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Applied and Environmental Microbiology, October 2005, p. 5888-5892, Vol. 71, No. 10
0099-2240/05/$08.00+0     doi:10.1128/AEM.71.10.5888-5892.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.

Improvement of NaNO2-Oxidizing Activity in Nitrobacter vulgaris by Coentrapment in Polyacrylamide Containing Polydimethylsiloxane Copolymer and DEAE-Sephadex

Songping Zhang,1,3 Olof Norrlöw,2 and Estera Szwajcer Dey1*

Pure and Applied Biochemistry, Lund University, Box 124, 221 00 Lund, Sweden,1 Recycling Competence Centre, Kemira Kemi AB, Box 902, 251 09 Helsinborg, Sweden,2 National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, P.O. Box 353, Beijing 100080, People's Republic of China3

Received 26 February 2005/ Accepted 29 April 2005

Removal of nitrite and nitrate from drinking water has attracted great attention in recent years because of the human health risk induced by the exposure to contaminated groundwater and surface water. We have therefore tested a model nitrite oxidation system by coentrapping the NaNO2 oxidizer Nitrobacter vulgaris with polydimethylsiloxane (PDMS) copolymer and DEAE-Sephadex in a polyacrylamide gel. The copolymer and the anion exchanger facilitate the diffusion of oxygen and NaNO2, respectively, into the gel matrix. To test the nitrite-oxidizing activity, the entrapped cells were coupled to a thermal sensor. Coentrapment of 5% (wt/vol) DEAE-Sephadex with Nitrobacter vulgaris increased the nitrite-oxidizing activity by a factor of 3.7 compared to entrapped cells alone, and by the addition of 0.86% (wt/vol) artificial oxygen carrier PDMS copolymer increased the activity further to 4.3 times higher. Operational and storage stability of the coentrapped N.vulgaris also improved. This suggests that this enhanced immobilized cell system can also be used for nitrite oxidation to nitrate in drinking water as an on-line thermally monitored bioreactor.

* Corresponding author. Mailing address: Pure and Applied Biochemistry, Lund University, Box 124, 221 00 Lund, Sweden. Phone: 46 46 2228258. Fax: 46 46 2224611. E-mail: estera.dey{at}tbiokem.lth.se.

Applied and Environmental Microbiology, October 2005, p. 5888-5892, Vol. 71, No. 10
0099-2240/05/$08.00+0     doi:10.1128/AEM.71.10.5888-5892.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.





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