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ELife Aug 2020In order to enter a cell, an ammonium ion must first dissociate to form an ammonia molecule and a hydrogen ion (a proton), which then pass through the cell membrane...
In order to enter a cell, an ammonium ion must first dissociate to form an ammonia molecule and a hydrogen ion (a proton), which then pass through the cell membrane separately and recombine inside.
Topics: Ammonia; Ammonium Compounds; Ion Transport; Nitrosomonas; Oxidation-Reduction
PubMed: 32840481
DOI: 10.7554/eLife.61148 -
The ISME Journal Sep 2023Ammonia oxidising archaea are among the most abundant living organisms on Earth and key microbial players in the global nitrogen cycle. They carry out oxidation of... (Review)
Review
Ammonia oxidising archaea are among the most abundant living organisms on Earth and key microbial players in the global nitrogen cycle. They carry out oxidation of ammonia to nitrite, and their activity is relevant for both food security and climate change. Since their discovery nearly 20 years ago, major insights have been gained into their nitrogen and carbon metabolism, growth preferences and their mechanisms of adaptation to the environment, as well as their diversity, abundance and activity in the environment. Despite significant strides forward through the cultivation of novel organisms and omics-based approaches, there are still many knowledge gaps on their metabolism and the mechanisms which enable them to adapt to the environment. Ammonia oxidising microorganisms are typically considered metabolically streamlined and highly specialised. Here we review the physiology of ammonia oxidising archaea, with focus on aspects of metabolic versatility and regulation, and discuss these traits in the context of nitrifier ecology.
Topics: Archaea; Nitrification; Ammonia; Nitrogen Cycle; Oxidation-Reduction; Soil Microbiology
PubMed: 37452095
DOI: 10.1038/s41396-023-01467-0 -
Simultaneous Anaerobic and Aerobic Ammonia and Methane Oxidation under Oxygen Limitation Conditions.Applied and Environmental Microbiology Jun 2021Methane and ammonia have to be removed from wastewater treatment effluent in order to discharge it to receiving water bodies. A potential solution for this is a...
Methane and ammonia have to be removed from wastewater treatment effluent in order to discharge it to receiving water bodies. A potential solution for this is a combination of simultaneous ammonia and methane oxidation by anaerobic ammonia oxidation (anammox) bacteria and nitrite/nitrate-dependent anaerobic methane oxidation (N-damo) microorganisms. When applied, these microorganisms will be exposed to oxygen, but little is known about the effect of a low concentration of oxygen on a culture containing these microorganisms. In this study, a stable coculture containing anammox and N-damo microorganisms in a laboratory scale bioreactor was established under oxygen limitation. Membrane inlet mass spectrometry (MIMS) was used to directly measure the simultaneous activity of N-damo, anammox, and aerobic ammonia-oxidizing microorganisms. In addition, batch tests revealed that the bioreactor also harbored aerobic methanotrophs and anaerobic methanogens. Together with fluorescence hybridization (FISH) analysis and metagenomics, these results indicate that the combination of N-damo and anammox activity under the continuous supply of limiting oxygen concentrations is feasible and can be implemented for the removal of methane and ammonia from anaerobic digester effluents. Nitrogen in wastewater leads to eutrophication of the receiving water bodies, and methane is a potent greenhouse gas; it is therefore important that these are removed from wastewater. A potential solution for the simultaneous removal of nitrogenous compounds and methane is the application of a combination of nitrite/nitrate-dependent methane oxidation (N-damo) and anaerobic ammonia oxidation (annamox). In order to do so, it is important to investigate the effect of oxygen on these two anaerobic processes. In this study, we investigate the effect of a continuous oxygen supply on the activity of an anaerobic methane- and ammonia-oxidizing coculture. The findings presented in this study are important for the potential application of these two microbial processes in wastewater treatment.
