Auflistung nach Autor:in "Lenz, Markus"
Gerade angezeigt 1 - 20 von 56
- Treffer pro Seite
- Sortieroptionen
Publikation An artificial metalloenzyme for carbene transfer based on a biotinylated dirhodium anchored within streptavidin(Royal Society of Chemistry, 04/2018) Zhao, Jingming; Bachmann, Daniel G.; Lenz, Markus; Gillingham, Dennis G.; Ward, Thomas R.We report on artificial metalloenzymes that incorporate a biotinylated dirhodium core embedded within engineered streptavidin (Sav hereafter) variants. The resulting biohybrid catalyzes the carbene insertion in C–H bonds and olefins. Chemical- and genetic optimization allows to modulate the catalytic activity of the artificial metalloenzymes that are shown to be active in the periplasm of E. coli (up to 20 turnovers).01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Analysis of bioavailability and induction of glutathione peroxidase by dietary nanoelemental, organic and inorganic selenium(MDPI, 15.03.2021) Lenz, Markus; Ringuet, Mitchell; Hunne, Billie; Bravo, David; Furness, JohnDietary organic selenium (Se) is commonly utilized to increase formation of selenoproteins, including the major antioxidant protein, glutathione peroxidase (GPx). Inorganic Se salts, such as sodium selenite, are also incorporated into selenoproteins, and there is evidence that nanoelemental Se added to the diet may also be effective. We conducted two trials, the first investigated inorganic Se (selenite), organic Se (L-selenomethionine) and nanoelemental Se, in conventional mice. Their bioavailability and effectiveness to increase GPx activity were examined. The second trial focused on determining the mechanism by which dietary Se is incorporated into tissue, utilising both conventional and germ-free (GF) mice. Mice were fed a diet with minimal Se, 0.018 parts per million (ppm), and diets with Se supplementation, to achieve 0.07, 0.15, 0.3 and 1.7 ppm Se, for 5 weeks (first trial). Mass spectrometry, Western blotting and enzymatic assays were used to investigate bioavailability, protein levels and GPx activity in fresh frozen tissue (liver, ileum, plasma, muscle and feces) from the Se fed animals. Inorganic, organic and nanoelemental Se were all effectively incorporated into tissues. The high Se diet (1.7 ppm) resulted in the highest Se levels in all tissues and plasma, independent of the Se source. Interestingly, despite being ~11 to ~25 times less concentrated than the high Se, the lower Se diets (0.07; 0.15) resulted in comparably high Se levels in liver, ileum and plasma for all Se sources. GPx protein levels and enzyme activity were significantly increased by each diet, relative to control. We hypothesised that bacteria may be a vector for the conversion of nanoelemental Se, perhaps in exchange for S in sulphate metabolising bacteria. We therefore investigated Se incorporation from low sulphate diets and in GF mice. All forms of selenium were bioavailable and similarly significantly increased the antioxidant capability of GPx in the intestine and liver of GF mice and mice with sulphate free diets. Se from nanoelemental Se resulted in similar tissue levels to inorganic and organic sources in germ free mice. Thus, endogenous mechanisms, not dependent on bacteria, reduce nanoelemental Se to the metabolite selenide that is then converted to selenophosphate, synthesised to selenocysteine, and incorporated into selenoproteins. In particular, the similar efficacy of nanoelemental Se in comparison to organic Se in both trials is important in the view of the currently limited cheap sources of Se.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Antimony retention and release from drained and waterlogged shooting range soil under field conditions(Elsevier, 09/2015) Hockmann, Kerstin; Tandy, Susan; Lenz, Markus; Reiser, Rene; Conesa, Hector; Keller, Martin; Studer, Björn; Schulin, RainerMany soils polluted by antimony (Sb) are subject to fluctuating waterlogging conditions; yet, little is known about how these affect the mobility of this toxic element under field conditions. Here, we compared Sb leaching from a calcareous shooting range soil under drained and waterlogged conditions using four large outdoor lysimeters. After monitoring the leachate samples taken at bi-weekly intervals for >1.5 years under drained conditions, two of the lysimeters were subjected to waterlogging with a water table fluctuating according to natural rainfall water infiltration. Antimony leachate concentrations under drained conditions showed a strong seasonal fluctuation between 110 μg L−1 in summer and <40 μg L−1 in winter, which closely correlated with fluctuations in dissolved organic carbon (DOC) concentrations. With the development of anaerobic conditions upon waterlogging, Sb in leachate decreased to 2–5 μg L−1 Sb and remained stable at this level. Antimony speciation measurements in soil solution indicated that this decrease in Sb(V) concentrations was attributable to the reduction of Sb(V) to Sb(III) and the stronger sorption affinity of the latter to iron (Fe) (hydr)oxide phases. Our results demonstrate the importance of considering seasonal and waterlogging effects in the assessment of the risks from Sb-contaminated sites.