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29 results on '"Chang, J. S."'

5. HLA-Egene polymorphism associated with susceptibility to kawasaki disease and formation of coronary artery aneurysms

Author

Lin, Y.-J., primary, Wan, L., additional, Wu, J.-Y., additional, Sheu, J. J.-C., additional, Lin, C.-W., additional, Lan, Y.-C., additional, Lai, C.-H., additional, Hung, C.-H., additional, Tsai, Y., additional, Tsai, C.-H., additional, Lin, T.-H., additional, Lin, J.-G., additional, Hsueh, K.-C., additional, Huang, Y.-M., additional, Chang, J.-S., additional, and Tsai, F.-J., additional

Published
2009
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28. Development of microbial mercury detoxification processes using mercury-hyperresistant strain of Pseudomonas aeruginosa PU21.

Author

Chang JS and Law WS

Subjects
Bioreactors, Biotechnology instrumentation, Biotechnology methods, Drug Resistance, Microbial, Inactivation, Metabolic, Kinetics, Pseudomonas aeruginosa classification, Pseudomonas aeruginosa growth & development, Species Specificity, Biodegradation, Environmental, Mercury metabolism, Mercury pharmacokinetics, Pseudomonas aeruginosa metabolism
Abstract

A mercury-hyperresistant strain of Pseudomonas aeruginosa PU21 harboring plasmid Rip64 was utilized to develop bioprocesses able to detoxify and recover soluble mercuric ions in aquatic systems. The kinetics of mercury detoxification was investigated to determine the parameters needed for the design of the bioprocesses. Batch, fed-batch, and continuous bioreactors were utilized to evaluate the efficiency and feasibility of each mode of operation. The results showed that the specific mercury detoxification rate was dependent on cell growth phases, as well as the initial mercury concentrations. Cells at the lag growth phase exhibited the best specific detoxification rate of approximately 1.1 x 10(-6) microg Hg/cell/h, and the rate was optimal at an initial mercury concentration of 8 mg/L. In batch operations with initial mercuric ions ranging from 2 to 10 mg/L, the mercuric ions added were rapidly volatilized from the media in less than 2-3 h. With periodic feeding of 3 or 5 mg Hg/L at fixed time intervals, the fed-batch processes had mercury removal efficiencies of 2.9 and 3.3 mg Hg/h/L, respectively. For continuous operations, the effluent cell concentration (Xe) was essentially invariant at 527 and 523 mg/L with the dilution rates (D) of 0.18 and 0.325 h-1, respectively. The increase in mercury feeding concentrations (Hgf) from 1.0 to 6.15 mg Hg2+/L did not affect the steady-state cell concentration (Xe) but forced the effluent mercury concentration (Hge) to increase. The decrease in the dilution rate, however, resulted in lower Hge values. It was also found that sequential mercury vapor absorption columns recovered over 80% of the Hg degrees released from the bioreactor while the residual mercury vapor was subsequently immobilized by an activated carbon trap in the down stream of the absorption column., (Copyright 1998 John Wiley & Sons, Inc.)

Published
1998

29. Biosorption of mercury by the inactivated cells of pseudomonas aeruginosa PU21 (Rip64).

Author

Chang JS and Hong J

Abstract

Biomass of a mercury-resistant strain Pseudomonas aeruginosa PU21 (Rip64) and hydrogen-form cation exchange resin (AG 50W-X8) were investigated for their ability to adsorb mercury. The maximum adsorption capacity was approximately 180 mg Hg/g dry cell in deionized water and 400 mg Hg/g dry cell in sodium phosphate solution at pH 7.4, higher than the maximum mercury uptake capacity in the cation exchange resin (100 mg Hg/g dry resin in deionized water). The mercury selectivity of the biomass over sodium ions was evaluated when 50 mM and 150 mM of Na(+) were present. Biosorption of mercury was also examined in sodium phosphate solution andphosphate-buffered saline solution (pH 7.0), containing 50mM and 150 mM of Na(+), respectively. It was found that the presence of Na(+) did not severely affect the biosorption of Hg(2+), indicating a high mercury selectivity ofthe biomass over sodium ions. In contrast, the mercury uptake by the ion exchange resin was strongly inhibited by high sodium concentrations. The mercury biosorption was most favorable in sodium phosphate solution (pH 7.4), with a more than twofold increase in the maximum mercury uptake capacity. The pH was found to affect the adsorption of Hg(2+)bythe biomass and the optimal pH value was approximately 7.4. The adsorption of mercury on the biomass and the ion exchange resin appeared to follow theLangmuir or Freundlich adsorption isotherms. (c) 1994 John Wiley & Sons, Inc.

Published
1994
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