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PROVIDER: PRJNA475741 | ENA |
REPOSITORIES: ENA
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Project description:Anaerobic ammonium-oxidising (anammox) bacteria, members of the ‘Candidatus Brocadiaceae’ family, play an important role in the nitrogen cycle and are estimated to be responsible for about half of the oceanic nitrogen loss to the atmosphere. Anammox bacteria combine ammonium with nitrite and produce dinitrogen gas via the intermediates nitric oxide and hydrazine (anammox reaction) while nitrate is formed as a by-product. These reactions take place in a specialized, membrane-bound compartment called the anammoxosome. Therefore, the substrates ammonium, nitrite and product nitrate have to cross the outer-, cytoplasmic- and anammoxosome membranes to enter or exit the anammoxosome. The genomes of all anammox species harbour multiple copies of ammonium-, nitrite- and nitrate transporter genes. Here we investigated how the distinct genes for ammonium-, nitrite- and nitrate- transport were expressed during substrate limitation in membrane bioreactors. Transcriptome analysis of Kuenenia stuttgartiensis planktonic cells under ammonium-limitation showed that three of the seven ammonium transporter genes and one of the six nitrite transporter genes were significantly upregulated, while another ammonium and nitrite transporter gene were downregulated in nitrite limited growth conditions. The two nitrate transporters were expressed to similar levels in both conditions. In addition, genes encoding enzymes involved in the anammox reaction were differentially expressed, with those using nitrite as a substrate being upregulated under nitrite limited growth and those using ammonium as a substrate being upregulated during ammonium limitation. Taken together, these results give a first insight in the potential role of the multiple nutrient transporters in regulating transport of substrates and products in and out of the compartmentalized anammox cell.
2020-06-05 | GSE148825 | GEO
Project description:Competition among nitrate reducing bacteria (NRB) and sulfate reducing bacteria (SRB) for resources in anoxic environments is generally thought to be governed largely by thermodynamics. It is now recognized that intermediates of nitrogen and sulfur cycling (e.g., hydrogen sulfide, nitrite, etc.) can also directly impact NRB and SRB activities in freshwater, wastewater and sediment, and therefore may play important roles in competitive interactions. Here, using Intrasporangium calvum C5 as a model NRB, we performed comparative transcriptomic and metabolomic analyses to demonstrate that the reduced sulfur compounds cysteine and sulfide differentially inhibit respiratory growth on nitrate, and that inhibition by each can be selectively relieved by a specific carbon source. These findings provide mechanistic insights into the interplay and stratification of NRBs and SRBs in diverse environments.
2020-10-01 | GSE158822 | GEO
Project description:Geobacter sulfurreducens is a widely explored microorganism recognized by its metabolic versatility able to reduce a number of external electron acceptors. In the present study the capacity of this strain to reduce nitrate was evaluated along with its transcriptomic profile under nitrate-reducing conditions and the catalytic role of Pd nanoparticles on the reductive pathway. Results demonstrated that G. sulfurreducens was able to reduce nitrate and important kinetic differences related to the time response were found among the electron donors used (acetate and hydrogen). When using acetate, a delay response on nitrate reduction of 4 days and reduction of 94% of nitrate was achieved, while nitrite was not detected, and all the nitrogen was recovered as ammonium (79.6 ± 5.7 %). The use of hydrogen as electron donor increased 2-fold the maximum rate of nitrate reduction, leading to 93% reduction of nitrate during the first 20 h with recovery of 45% as ammonium, while nitrite was not detected. In addition, transcriptome profiling analysis of G. sulfurreducens under nitrate-reducing conditions using hydrogen or acetate as an electron donor at 2 and 6 days reveals that a core of 146 genes (69 upregulated and 77 downregulated) are differentially expressed in all conditions. Genes related to nitrogen metabolism, such as nrfA and nrfH, gdhA, and amtB, were upregulated in the incubations and RT-qPCR data confirmed upregulations of these genes. Experiments performed with biologically synthesized Pd (Bio-Pd) + G. sulfurreducens cells demonstrated synergistic input of Bio-Pd and the metabolic capacity of G. sulfurreducens. These results expand the metabolic versatility of G. sulfurreducens, which may have important implications in nitrogen cycling in natural environments and engineered systems.
2023-06-01 | GSE179298 | GEO
Project description:Nitrogen metabolism in Aspergillus nidulans is subject to regulation by the GATA transcription factor AreA which is required for the utilization of a wide range of nitrogen sources other than glutamine or ammonium. The level of AreA activity is regulated by intracellular glutamine levels that vary in response to nitrogen supplementation. For nitrate assimilation, which involves two transporters (CrnA, CrnB), nitrate reductase (NiaD) and nitrite reductase (NiiA), the respective genes are subject to regulation at the level of transcription, including nitrogen metabolite repression mediated by AreA and induction mediated by nitrite or nitrate, mediated by a second transcription factor, NirA. Both transcription factors act synergistically to regulate the expression of all four structural genes when nitrogen is limiting or either nitrate or nitrite is available. In this study we dissect the nitrogen limitation effect mediated by AreA form the nitrate/nitrite specific effect mediated by NirA on the transcriptome level. Keywords: Nitrate/nitrogen limitation response
2009-01-01 | GSE10475 | GEO
Project description:Nitrite-oxidizing bacteria are vital players in the global nitrogen cycle that convert nitrite to nitrate during the 2nd step of nitrification. Within this functional guild, the genus Nitrospira is among the most widespread and phylogenetically and physiologically diverse nitrite oxidizers and its members drive nitrite oxidation in many natural and biotechnological ecosystems. Despite their ecological and biotechnological importance, our understanding of Nitrospira’s energy metabolism is still limited. The main bottleneck for a detailed biochemical characterization of Nitrospira is biomass production, since they are slow-growing organisms and fastidious to culture. In this study, we cultured Nitrospira moscoviensis in a continuous stirred tank reactor system (CSTR) allowing constant biomass harvesting. Additionally, this cultivation setup enabled accurate control of physicochemical parameters and thus avoided fluctuating levels of nitrite and accumulation of nitrate. We performed transcriptome analysis and confirmed constant gene expression profiles in the chemostat culture over a period of two weeks. The transcriptomic data supports the predicted core metabolism of N. moscoviensis, including the reductive TCA cycle as a CO2 fixation pathway, the novel bd-like oxidase as terminal oxidase and the octaheme nitrite reductase involved in nitrogen assimilation. Additionally, the expression of multiple copies of respiratory complexes suggests functional differentiation of these copies within the respiratory chain. Transcriptome analysis also suggests a soluble and a membrane-bound gamma subunit as part of the nitrite oxidoreductase (NXR), the enzyme catalyzing nitrite oxidation. Overall, the transcriptome data provided novel insights into the metabolism of Nitrospira supporting the genome-based prediction of key pathways. Moreover, the application of a CSTR to cultivate Nitrospira is an important foundation for future proteomic and biochemical characterizations, which are crucial for a better understanding of canonical and complete nitrifying microorganisms.