Topics: Aerobiosis; Ammonia; Anaerobiosis; Archaea; Bacteria; Bioreactors; Methane; Oxidation-Reduction; Oxygen; Water Pollutants, Chemical; Water Purification
PubMed: 33893122
DOI: 10.1128/AEM.00043-21 -
Frontiers in Endocrinology 2022The homeostasis of the most important nitrogen-containing intermediates, ammonia and glutamine, is a tightly regulated process in which the gut-liver axis plays a... (Review)
Review
The homeostasis of the most important nitrogen-containing intermediates, ammonia and glutamine, is a tightly regulated process in which the gut-liver axis plays a central role. Several studies revealed that nitrogen metabolism is altered in Metabolic Dysfunction-Associated Fatty Liver Disease (MAFLD), a consensus-driven novel nomenclature for Non-Alcoholic Fatty Liver Disease (NAFLD), the most common chronic liver disease worldwide. Both increased ammonia production by gut microbiota and decreased ammonia hepatic removal due to impaired hepatic urea cycle activity or disrupted glutamine synthetase activity may contribute to hepatic ammonia accumulation underlying steatosis, which can eventually progress to hyperammonemia in more advanced stages of steatohepatitis and overt liver fibrosis. Furthermore, our group recently showed that augmented hepatic ammoniagenesis increased glutaminase activity and overexpression of the high activity glutaminase 1 isoenzyme occurs in Fatty Liver Disease. Overall, the improved knowledge of disrupted nitrogen metabolism and metabolic miscommunication between the gut and the liver suggests that the reestablishment of altered gut-liver axis nitrogenous balance is an appealing and attractive therapeutic approach to tackle Fatty Liver Disease, a growing and unmet health problem.
Topics: Humans; Non-alcoholic Fatty Liver Disease; Glutaminase; Nitrogen; Ammonia
PubMed: 36589817
DOI: 10.3389/fendo.2022.1058101 -
Seminars in Nephrology Jul 2019Ammonia metabolism has a critical role in acid-base homeostasis and in other cellular functions. Kidneys have a central role in bicarbonate generation, which occurs... (Review)
Review
Ammonia metabolism has a critical role in acid-base homeostasis and in other cellular functions. Kidneys have a central role in bicarbonate generation, which occurs through the process of net acid excretion; ammonia metabolism is the quantitatively greatest component of net acid excretion, both under basal conditions and in response to acid-base disturbances. Several recent studies have advanced our understanding substantially of the molecular mechanisms and regulation of ammonia metabolism. First, the previous paradigm that ammonia transport could be explained by passive NH diffusion and NH trapping has been advanced by the recognition that specific transport of NH and of NH by specific membrane proteins is critical to ammonia transport. Second, significant advances have been made in the understanding of the regulation of ammonia metabolism. Novel studies have shown that hyperkalemia directly inhibits ammonia metabolism, thereby leading to the metabolic acidosis present in type IV renal tubular acidosis. Other studies have shown that the proximal tubule protein NBCe1, specifically the A variant NBCe1-A, has a major role in regulating renal ammonia metabolism. Third, there are important sex differences in ammonia metabolism that involve structural and functional differences in the kidney. This review addresses these important aspects of ammonia metabolism and transport.
Topics: Acid-Base Equilibrium; Acidosis; Ammonia; Animals; Biological Transport; Homeostasis; Humans; Hyperkalemia; Kidney
PubMed: 31300094
DOI: 10.1016/j.semnephrol.2019.04.008 -
Pflugers Archiv : European Journal of... Apr 2024The disposal of ammonia, the main proton buffer in the urine, is important for acid-base homeostasis. Renal ammonia excretion is the predominant contributor to renal net... (Review)
Review
The disposal of ammonia, the main proton buffer in the urine, is important for acid-base homeostasis. Renal ammonia excretion is the predominant contributor to renal net acid excretion, both under basal condition and in response to acidosis. New insights into the mechanisms of renal ammonia production and transport have been gained in the past decades. Ammonia is the only urinary solute known to be produced in the kidney and selectively transported through the different parts of the nephron. Both molecular forms of total ammonia, NH and NH, are transported by specific proteins. Proximal tubular ammoniagenesis and the activity of these transport processes determine the eventual fate of total ammonia produced and excreted by the kidney. In this review, we summarized the state of the art of ammonia handling by the kidney and highlighted the newest processes described in the last decade.
