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ANNUAL CONFERENCE :: Abstract Library
Abstract Library
2003 Conference Abstract
| Type of Submission |
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Submission Type: |
Poster Presentation |
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Subject Category: |
Environmental Microbiology |
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| Session Information |
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Presentation Date: |
May 27, 2003 |
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Abstract ID: |
B15 |
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Session: |
Poster 2 |
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Time: |
15:00 |
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| Presenting Author |
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| Other Authors |
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R. ROY, Department of Biology, University of Victoria, Victoria, British Columbia
D. BEAUMIER, Biotechnology Research Institute, National Research Council of Canada, Montreal, Quebec
N. FORTIN, Biotechnology Research Institute, National Research Council of Canada, Montreal, Quebec
B.T. DRISCOLL, Department of Natural Resource Sciences, McGill University, Ste-Anne-de-Bellevue, Quebec
J.R. LAWRENCE, National Water Research Institute, Environment Canada, Saskatoon, Saskatchewan
C.W. GREER, Biotechnology Research Institute, National Research Council of Canada, Montreal, Quebec
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| Title |
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Temporal variations in the microbial activity and composition of river biofilms grown in the presence of nutrients and hexadecane. |
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| Abstract Text |
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In aquatic ecosystems, biofilm bacteria play key roles in biogeochemical cycling and biodegradative activities, although the impact of environmental variables on aquatic biofilms is poorly understood. This study focused on the impact of nutrients, hexadecane (a petroleum hydrocarbon pollutant) and temporal variations on replicated river biofilms. Biofilms were cultivated on polycarbonate strips in rotating annular reactors using South Saskatchewan River water supplemented with carbon, nitrogen, phosphorus, or combined nutrients (CNP), with or without hexadecane, during the fall of 1999 and during the fall of 2001. The impact of these treatments on bacterial activities (nitrification, denitrification, and hexadecane mineralization) and on the occurrence of genes involved in these activities (amoA, nirS-nirK and alkB, respectively) was determined. The presence of nutrients in combination (CNP) had a dramatic positive effect on hexadecane mineralization and nitrification. Denitrification activity and the detection of alkB and nirK by PCR were also significnatly enhanced by CNP. Phosphorus also stimulated nitrification in the absence of hexadecane, and enhanced alkB detection, whether, or not, hexadecane was present. Phosphorus stimulation was less than that observed for CNP. Pre-exposure of biofilms to hexadecane did not stimulate mineralization. Hexadecane had a negative impact on the assessed bacterial activities, although its mineralization by biofilms grown in fall 1999 was about 1.5 times higher than fall 2001 biofilms. Denitrification was initiated faster by fall 1999 biofilms than by fall 2001 biofilms, but reached similar levels after ca. 1 month. Accordingly, nirK was more readily detected in fall 1999 biofilms than with fall 2001 biofilms. These results showed that nutrients (especially P) were limiting for bacterial activity in the South Saskatchewan River water, that hexadecane had a negative impact on bacterial activity, and that biofilms grown in fall 1999 were more active than the ones grown in fall 2001. This study demonstrated that there are interactive effects between nutrients and contaminants, and that the community response to environmental stress can have significant temporal variations. |
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