This Article Full Text Full Text (PDF) Supplemental material Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Hallin, S. Articles by Pell, M. Search for Related Content PubMed PubMed Citation Articles by Hallin, S. Articles by Pell, M. Agricola Articles by Hallin, S. Articles by Pell, M.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, August 2006, p. 5445-5452, Vol. 72, No. 8
0099-2240/06/$08.00+0     doi:10.1128/AEM.00809-06
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

Metabolic Profiles and Genetic Diversity of Denitrifying Communities in Activated Sludge after Addition of Methanol or Ethanol

Sara Hallin,^* Ingela Noredal Throbäck, Johan Dicksved, and Mikael Pell

Department of Microbiology, Swedish University of Agricultural Sciences, Box 7025, SE 750 07 Uppsala, Sweden

Received 6 April 2006/ Accepted 1 June 2006

External carbon sources can enhance denitrification rates and thus improve nitrogen removal in wastewater treatment plants. The effects of adding methanol and ethanol on the genetic and metabolic diversity of denitrifying communities in activated sludge were compared using a pilot-scale plant with two parallel lines. A full-scale plant receiving the same municipal wastewater, but without external carbon source addition, was the reference. Metabolic profiles obtained from potential denitrification rates with 10 electron donors showed that the denitrifying communities altered their preferences for certain compounds after supplementation with methanol or ethanol and that methanol had the greater impact. Clone libraries of nirK and nirS genes, encoding the two different nitrite reductases in denitrifiers, revealed that methanol also increased the diversity of denitrifiers of the nirS type, which indicates that denitrifiers favored by methanol were on the rise in the community. This suggests that there might be a niche differentiation between nirS and nirK genotypes during activated sludge processes. The composition of nirS genotypes also varied greatly among all samples, whereas the nirK communities were more stable. The latter was confirmed by denaturing gradient gel electrophoresis of nirK communities on all sampling occasions. Our results support earlier hypotheses that the compositions of denitrifier communities change during predenitrification processes when external carbon sources are added, although no severe effect could be observed from an operational point of view.

---

* Corresponding author. Mailing address: Department of Microbiology, Swedish University of Agricultural Sciences, Box 7025, SE 750 07 Uppsala, Sweden. Phone: 46 18 67 32 09. Fax: 46 18 67 33 92. E-mail: Sara.Hallin{at}mikrob.slu.se.

Supplemental material for this article may be found at http://aem.asm.org/.

---

Applied and Environmental Microbiology, August 2006, p. 5445-5452, Vol. 72, No. 8
0099-2240/06/$08.00+0     doi:10.1128/AEM.00809-06
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

This article has been cited by other articles:

• Pratscher, J., Stichternoth, C., Fichtl, K., Schleifer, K.-H., Braker, G. (2009). Application of Recognition of Individual Genes-Fluorescence In Situ Hybridization (RING-FISH) To Detect Nitrite Reductase Genes (nirK) of Denitrifiers in Pure Cultures and Environmental Samples. Appl. Environ. Microbiol. 75: 802-810 [Abstract] [Full Text]