1 Department of Bioscience - Center for Geomicrobiology, Department of Bioscience, Science and Technology, Aarhus University2 Department of Biomedicine - Department of Human Genetics, Department of Biomedicine, Health, Aarhus University3 Department of Biotechnology, Chemistry and Environmental Engineering Aalborg University4 Department of Biomedicine - Forskning og uddannelse, Øst, Department of Biomedicine, Health, Aarhus University5 Department of Clinical Medicine - Molekylær Medicinsk afdeling (MOMA), Department of Clinical Medicine, Health, Aarhus University6 Biotechnology Department, Aalborg University7 Sektion for Bioteknologi8 Aalborg University9 Department of Biomedicine - Forskning og uddannelse, Øst, Department of Biomedicine, Health, Aarhus University10 Department of Clinical Medicine - Molekylær Medicinsk afdeling (MOMA), Department of Clinical Medicine, Health, Aarhus University
Denitrification is essential to the removal of nitrogen from wastewater during treatment, yet an understanding of the diversity of the active denitrifying bacteria responsible in full-scale wastewater treatment plants (WWTPs) is lacking. In this study, stable-isotope probing (SIP) was applied in combination with microautoradiography (MAR)-fluorescence in situ hybridization (FISH) to identify previously unrecognized active denitrifying phylotypes in a full-scale WWTP with biological N and P removal. Acknowledging that different denitrifiers will have specific carbon source preferences, a fully 13C-labelled complex substrate was used for SIP incubations, under nitrite-reducing conditions, in order to maximize the capture of the potentially metabolically diverse denitrifiers likely present. Members of the Rhodoferax, Dechloromonas, Sulfuritalea, Haliangium and Thermomonas were represented in the 16S rRNA gene clone libraries from DNA enriched in 13C, with FISH probes optimized here for their in situ characterization. FISH and MAR confirmed that they were all active denitrifiers in the community. The combined approach of SIP and MAR-FISH represents an excellent approach for identifying and characterizing an un-described diversity of active denitrifiers in full-scale systems.
Environmental Microbiology, 2015, Vol 18, Issue 1, p. 50-64