Open AccessSubstrate‐dependent denitrification of abundant probe‐defined denitrifying bacteria in activated sludge
Author(s) -
MorganSagastume Fernando,
Nielsen Jeppe Lund,
Nielsen Per Halkjær
Publication year - 2008
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/j.1574-6941.2008.00571.x
Subject(s) - denitrifying bacteria , denitrification , nitrite , alphaproteobacteria , biology , nitrate , gammaproteobacteria , betaproteobacteria , activated sludge , environmental chemistry , population , volatile suspended solids , nitrite reductase , microbiology and biotechnology , food science , biochemistry , ecology , chemistry , environmental engineering , organic chemistry , wastewater , 16s ribosomal rna , actinobacteria , sociology , gene , nitrogen , engineering , demography
The denitrification capacity of different phylogenetic bacterial groups was investigated on addition of different substrates in activated sludge from two nutrient‐removal plants. Nitrate/nitrite consumption rates (CRs) were calculated from nitrate and nitrite biosensor, in situ measurements. The nitrate/nitrite CRs depended on the substrate added, and acetate alone or combined with other substrates yielded the highest rates (3–6 mg N gVSS −1 h −1 ). The nitrate CRs were similar to the nitrite CRs for most substrates tested. The structure of the active denitrifying population was investigated using heterotrophic CO 2 microautoradiography (HetCO 2 ‐MAR) and FISH. Probe‐defined denitrifiers appeared as specialized substrate utilizers despite acetate being preferentially used by most of them. Azoarcus and Accumulibacter abundance in the two different sludges was related to differences in their substrate‐specific nitrate/nitrite CRs. Aquaspirillum ‐related bacteria were the most abundant potential denitrifiers ( c . 20% of biovolume); however, Accumulibacter (3–7%) and Azoarcus (2–13%) may have primarily driven denitrification by utilizing pyruvate, ethanol, and acetate. Activated sludge denitrification was potentially conducted by a diverse, versatile population including not only Betaproteobacteria ( Aquaspirillum, Thauera, Accumulibacter , and Azoarcus ) but also some Alphaproteobacteria and Gammaproteobacteria , as indicated by the assimilation of 14 CO 2 by these probe‐defined groups with a complex substrate mixture as an electron donor and nitrite as an electron acceptor in HetCO 2 ‐MAR–FISH tests.