A5061289049- Pharmaceutical and Antibiotic Environmental Impacts
- Marine and coastal ecosystems
- Water Treatment and Disinfection
- Microbial bioremediation and biosurfactants
- Metabolomics and Mass Spectrometry Studies
- Chemical Reactions and Isotopes
- Isotope Analysis in Ecology
- Metal-Catalyzed Oxygenation Mechanisms
- Radioactive element chemistry and processing
- Water Quality Monitoring and Analysis
- Toxic Organic Pollutants Impact
- Groundwater and Isotope Geochemistry
- Catalytic Processes in Materials Science
- Electrochemical Analysis and Applications
- Mitochondrial Function and Pathology
- Analytical chemistry methods development
- Metabolism and Genetic Disorders
- High Altitude and Hypoxia
- Mass Spectrometry Techniques and Applications
- Environmental Chemistry and Analysis
- Chemical Analysis and Environmental Impact
- Microbial metabolism and enzyme function
- Ammonia Synthesis and Nitrogen Reduction
- Microbial Fuel Cells and Bioremediation
- Eicosanoids and Hypertension Pharmacology
University of Basel
2020-2025
University of Vienna
2024-2025
ETH Zurich
2012-2022
Swiss Federal Institute of Aquatic Science and Technology
2012-2022
University of Minnesota
2017-2020
University of Minnesota System
2018-2020
Minneapolis Institute of Arts
2018-2020
Quaternary ammonium compounds were found at substantial levels in wastewater effluents and sediment samples with treatment practices usage rates determining their environmental prevalence.
Rieske dioxygenases catalyze the initial steps in hydroxylation of aromatic compounds and are critical for metabolism xenobiotic substances. Because substrates do not bind to mononuclear non-heme FeII center, elementary leading O2 activation substrate difficult delineate, thus making it challenging rationalize divergent observations on enzyme mechanisms, reactivity, specificity. Here, we show nitrobenzene dioxygenase, a dioxygenase capable transforming nitroarenes nitrite substituted...
Oxygen isotope ratios of O2 are important tracers for assessing biological activity in biogeochemical processes aquatic environments. In fact, changes the 18O/16O and 17O/16O have been successfully implemented as measures quantifying photosynthetic production respiration. Despite evidence light-dependent consumption sunlit surface waters, however, photochemical loss so far neglected stable isotope-based evaluation oxygen cycling. Here, we established magnitude O fractionation abiotic...
Isotopic fractionation of O2 is an important tracer for estimating primary production in aquatic environments because it helps to disentangle the respective contributions from production, consumption, and gas-exchange. Isotope-based methods productivity typically involve measurements either only 18O/16O ratios or, case triple oxygen isotope approaches, also 17O/16O ratios. Aerobic respiration generally assumed be process consuming O2, with a constant value O-isotopic fractionation, expressed...
Abstract. Stable isotope analysis of O2 has emerged as a valuable tool to study dynamics at various environmental scales, from molecular mechanisms ecosystem processes. Despite its utility, there is lack fundamental understanding the large variability observed in isotopic fractionation environment- and even enzyme-level. To expand our knowledge on potential causes this variability, we determined 18O-kinetic effects (KIEs) across broad range O2-consuming enzymes. The studied enzymes included...
Compound-specific isotope analysis (CSIA) is a promising approach for tracking biotransformation of organic pollutants, but fractionation associated with aromatic oxygenations only poorly understood. We investigated the dioxygenation series nitroaromatic compounds to corresponding catechols by two enzymes, namely, nitrobenzene and 2-nitrotoluene dioxygenase (NBDO 2NTDO) elucidate enzyme- substrate-specificity C H fractionation. While apparent (13)C- (2)H-kinetic effects nitrobenzene,...
Dioxygenation of aromatic rings is frequently the initial step biodegradation organic subsurface pollutants. This process can be tracked by compound-specific isotope analysis to assess extent contaminant transformation, but corresponding effects, especially for dioxygenation N-substituted, contaminants, are not well understood. We investigated C and N fractionation associated with aniline diphenylamine using pure cultures Burkholderia sp. strain JS667, which biodegrade both compounds, each a...
We investigated the mechanisms and isotope effects associated with N-dealkylation N-atom oxidation of substituted N-methyl- N,N-dimethylanilines to identify fractionation trends for assessment oxidations aromatic N-alkyl moieties by compound-specific analysis (CSIA). In laboratory batch model systems, we determined C, H, N enrichment factors MnO(2) horseradish peroxidase (HRP), derived apparent (13)C-, (2)H-, (15)N-kinetic (AKIEs), characterized reaction products. The pathway leading radical...
