Nitrite reductase (NirK) of Nitrosomonas europaea confers tolerance to nitrite (NO2-). The nirK gene is clustered with three genes of unknown physiological function: ncgABC. At present, this organization is unique to nitrifying bacteria. Here we report that the ncgABC gene products facilitate NirK-dependent NO2- tolerance by reversing the negative physiological effect that is associated with the activity of NirK in their absence. We hypothesize that the ncg gene products are involved in the detoxification of nitric oxide that is produced by NirK.
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http://dx.doi.org/10.1128/JB.187.19.6849-6851.2005 | DOI Listing |
Environ Res
January 2025
Chemical Process Engineering, P.O. Box 4300, FIN-90014 University of Oulu, Oulu, Finland.
A low-cost and renewable magnetite-pine bark (MPB) sorbent was evaluated in continuous-flow systems for the removal of various pharmaceuticals from municipal wastewater effluent following membrane bioreactor (MBR) treatment. A 33-day small-scale column test (bed volume: 791 cm) was conducted using duplicate columns of biochar (BC, Novocarbo) and activated carbon (AC, ColorSorb) as reference for two columns of BC and MPB in order to compare the efficiency of AC and MPB. After the small-scale column test, the pharmaceutical concentrations were generally below the detection limit.
View Article and Find Full Text PDFMicrob Ecol
November 2024
Institute of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), University of Hohenheim, Garbenstr. 13, 70599, Stuttgart, Germany.
Biological nitrification inhibition (BNI) refers to the plant-mediated process in which nitrification is inhibited through rhizospheric release of diverse metabolites. While it has been assumed that interactive effects of these metabolites shape rhizosphere processes, including BNI, there is scant evidence supporting this claim. Hence, it was a primary objective to assess the interactive effects of selected metabolites, including caffeic acid (CA), vanillic acid (VA), vanillin (VAN), syringic acid (SA), and phenylalanine (PHE), applied as single and combined compounds, against pure cultures of various ammonia-oxidising bacteria (AOB, Nitrosomonas europaea, Nitrosospira multiformis, Nitrosospira tenuis, Nitrosospira briensis) and archaea (AOA, Nitrososphaera viennensis), as well as soil nitrification.
View Article and Find Full Text PDFISME Commun
January 2024
Department of Biological Sciences and Biotechnology, Chungbuk National University, 1 Chungdae-ro, Seowon-Gu, Cheongju 28644, Republic of Korea.
Soil microorganisms often thrive as microcolonies or biofilms within pores of soil aggregates exposed to the soil atmosphere. However, previous studies on the physiology of soil ammonia-oxidizing microorganisms (AOMs), which play a critical role in the nitrogen cycle, were primarily conducted using freely suspended AOM cells (planktonic cells) in liquid media. In this study, we examined the growth of two representative soil ammonia-oxidizing archaea (AOA), EN76 and "" MY2, and a soil ammonia-oxidizing bacterium, ATCC 19718 on polycarbonate membrane filters floated on liquid media to observe their adaptation to air-exposed solid surfaces.
View Article and Find Full Text PDFLett Appl Microbiol
August 2024
Institut für Siedlungswasserwirtschaft und Abfalltechnik, Leibniz Universität Hannover, 30167 Hannover, Germany.
The reaction kinetics of lithotrophic ammonia-oxidizing bacteria (AOB) are strongly dependent on dissolved oxygen (DO) as their metabolism is an aerobic process. In this study, we estimate the kinetic parameters, including the oxygen affinity constant (Km[O2]) and the maximum oxygen consumption rate (Vmax[O2]), of different AOB species, by fitting the data to the Michaelis-Menten equation using nonlinear regression analysis. An example for three different species of Nitrosomonas bacteria (N.
View Article and Find Full Text PDFJ Environ Manage
August 2024
School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou, 215009, China; National & Local Joint Engineering Laboratory for Municipal Sewage Resource Utilization Technology, Suzhou University of Science and Technology, Suzhou, 215009, China. Electronic address:
Acidic nitrification, as a novel process for treating wastewater without sufficient alkalinity, has received increasing attention over the years. In this study, a continuous-flow reactor with aerobic granular sludge was successful operated at low pH (<6.5) performing high-rate acidic nitrification.
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