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Are degrading OPV materials still sustainable?(2015) Zimmermann, Yannick; Brun, Nadja; Hengevoss, Dirk; Corvini, Philippe; Fent, Karl; Hugi, Christoph; Lenz, Markus06 - PräsentationPublikation Arsenic Mobilization from Historically Contaminated Mining Soils in a Continuously Operated Bioreactor: Implications for Risk Assessment(Taylor & Francis, 2016) Rajpert, Liwia; Kolvenbach, Boris; Ammann, Erik; Hockmann, Kerstin; Nachtegaal, Maarten; Eiche, Elisabeth; Schäffer, Andreas; Corvini, Philippe; Sklodowska, Aleksandra; Lenz, MarkusConcentrations of soil arsenic (As) in the vicinity of the former Złoty Stok gold mine (Lower Silesia, southwest Poland) exceed 1000 μg g–1 in the area, posing an inherent threat to neighboring bodies of water. This study investigated continuous As mobilization under reducing conditions for more than 3 months. In particular, the capacity of autochthonic microflora that live on natural organic matter as the sole carbon/electron source for mobilizing As was assessed. A biphasic mobilization of As was observed. In the first two months, As mobilization was mainly conferred by Mn dissolution despite the prevalence of Fe (0.1 wt % vs 5.4 for Mn and Fe, respectively) as indicated by multiple regression analysis. Thereafter, the sudden increase in aqueous As[III] (up to 2400 μg L–1) was attributed to an almost quintupling of the autochthonic dissimilatory As-reducing community (quantitative polymerase chain reaction). The aqueous speciation influenced by microbial activity led to a reduction of solid phase As species (X-ray absorption fine structure spectroscopy) and a change in the elemental composition of As hotspots (micro X-ray fluorescence mapping). The depletion of most natural dissolved organic matter and the fact that an extensive mobilization of As[III] occurred after two months raises concerns about the long-term stability of historically As-contaminated sites.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Biodegradation of sulfamethoxazole by a bacterial consortium of Achromobacter denitrificans PR1 and Leucobacter sp. GP(Springer, 12/2018) Reis, Ana C.; Cvancarova Småstuen, M.; Liu, Ying; Lenz, Markus; Hettich, Timm; Kolvenbach, Boris; Corvini, Philippe; Nunes, Olga C.In the last decade, biological degradation and mineralization of antibiotics have been increasingly reported feats of environmental bacteria. The most extensively described example is that of sulfonamides that can be degraded by several members of Actinobacteria and Proteobacteria. Previously, we reported sulfamethoxazole (SMX) degradation and partial mineralization by Achromobacter denitrificans strain PR1, isolated from activated sludge. However, further studies revealed an apparent instability of this metabolic trait in this strain. Here, we investigated this instability and describe the finding of a low-abundance and slow-growing actinobacterium, thriving only in co-culture with strain PR1. This organism, named GP, shared highest 16S rRNA gene sequence similarity (94.6–96.9%) with the type strains of validly described species of the genus Leucobacter. This microbial consortium was found to harbor a homolog to the sulfonamide monooxygenase gene (sadA) also found in other sulfonamide-degrading bacteria. This gene is overexpressed in the presence of the antibiotic, and evidence suggests that it codes for a group D flavin monooxygenase responsible for the ipso-hydroxylation of SMX. Additional side reactions were also detected comprising an NIH shift and a Baeyer–Villiger rearrangement, which indicate an inefficient biological transformation of these antibiotics in the environment. This work contributes to further our knowledge in the degradation of this ubiquitous micropollutant by environmental bacteria.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Biodeterioration affecting efficiency and lifetime of plastic-based photovoltaics(Elsevier, 16.09.2020) Schmidt, Felix; Lenz, Markus; Schaeffer, Andreas; Zimmermann, Yannick; Alves dos Reis Benatto, Gisele; Kolvenbach, Boris; Krebs, FrederikThe low environmental impact of electricity generation using solar cells crucially depends on high energy-conversion efficiencies, long lifetimes and a minimal energy and material demand during production. Emerging thin-film photovoltaics such as perovskites on plastic substrates could hold promise to fulfil all these requirements. Under real-world operating conditions photovoltaic operation is challenged by biological stressors, which have not been incorporated for evaluation in any test. Such stressors cause biodeterioration, which impairs diverse, apparently inert materials such as rock, glass and steel and therefore could significantly affect the function and stability of plastic-based solar cells. Given that different photovoltaic technologies commonly use similar materials, the biodeterioration