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Applied and Environmental Microbiology, March 2001, p. 1375-1379, Vol. 67, No. 3
Center for Biofilm
Engineering1 and Department of Land
Resources and Environmental Sciences,3 Montana
State University, Bozeman, Montana 59717, and Department of
Molecular Genetics, Biochemistry, and Microbiology, University of
Cincinnati College of Medicine, Cincinnati, Ohio
45267-05242
Received 29 August 2000/Accepted 14 December 2000
Previous work with Pseudomonas aeruginosa showed
that catalase activity in biofilms was significantly reduced
relative to that in planktonic cells. To better understand biofilm
physiology, we examined possible explanations for the differential
expression of catalase in cells cultured in these two different
conditions. For maximal catalase activity, biofilm cells required
significantly more iron (25 µM as FeCl3) in the medium,
whereas planktonic cultures required no addition of iron. However,
iron-stimulated catalase activity in biofilms was still only about
one-third that in planktonic cells. Oxygen effects on catalase activity
were also investigated. Nitrate-respiring planktonic cultures produced
approximately twice as much catalase activity as aerobic cultures grown
in the presence of nitrate; the nitrate stimulation effect could also
be demonstrated in biofilms. Cultures fermenting arginine had reduced
catalase levels; however, catalase repression was also observed in
aerobic cultures grown in the presence of arginine. It was concluded
that iron availability, but not oxygen availability, is a major factor affecting catalase expression in biofilms.
0099-2240/01/$04.00+0 DOI: 10.1128/AEM.67.3.1375-1379.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Factors Affecting Catalase Expression in Pseudomonas
aeruginosa Biofilms and Planktonic Cells
*
Corresponding author. Mailing address: Department of
Land Resources and Environmental Sciences, Montana State University, Bozeman, MT 59717. Phone: (406) 994-2190. Fax: (406) 994-3933. E-mail:
timmcder{at}montana.edu.
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