Topics: Humans; Ammonia; Acid-Base Equilibrium; Kidney; Homeostasis; Acidosis
PubMed: 38448728
DOI: 10.1007/s00424-024-02940-1 -
The ISME Journal Jan 2022Nitrification, the oxidation of ammonia to nitrate, is an essential process in the biogeochemical nitrogen cycle. The first step of nitrification, ammonia oxidation, is...
Nitrification, the oxidation of ammonia to nitrate, is an essential process in the biogeochemical nitrogen cycle. The first step of nitrification, ammonia oxidation, is performed by three, often co-occurring guilds of chemolithoautotrophs: ammonia-oxidizing bacteria (AOB), archaea (AOA), and complete ammonia oxidizers (comammox). Substrate kinetics are considered to be a major niche-differentiating factor between these guilds, but few AOA strains have been kinetically characterized. Here, the ammonia oxidation kinetic properties of 12 AOA representing all major cultivated phylogenetic lineages were determined using microrespirometry. Members of the genus Nitrosocosmicus have the lowest affinity for both ammonia and total ammonium of any characterized AOA, and these values are similar to previously determined ammonia and total ammonium affinities of AOB. This contrasts previous assumptions that all AOA possess much higher substrate affinities than their comammox or AOB counterparts. The substrate affinity of ammonia oxidizers correlated with their cell surface area to volume ratios. In addition, kinetic measurements across a range of pH values supports the hypothesis that-like for AOB-ammonia and not ammonium is the substrate for the ammonia monooxygenase enzyme of AOA and comammox. Together, these data will facilitate predictions and interpretation of ammonia oxidizer community structures and provide a robust basis for establishing testable hypotheses on competition between AOB, AOA, and comammox.
Topics: Ammonia; Archaea; Bacteria; Nitrification; Oxidation-Reduction; Phylogeny; Soil Microbiology
PubMed: 34316016
DOI: 10.1038/s41396-021-01064-z -
Physiological Research Aug 2020Histidine (HIS) is an essential amino acid investigated for therapy of various diseases, used for tissue protection in transplantation and cardiac surgery, and as a... (Review)
Review
Histidine (HIS) is an essential amino acid investigated for therapy of various diseases, used for tissue protection in transplantation and cardiac surgery, and as a supplement to increase muscle performance. The data presented in the review show that HIS administration may increase ammonia and affect the level of several amino acids. The most common are increased levels of alanine, glutamine, and glutamate and decreased levels of glycine and branched-chain amino acids (BCAA, valine, leucine, and isoleucine). The suggested pathogenic mechanisms include increased flux of HIS through HIS degradation pathway (increases in ammonia and glutamate), increased ammonia detoxification to glutamine and exchange of the BCAA with glutamine via L-transporter system in muscles (increase in glutamine and decrease in BCAA), and tetrahydrofolate depletion (decrease in glycine). Increased alanine concentration is explained by enhanced synthesis in extrahepatic tissues and impaired transamination in the liver. Increased ammonia and glutamine and decreased BCAA levels in HIS-treated subjects indicate that HIS supplementation is inappropriate in patients with liver injury. The studies investigating the possibilities to elevate carnosine (beta-alanyl-L-histidine) content in muscles show positive effects of beta-alanine and inconsistent effects of HIS supplementation. Several studies demonstrate HIS depletion due to enhanced availability of methionine, glutamine, or beta-alanine.
Topics: Amino Acids; Ammonia; Animals; Dietary Supplements; Histidine; Humans; Liver; Muscle, Skeletal
PubMed: 32584129
DOI: 10.33549/physiolres.934449 -
International Journal of Environmental... Mar 2022Exposure to hazardous chemicals released during hairdressing activities from hair care products puts hairdressers at risk of adverse health effects. Safety assessments... (Review)
Review
INTRODUCTION
Exposure to hazardous chemicals released during hairdressing activities from hair care products puts hairdressers at risk of adverse health effects. Safety assessments of hair products are mainly focused on consumers, but exposure for professional hairdressers might be substantially higher.
