利用固定化細胞降解Methyl Orange 染料

Biodegradation of Methyl Orange by Suspended and Immobilized Pseudomonas putida mt2

陳芳草(Phuong-Thao Tran)

指導教授 ： 莊瑞鑫

共同指導教授 ： 藍祺偉(Chi-Wei Lan)

元智大學/工程學院/化學工程與材料科學學系/碩士(2009年)

摘要

利用固定化細胞降解Methyl Orange 染料

關鍵字

生物降解 ； 固定化

並列摘要

Azo dyes which are considered to be the most recalcitrant and persistent among all groups of dye were biodegraded by various kinds of bacteria. In this study, the decolorization of Methyl Orange was determined under different conditions by non-immobilized and immobilized Pseudomonas putida mt2.
For non-immobilized cell system, it was further confirmed that decolorization was much more favorable under anoxic condition since no dye degradation was obtained with 200 rpm shaking, whereas 100% dye was removed in static condition after 3 incubation days. Temperature and pH dependences were evaluated based on the specific decolorization rate and the equilibrium conversion values to investigate the highest capability of Pseudomonas putida mt2 for decolorization in static condition. The optimal temperature range is quite narrow (33oC to 35oC) and the decolorization seems not to be suitable in acidic medium since the optimal pH for methyl orange decolorization occurred at pH 7.0 and significantly decreased at pH 5.0. The Michalis Menten equation was utilized to establish the dependence of the specific decolorization rate on the concentration of dye. The kinetic parameters of Vmax and Km were predicted up to 7.5 mg g-1 h-1 and 283 mg L-1, respectively. External diffusion coefficient kL was evaluated 7.5 x 10-6 cm s-1.
The Ca-alginate immobilized cells can not improve aerobic degradation when the dye color decreased insignificantly but completely disappeared under anaerobic condition. The optimal range of pH and temperature were obtained at 7 to 9 and 35oC to 37oC, respectively. The effects of initial biomass and initial dye concentration were also determined to confirm the predominance of immobilized cells on dye treatment when comparing with free suspended cells. Kinetics parameters were also determined to give the values of Vmax of 6.3 mg g-1 h-1 and Km of 257 mg L-1. The internal diffusion coefficient inside the beads was also investigated to give the value of 6.2 x 10-5 cm2 s-1.
Paint-PVA biofilm was created to immobilize cells instead of Ca-alginate beads when the integrity of beads was not fully maintained. Since the degradation took very long duration, the procedure of biofilm preparation was tried to recover cell’s activity. Better expression was obtained with twice adaptation. Paint-PVA immobilized cells showed the best performance on biodegradation at 35oC to 37oC, the identical optimal temperature rang with Ca-alginate immobilized cells, but the favorable range of pH is quite large from 5 to 9. In this system, the kinetics was also done to obtain the values of Vmax of 2.66 mg g-1 h-1 and Km of 161 mg L-1. The slow biodegradation rate was explained by small value of diffusion coefficient of 2.12 x 10-7 cm s-1.

並列關鍵字

Biodegradation ； Immobilization

參考文獻

Backer L. De and Baron G. Effective diffusion and tortuosity in a porous glass immobilized matrix. Applied Microbiology Biotechnology, (1993) 39, 281-284.

Balanca E. Barragán, Carlos Costa, M. Carmen Márquez, Biodegradation of azo dyes by bacteria inoculated on solid media. Dyes and Pigments 75 (2007) 73-81.

Bai M. D., Chao Y. C., Lin Y. H., Lu W. C., and Lee Hu T., Immobilized biofilm used as seeding source in batch biohydrogen fermentation. Renewable Energy (34) 2009 p 1969-1972.

Brown D., Laboureur P., The degradation of dyestuffs: Part I. Primary biodegradation under anaerobic conditions. Chemosphere 12 (3) 1983 397-404

Chang J. S., Chou C., Lin Y. C., Lin P. J., Ho J. Y. and Lee Hu T., Kinetic characteristics of bacterial azo dye decolorization by Pseudomonas luteola. Wat. Res. Vol35, No. 12, pp 2841-2850, 2001.