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Coliform Bacteria and Nitrogen Fixation in Pulp and Paper Mill Effluent Treatment Systems

Authors :
Frederick Archibald
Brian T. Driscoll
Francis Gauthier
Josh D. Neufeld
Source :
Applied and Environmental Microbiology. 66:5155-5160
Publication Year :
2000
Publisher :
American Society for Microbiology, 2000.

Abstract

The majority of pulp and paper mills now biotreat their combined effluents using activated sludge. On the assumption that their wood-based effluents have negligible fixed N, and that activated-sludge microorganisms will not fix significant N, these mills routinely spend large amounts adding ammonia or urea to their aeration tanks (bioreactors) to permit normal biomass growth. N 2 fixation in seven Eastern Canadian pulp and paper mill effluent treatment systems was analyzed using acetylene reduction assays, quantitative nitrogenase ( nifH ) gene probing, and bacterial isolations. In situ N 2 fixation was undetectable in all seven bioreactors but was present in six associated primary clarifiers. One primary clarifier was studied in greater detail. Approximately 50% of all culturable cells in the clarifier contained nifH , of which >90% were Klebsiella strains. All primary-clarifier coliform bacteria growing on MacConkey agar were identified as klebsiellas, and all those probed contained nifH . In contrast, analysis of 48 random coliform isolates from other mill water system locations showed that only 24 (50%) possessed the nifH gene, and only 13 (27%) showed inducible N 2 -fixing activity. Thus, all the pulp and paper mill primary clarifiers tested appeared to be sites of active N 2 fixation (0.87 to 4.90 mg of N liter −1 day −1 ) and a microbial community strongly biased toward this activity. This may also explain why coliform bacteria, especially klebsiellas, are indigenous in pulp and paper mill water systems.

Details

ISSN :
10985336 and 00992240
Volume :
66
Database :
OpenAIRE
Journal :
Applied and Environmental Microbiology
Accession number :
edsair.doi.dedup.....1643c0316d8d32ef3d808a7efb12b75f
Full Text :
https://doi.org/10.1128/aem.66.12.5155-5160.2000