OBJECTIVE
To identify and assess available research data on inhalation exposures of professional hairdressers.
METHODS
A systematic search of studies between 1 January 2000 and 30 April 2021 was performed in Medline, Embase, Web of Science and in Cochrane registry, toxicological dossiers of the Scientific Committee on Consumer Safety (SCCS) of the European Commission as well as the German MAK Commission. Studies reporting quantitative data on airborne concentrations of chemicals in the hairdresser's workplace were considered. The outcome was an airborne concentration of chemicals in the working environment, which was compared, when possible, with current occupational exposure limits (OEL) or guidance levels.
RESULTS
In total, 23 studies performed in 14 countries were included. The average number of hairdressing salons per study was 22 (range 1-62). Chemicals most frequently measured were formaldehyde ( = 8), ammonia ( = 5), total volatile organic compounds (TVOC) ( = 5), and toluene ( = 4). More than fifty other chemicals were measured in one to three studies, including various aromatic and aliphatic organic solvents, hydrogen peroxide, persulfate, and particulate matter. Most studies reported environmental air concentrations, while personal exposure was measured only in seven studies. The measured air concentrations of formaldehyde, ammonia, and TVOC exceeded OEL or guidance values in some studies. There was large variability in measuring conditions and reported air concentrations differed strongly within and between studies.
CONCLUSION
Hairdressers are exposed to a wide spectrum of hazardous chemicals, often simultaneously. Airborne concentrations of pollutants depend on salon characteristics such as ventilation and the number of customers but also on used products that are often country- or client-specific. For exposure to formaldehyde, ammonia, and TVOC exceeding OELs or guidance values for indoor air was observed. Therefore, occupational exposure should be taken into account by safety regulations for hair care products.
Topics: Ammonia; Formaldehyde; Hair Preparations; Hazardous Substances; Humans; Occupational Exposure; Volatile Organic Compounds
PubMed: 35409860
DOI: 10.3390/ijerph19074176 -
The ISME Journal Oct 2023The ecophysiology of complete ammonia-oxidizing bacteria (CMX) of the genus Nitrospira and their widespread occurrence in groundwater suggests that CMX bacteria have a...
The ecophysiology of complete ammonia-oxidizing bacteria (CMX) of the genus Nitrospira and their widespread occurrence in groundwater suggests that CMX bacteria have a competitive advantage over ammonia-oxidizing bacteria (AOB) and archaea (AOA) in these environments. However, the specific contribution of their activity to nitrification processes has remained unclear. We aimed to disentangle the contribution of CMX, AOA and AOB to nitrification and to identify the environmental drivers of their niche differentiation at different levels of ammonium and oxygen in oligotrophic carbonate rock aquifers. CMX ammonia monooxygenase sub-unit A (amoA) genes accounted on average for 16 to 75% of the total groundwater amoA genes detected. Nitrification rates were positively correlated to CMX clade A associated phylotypes and AOB affiliated with Nitrosomonas ureae. Short-term incubations amended with the nitrification inhibitors allylthiourea and chlorate suggested that AOB contributed a large fraction to overall ammonia oxidation, while metaproteomics analysis confirmed an active role of CMX in both ammonia and nitrite oxidation. Ecophysiological niche differentiation of CMX clades A and B, AOB and AOA was linked to their requirements for ammonium, oxygen tolerance, and metabolic versatility. Our results demonstrate that despite numerical predominance of CMX, the first step of nitrification in oligotrophic groundwater appears to be primarily governed by AOB. Higher growth yields at lower ammonia turnover rates and energy derived from nitrite oxidation most likely enable CMX to maintain consistently high populations.
Topics: Nitrification; Ammonia; Oxidation-Reduction; Soil Microbiology; Bacteria; Archaea; Ammonium Compounds; Groundwater; Oxygen; Phylogeny
PubMed: 37422599
DOI: 10.1038/s41396-023-01471-4