mechanisms reviewed here may possibly affect the efficiency and lifetimes of several technologies, if they occur sufficiently fast (during the expected lifetime of photovoltaics). Once the physical integrity of uppermost module layers is challenged by biofilm growth microbially mediated dissolution and precipitation reactions of photovoltaic functional materials are very likely to occur. The biodeterioration of substrates and seals also represents emission points for the release of potentially harmful photovoltaic constituents to the environment01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Bioleaching and toxicity of metallurgical wastes(Elsevier, 09.09.2020) Potysz, Anna; Lenz, Markus; Hedwig, SebastianMetallurgical wastes contain metals that are unrecovered during industrial processing. The disposal of these wastes is technically difficult due to the potential release of metals through weathering. Therefore, alternative management methods are currently sought. The high leaching susceptibility of these wastes combined with the need for alternative sources of rare and critical metals creates a need for residual element recovery. This study evaluated the leaching potential of lead matte and copper slag through chemical mineral acid leaching as well as indirect bioleaching with organic acids and direct bioleaching using Acidithiobacillus thiooxidans. The leaching efficiency of these acids was compared based on different normality equivalents. Additionally, the effects of pulp density (1–10%) and extraction time (24–48 h) were assessed. Slag toxicity was assessed with a germination test in concentrated and diluted leachates using Brassica juncea. The results demonstrated that copper slag is particularly suitable for chemical treatment because as much as 91 wt.% Cu and 85 wt.% Zn or 70 wt.% Cu and 81 wt.% Zn were extracted using HNO3 or bacterial leaching, respectively. The residual slag was characterized by significant metal depletion and the presence of gypsum, rendering it more suitable for further use or disposal. Lead matte released 65 wt.% Cu and 8 wt.% Zn using mineral acid leaching while 70 wt.% Cu and 12 wt.% Zn were released using bacterial leaching. Further process optimization is needed for lead matte to generate residue depletion in toxic metals. Toxicity assessment showed toxic characteristics in metal-loaded leachates originating from waste treatment that inhibited germination rates and root development.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Biomineralisierung von Selen: Von Abwasserbehandlung zu Ressourcen-Wiedergewinnung(2015) Lenz, Markus; Kolvenbach, Boris; Corvini, Philippe06 - PräsentationPublikation Biotechnological strategies for the recovery of valuable and critical raw materials from waste electrical and electronic equipment (WEEE) – A review(Elsevier, 01/2019) Işıldar, Arda; Lenz, Markus; Du Laing, Gijs; Cesaro, Alessandra; Marra, Alessandra; Panda, Sandeep; Akcil, Ata; Kucuker, Mehmet Ali; Kuchta, Kerstin; van Hullebusch, Eric D.Critical raw materials (CRMs) are essential in the development of novel high-tech applications. They are essential in sustainable materials and green technologies, including renewable energy, emissionfree electric vehicles and energy-efficient lighting. However, the sustainable supply of CRMs is a major concern. Recycling end-of-life devices is an integral element of the CRMs supply policy of many countries. Waste electrical and electronic equipment (WEEE) is an important secondary source of CRMs. Currently, pyrometallurgical processes are used to recycle metals from WEEE. These processes are deemed imperfect, energy-intensive and non-selective towards CRMs. Biotechnologies are a promising alternative to the current industrial best available technologies (BAT). In this review, we present the current frontiers in CRMs recovery from WEEE using biotechnology, the biochemical fundamentals of these bio-based technologies and discuss recent research and development (R&D) activities. These technologies encompass biologically induced leaching (bioleaching) from various matrices,biomass-induced sorption (biosorption), and bioelectrochemical systems (BES).01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Biotechnologies for Critical Raw Material Recovery from Primary and Secondary Sources: R&D Priorities and Future Perspectives(Elsevier, 25.01.2015) Hennebel, Tom; Boon, Nico; Maes, Synthia; Lenz, MarkusEurope is confronted with an increasing supply risk of critical raw materials. These can be defined as materials of which the risks of supply shortage and their impacts on the economy are higher compared to most of other raw materials. Within the framework of the EU Innovation Partnership on raw materials Initiative, a list of 14 critical materials was defined, including some bulk metals, industrial minerals, the platinum group metals and rare earth elements. To tackle the supply risk challenge, innovation is required with respect to sustainable primary mining, substitution of critical metals, and urban mining. In these three categories, biometallurgy can play a crucial role. Indeed, microbe-metal interactions have been successfully applied on full scale to win materials from primary sources, but are not sufficiently explored for metal recovery or recycling. On the one hand, this article gives an overview of the microbial strategies that are currently applied on full scale for biomining; on the other hand it identifies technologies, currently developed in the laboratory, which have a perspective for large scale metal recovery and the needs and challenges on which bio-metallurgical research should focus to achieve this ambitious goal.