Although diclofenac ranks among the most frequently detected pharmaceuticals in urban water cycle, its environmental transformation reactions remain imperfectly understood. Biodegradation-induced changes 15N/14N ratios (εN = −7.1‰ ± 0.4‰) have indicated that compound-specific isotope analysis (CSIA) may detect degradation. This singular observation warrants exploration for further reactions. The present study surveys carbon and nitrogen fractionation other engineered of diclofenac. While was...
Oxygenation of aromatic rings is a frequent initial step in the biodegradation persistent contaminants, and accompanying isotope fractionation increasingly used to assess extent transformation environment. Here, we systematically investigated dioxygenation two nitroaromatic compounds (nitrobenzene 2-nitrotoluene) by nitrobenzene dioxygenase (NBDO) obtain insights into factors governing its C, H, N fractionation. Experiments were carried out at different levels biological complexity from...
The assessment of oxidative pollutant biotransformation by compound specific isotope analysis (CSIA) is often complicated the variability kinetic effects associated with carbon oxygenation in enzymatic reactions. Here, we illustrate how information about kinetics biocatalysis flavin-dependent monooxygenases (FMOs) enables one to assess if CSIA could be applied for tracking contaminant biodegradation. In "cautious" FMOs, which form reactive flavin (hydro)peroxide species after substrate...
Ionic liquids (ILs) are a new class of solvents expected to be used increasingly by the chemical industry in coming years. Given their slow biodegradation and limited sorption affinities, IL cations have high potential reach aquatic environments. We investigated fate ILs sunlit surface water determining direct indirect photochemical transformation rates imidazolium, pyridinium, pyrrolidinium, piperidinium cations. The photodegradation all was faster solutions containing dissolved organic...
Oxygen isotope fractionation of molecular O2 is an important process for the study aerobic metabolism, photosynthesis, and formation reactive oxygen species. The latter particular interest investigating mechanism enzyme-catalyzed reactions, such as oxygenation organic pollutants, which detoxification mechanism.We developed a simple method to measure δ(18) O values dissolved in small samples using automated split injection gas chromatography coupled ratio mass spectrometry (GC/IRMS). After...
Assessing the pathways and rates of organic pollutant transformation in environment is a major challenge due to co-occurring transport degradation processes. Measuring changes stable isotope ratios (e.g. (13)C/(12)C, (2)H/(1)H, (15)N/(14)N) individual compounds by compound-specific analysis (CSIA) makes it possible identify without explicit need quantify concentration dynamics. The so-called fractionation observed an related effects (bio)chemical reactions enables one characterize even if...
Ionic liquid cations can be removed from contaminated source water by various UV-based advanced oxidation processes due to efficient reactions with hydroxyl and sulfate radicals.
Monitoring changes in stable oxygen isotope ratios molecular allows for studying many fundamental processes bio(geo)chemistry and environmental sciences. While the measurement of [Formula: see text]O/[Formula: text]O text] gaseous samples can be carried out conveniently from extracting moderately small aqueous analyses by continuous-flow ratio mass spectrometry (CF-IRMS), signatures, text]O, could overestimated more than 6[Formula: because interferences argon air. Here, we systematically...
Oxygen isotope ratios of O2 are important tracers for assessing biological activity in biogeochemical processes aquatic environments. In fact, changes 18O/16 O and 17O/16 have been successfully implemented as measures quantifying photosynthetic production respiration. Despite evidence light-dependent consumption sunlit surface waters, however, photochemical loss so far neglected the stable isotope-based evaluation oxygen cycling. Here, we established magnitude fractionation abiotic...
Oxygen isotope ratios of O2 are important tracers for assessing biological activity in biogeochemical processes aquatic environments. In fact, changes 18O/16 O and 17O/16 have been successfully implemented as measures quantifying photosynthetic production respiration. Despite evidence light-dependent consumption sunlit surface waters, however, photochemical loss so far neglected the stable isotope-based evaluation oxygen cycling. Here, we established magnitude fractionation abiotic...
Rationale Stable isotope analysis of O 2 is a valuable tool to identify ‐consuming processes in the environment; however, reference materials for are lacking. Consequently, one‐point calibration with from ambient air often applied, which can lead substantial measurement uncertainties. Our goals were develop simple multipoint isotope‐ratio approach and determine errors δ 18 17 values associated calibration. Methods We produced photosynthetically extracted spinach thylakoids source waters −56‰...