaminants. Because of the resistance of microbial degradation and the broad toxicity, the chlorophenolic compounds cause serious environmental problems. Several physical, chemical and biological methods had been proposed treating or recovering the chlorophenolic compounds. The biological treatment is superior to the physicochemical methods, because it is more economical and generates lower byproducts than other treatments. In this study, the biological method had been used to isolate and identify the PCP degrading bacteria, which utilize PCP as the substrate, from the PCP contaminated soils. Moreover, the characteristics of PCP degrading bacteria had been investigated. In this research, one strain had been isolated from the PCP contaminated soils and it had been identified as Sphingomonas chlorophenolica by the method based on 16S rDNA gene sequence. The optimum growth temperatures of Sphingomonas chlorophenolica were 28C and 30C by utilizing the glucose and sodium acetate as the substrates, respectively. When the pH values were 6.9 and 7.6, the PCP removal rate had the maximum value and PCP with concentration 75 mg/l could be completely removed in 37 hours. Sphingomonas chlorophenolica had been used to degrade various chlorophenols in this study. The Sphingomonas chlorophenolica cells were capable of degrading 2,3,6-trichlorophenol (2,3,6-TCP), 2,4,6-trichlorophenol (2,4,6-TCP) and 2,3,4,6- tetrachlorophenol (2,3,4,6-TeCP). If the initial concentration of 2,3,6-TCP was lower than 240 mg/l, Sphingomonas chlorophenolica could remove 2,3,6-TCP completely within 31.7 hours. However, the removal efficiency became 98.7% in 140.8 hours, when the initial 2,3,6-TCP concentration was 380 mg/l. As the initial 2,3,6-TCP concentration was increased above 560 mg/l, Sphingomonas chlorophenolica could not degrade 2,3,6-TCP. Sphingomonas chlorophenolica could remove 2,4,6-TCP completely within 30.9 hours when the initial concentration of 2,4,6-TCP was lower than 560 mg/l. The removal efficiency was 84.3% in 99.5 hours with increasing the initial 2,4,6-TCP concentration to 720 mg/l. If the initial concentration of 2,3,4,6-TeCP was lower than 380 mg/l, Sphingomonas chlorophenolica could degrade 2,3,4,6-TeCP completely within 51.4 hours. However, as 2,3,4,6-TeCP concentration was increased to 560 and 720 mg/l, the efficiency of removal 2,3,4,6-TeCP was 65.9% and 43.7% within 110.7 hours, respectively. When the initial concentration of PCP was lower than 380 mg/l, Sphingomonas chlorophenolica could degrade PCP completely within 45.6 hours. With increased PCP concentration to 560 and 720 mg/l, each efficiency of removal PCP decreased to 58.9 % and 34.7% within 165 hours. Cell suspensions of Sphingomonas chlorophenolica were able to completely degrade 2,3,6-TCP, 2,4,6-TCP, 2,3,4,6-TeCP and PCP within 38.1, 15.1, 11.8 and 11.8 hours, and to release concentration 50.1, 60.9, 63.7 and 58.5 mg/l chloride for the same period. The results of calculation indicated that four kinds of chlorophenols were dechlorinated approximately 100% by suspensions of Sphingomonas chlorophenolica. In the presence of supplementary carbon sources (concentration 300 mg/l glucose, pyruvate, sodium acetate and concentration 150 mg/l 2,4,6-TCP, PCP) the removal efficiency of 75 mg/l 2,4-dichlorophenol (2,4-DCP) was not increased. However, PCP or 2,4,6-TCP removal efficiency was increased in the presence of glucose or pyruvate. Four kinds of chlorophenols (2,3,6-TCP, 2,4,6-TCP, 2,3,4,6-TeCP and PCP) were added simultaneously or non-simultaneously as the carbon sources, the experimental results indicated only 2,3,6-TCP in combination with 2,4,6-TCP or 2,3,4,6-TeCP or PCP facilitated 2,3,6-TCP degradation. In this study, Sphingomonas chlorophenolica had been isolated from the PCP contaminated soils successfully and the abilities of Sphingomonas chlorophenolica to degrade PCP were better than the other strains that were reported in past papers. Furthermore, as the results showed, Sphingomonas chlorophenolica was capable of degrading 2,3,6-TCP, 2,4,6-TCP and 2,3,4,6-TeCP. Due to some areas in Taiwan were polluted by PCP even other chlorophenols. Therefore, the Lab-scale studies will be the main works in the further research. Sphingomonas chlorophenolica will be used to degrade the chlorophenolic compounds in those polluted areas and its abilities to degrade the chlorophenolic compounds will be rechecked.