Trichlorobacter ammonificans, a dedicated acetate-dependent ammonifier with a novel module for dissimilatory nitrate reduction to ammonia.

Autor: Sorokin DY; Department of Biotechnology, Delft University of Technology, Delft, The Netherlands. d.sorokin@tudelft.nl.; Winogradsky Institute of Microbiology, Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, Russia. d.sorokin@tudelft.nl., Tikhonova TV; Bach Institute of Biochemistry, Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, Russia., Koch H; Department of Microbiology, Radboud Institute for Biological and Environmental Sciences, Radboud University, Nijmegen, The Netherlands., van den Berg EM; Department of Biotechnology, Delft University of Technology, Delft, The Netherlands., Hinderks RS; Department of Biotechnology, Delft University of Technology, Delft, The Netherlands., Pabst M; Department of Biotechnology, Delft University of Technology, Delft, The Netherlands., Dergousova NI; Bach Institute of Biochemistry, Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, Russia., Soloveva AY; Bach Institute of Biochemistry, Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, Russia., Kuenen GJ; Department of Biotechnology, Delft University of Technology, Delft, The Netherlands., Popov VO; Bach Institute of Biochemistry, Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, Russia., van Loosdrecht MCM; Department of Biotechnology, Delft University of Technology, Delft, The Netherlands., Lücker S; Department of Microbiology, Radboud Institute for Biological and Environmental Sciences, Radboud University, Nijmegen, The Netherlands. s.luecker@science.ru.nl.
Jazyk: angličtina
Zdroj: The ISME journal [ISME J] 2023 Oct; Vol. 17 (10), pp. 1639-1648. Date of Electronic Publication: 2023 Jul 13.
DOI: 10.1038/s41396-023-01473-2
Abstrakt: Dissimilatory nitrate reduction to ammonia (DNRA) is a common biochemical process in the nitrogen cycle in natural and man-made habitats, but its significance in wastewater treatment plants is not well understood. Several ammonifying Trichlorobacter strains (former Geobacter) were previously enriched from activated sludge in nitrate-limited chemostats with acetate as electron (e) donor, demonstrating their presence in these systems. Here, we isolated and characterized the new species Trichlorobacter ammonificans strain G1 using a combination of low redox potential and copper-depleted conditions. This allowed purification of this DNRA organism from competing denitrifiers. T. ammonificans is an extremely specialized ammonifier, actively growing only with acetate as e-donor and carbon source and nitrate as e-acceptor, but H 2 can be used as an additional e-donor. The genome of G1 does not encode the classical ammonifying modules NrfAH/NrfABCD. Instead, we identified a locus encoding a periplasmic nitrate reductase immediately followed by an octaheme cytochrome c that is conserved in many Geobacteraceae species. We purified this octaheme cytochrome c protein (TaNiR), which is a highly active dissimilatory ammonifying nitrite reductase loosely associated with the cytoplasmic membrane. It presumably interacts with two ferredoxin subunits (NapGH) that donate electrons from the menaquinol pool to the periplasmic nitrate reductase (NapAB) and TaNiR. Thus, the Nap-TaNiR complex represents a novel type of highly functional DNRA module. Our results indicate that DNRA catalyzed by octaheme nitrite reductases is a metabolic feature of many Geobacteraceae, representing important community members in various anaerobic systems, such as rice paddy soil and wastewater treatment facilities.
(© 2023. The Author(s), under exclusive licence to International Society for Microbial Ecology.)
Databáze: MEDLINE
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