2019-07-03 | GSE123406 | GEO
Project description:Chemoautotrophic bacteria from the SUP05 clade often dominate anoxic waters in marine oxygen minimum zones (OMZs) where reduced sulfur can fuel carbon fixation and denitrification. Some members of the SUP05 clade are facultative aerobes that thrive at the boundaries of OMZs where they experience fluctuations in dissolved oxygen (DO). The degree to which SUP05 contribute to nitrate reduction in these regions depends on their sensitivity to oxygen. We evaluated growth and quantified differences in gene expression in Ca. T. autotrophicus strain EF1 from the SUP05 clade under high DO (22 μM), anoxic, and low DO (3.8 μM) concentrations. We show that strain EF1 cells respire oxygen and nitrate and that cells have higher growth rates, express more genes, and fix more carbon when oxygen becomes available for aerobic respiration. Evidence that facultatively aerobic SUP05 are more active and respire nitrate when oxygen becomes available at low concentrations suggests that they are an important source of nitrite across marine OMZ boundary layers.
2020-06-01 | GSE144480 | GEO
Project description:Metal-reducing bacterium that reduces nitrate and nitrite to ammonia
| PRJNA13392 | ENA
Project description:Staphylococcus xylosus is one of the major starter cultures used for meat fermentation because of its crucial role in the reduction of nitrate to nitrite, which contributes to color and flavor development. Despite the long use of these additives, their impact on the physiology of S. xylosus has not yet been explored. We present the first in situ global gene expression profile of S. xylosus in meat supplemented with nitrate and nitrite. More than 600 genes of S. xylosus were differentially expressed at 24 or 72 hours of incubation. They represent more than 20% of the total genes and led us to suppose that addition of nitrate and nitrite to meat leads to a global change in gene expression. This profile revealed that S. xylosus is subject to nitrosative stress caused by reactive nitrogen species generated from nitrate and nitrite. To overcome this stress, S. xylosus has developed several oxidative stress resistance mechanisms, such as modulation of the expression of several genes involved in iron homeostasis and in antioxidant defense. Most of these genes belong to the Fur and PerR regulons respectively. S. xylosus has also counteracted this stress by developing DNA and protein repair. Furthermore, it has adapted its metabolic response—carbon and nitrogen metabolism, energy production and cell wall biogenesis—to the alterations produced by nitrosative stress.
2014-10-08 | GSE61514 | GEO
Project description:Staphylococcus xylosus is one of the major starter cultures used for meat fermentation because of its crucial role in the reduction of nitrate to nitrite, which contributes to color and flavor development. Despite the long use of these additives, their impact on the physiology of S. xylosus has not yet been explored. We present the first in situ global gene expression profile of S. xylosus in meat supplemented with nitrate and nitrite. More than 600 genes of S. xylosus were differentially expressed at 24 or 72 hours of incubation. They represent more than 20% of the total genes and led us to suppose that addition of nitrate and nitrite to meat leads to a global change in gene expression. This profile revealed that S. xylosus is subject to nitrosative stress caused by reactive nitrogen species generated from nitrate and nitrite. To overcome this stress, S. xylosus has developed several oxidative stress resistance mechanisms, such as modulation of the expression of several genes involved in iron homeostasis and in antioxidant defense. Most of these genes belong to the Fur and PerR regulons respectively. S. xylosus has also counteracted this stress by developing DNA and protein repair. Furthermore, it has adapted its metabolic responseM-bM-^@M-^Tcarbon and nitrogen metabolism, energy production and cell wall biogenesisM-bM-^@M-^Tto the alterations produced by nitrosative stress. Microarray was used to evaluate modification in the transcriptome of S. xylosus C2a strain in the presence (N) or absence (V) of nitroso compounds. Three biological replicates collected on separate days for each meat matrix and labelled following a dye-switch design; for each condition one labeling in Cy3 and one in Cy5.
2014-10-08 | E-GEOD-61514 | biostudies-arrayexpress
Project description:We sequenced mRNA from Mtb that had been treated with 5 mM nitrate or was untreated in standard 7H9/ADNaCl medium. This generated the first analysis of gene expression following mycobacterial nitrate respiration. Examination of mRNA levels in Mtb following nitrate respiration, which results in the production of nitrite.
2013-10-21 | E-GEOD-51037 | biostudies-arrayexpress