title: Nitric oxide preferentially inhibits nitrite oxidizing communities with high affinity for nitrite.
abstract: The prerequisite to the development success of the novel mainstream processes partial nitritation/anammox is the out-selection of nitrite oxidizing bacteria (NOB). A recent study suggested that this could be achieved through NO production by ammonium oxidizing bacteria under cyclic oxic-anoxic conditions. Indeed, it is known that among NOB, Nitrobacter species are reversibly inhibited by NO. However, the effect of NO on the activity of the NOB genus Nitrospira is not studied so far. Such an understanding is needed, since Nitrospira related NOB are mostly prevailing in sewage treatment plants. This study quantified the effect of NO on the nitratation activity of sludge types with different Nitrobacter/Nitrospira ratios. In an oxic bubbling column, a dosage of 4.4 mg NO L(-1) d(-1) (∼2 μg NO-N L(-1) in liquid phase) inhibited the Nitrobacter dominated sludge with 24%. For the Nitrospira dominated sludge types, the inhibition was strongly correlated with the nitrite half saturation constant (K(s)) ranging from 0% to 30-50% and 60-80% inhibition of the nitrite oxidation for K(s) of 0.72, 0.36 and 0.06 mg NO2(-)-N L(-1), respectively. This study showed that nitrifying communities with high affinity for nitrite and low specific nitrite oxidation rates (K-strategists) can be strongly inhibited by NO. The degree of inhibition could be confirmed in a set-up with NO dosage through an artificial alginate-based biofilm, ensuring a more direct contact between NO and the microorganisms.
authors.affiliation: Laboratory of Microbial Ecology and Technology (LabMET), Ghent University, Coupure Links 653, 9000 Gent, Belgium.
authors.forename: Emilie N P
authors.initials: EN
authors.lastname: Courtens
authors.affiliation: Department of Earth and Environmental Engineering, Columbia University, 500 West 120th Street, New York, NY 10027, United States.
authors.forename: Haydée
authors.initials: H
authors.lastname: De Clippeleir
authors.affiliation: Laboratory of Microbial Ecology and Technology (LabMET), Ghent University, Coupure Links 653, 9000 Gent, Belgium. Electronic address: Siegfried.Vlaeminck@UGent.be.
authors.forename: Siegfried E
authors.initials: SE
authors.lastname: Vlaeminck
authors.affiliation: Laboratory of Microbial Ecology and Technology (LabMET), Ghent University, Coupure Links 653, 9000 Gent, Belgium.
authors.forename: Robin
authors.initials: R
authors.lastname: Jordaens
authors.affiliation: Department of Earth and Environmental Engineering, Columbia University, 500 West 120th Street, New York, NY 10027, United States.
authors.forename: Hongkeun
authors.initials: H
authors.lastname: Park
authors.affiliation: Department of Earth and Environmental Engineering, Columbia University, 500 West 120th Street, New York, NY 10027, United States.
authors.forename: Kartik
authors.initials: K
authors.lastname: Chandran
authors.affiliation: Laboratory of Microbial Ecology and Technology (LabMET), Ghent University, Coupure Links 653, 9000 Gent, Belgium.
authors.forename: Nico
authors.initials: N
authors.lastname: Boon
mesh_terms: D019149:Bioreactors / Q000382:microbiology*; D059013:Microbial Consortia / Q000187:drug effects / Q000502:physiology*; D009569:Nitric Oxide / Q000378:metabolism* / Q000494:pharmacology; D009573:Nitrites / Q000378:metabolism*; D009576:Nitrobacter / Q000378:metabolism; D010084:Oxidation-Reduction; D012722:Sewage / Q000382:microbiology*
chemical_list: D009573:Nitrites; D012722:Sewage; D009569:Nitric Oxide
keywords: Activated sludge; Energy-positive; Greenhouse gases; Nitrifier intermediates; Nitrous oxide