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Can iron plaque affect Sb(III) and Sb(V) uptake by plants under hydroponic conditions(Elsevier, 04/2018) Ji, Ying; Vollenweider, Pierre; Lenz, Markus; Schulin, Rainer; Tandy, SusanAntimony (Sb) contamination of soils is of concern due to human activities such as recycling of Sb containing Pb acid batteries, shooting and mining. However Sb uptake by plants is poorly documented, especially when plants are growing on waterlogged soils and iron plaques form on their roots. The effect of iron plaques on Sb uptake has been investigated in rice, but not so far in other plants. Here, rye, ryegrass, wheat and meadow fescue were induced to form iron plaques and then exposed to antimonite (Sb(III)) or antimonate (Sb(V)) under hydroponic conditions. In the Sb(III) treatment, although iron plaques adsorbed Sb(III), this did not affect root and shoot Sb concentrations of plants. In the Sb(V) treatment, iron plaques adsorbed Sb(V) to a lesser extent than for Sb(III), although it was still significant in all plants but wheat. Iron treatments also significantly increased root Sb concentrations of fescue while they significantly decreased shoot Sb concentrations in rye, ryegrass and fescue. This may be due to other factors as well as antimony adsorption to iron plaques.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Characterization of heavy metal toxicity in some plants and microorganisms—A preliminary approach for environmental bioremediation(Elsevier, 13.01.2020) Diaconu, Mariana; Corvini, Philippe; Lenz, Markus01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Circularity and environmental sustainability of organic and printed electronics(Jenny Stanford Publishing, 2024) Le Blévennec, Kévin; Hengevoss, Dirk; Zimmermann, Yannick-Serge; Brun, Nadja; Hugi, Christoph; Lenz, Markus; Corvini, Philippe; Fent, Karl; Nisato, Giovanni; Lupo, Donald; Rudolf, SimoneIn this chapter, the possible role and impact of organic and printed electronics (OPE) in a transition toward a circular economy and more sustainable society will be discussed. The learning targets are twofold: first, understanding main environmental issues associated with the emerging field of OPE, and second, identifying, through a systemic perspective, the enabling potential of these technologies.04A - Beitrag SammelbandPublikation Crystallographic, optical, and electronic properties of the Cs2AgBi1–xInxBr6 double perovskite. Understanding the fundamental photovoltaic efficiency challenges(American Chemical Society, 19.02.2021) Lenz, Markus; Schade, Laura; Mahesh, Suhas; Volonakis, George; Zacharias, Marios; Wenger, Bernard; Schmidt, Felix; Kesava, Sameer Vajjala; Prabhakaran, Dharmalingam; Abdi-Jalebi, Mojtaba; Longo, Giulia; Radaelli, Paolo; Snaith, Henry; Giustino, FelicianoWe present a crystallographic and optoelectronic study of the double perovskite Cs2AgBi1–xInxBr6. From structural characterization we determine that the indium cation shrinks the lattice and shifts the cubic-to-tetragonal phase transition point to lower temperatures. The absorption onset is shifted to shorter wavelengths upon increasing the indium content, leading to wider band gaps, which we rationalize through first-principles band structure calculations. Despite the unfavorable band gap shift, we observe an enhancement in the steady-state photoluminescence intensity, and n-i-p photovoltaic devices present short-circuit current greater than that of neat Cs2AgBiBr6 devices. In order to evaluate the prospects of this material as a solar absorber, we combine accurate absorption measurements with thermodynamic modeling and identify the fundamental limitations of this system. Provided radiative efficiency can be increased and the choice of charge extraction layers are specifically improved, this material could prove to be a useful wide band gap solar absorber.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Deterioration of sandstones: Insights from experimental weathering in acidic, neutral and biotic solutions with Acidithiobacillus thiooxidans(Elsevier, 24.02.2020) Potysz, Anna; Schmidt, Felix; Lenz, Markus; Bartz, Wojciech; Zboińska, KatarzynaThe susceptibility of sandstones to deteriorative factors when used for construction requires detailed experimental evaluation. This study investigated the (bio)weathering behaviour of Lower-Silesian Cretaceous sandstones (quartz arenites) to quantify the deteriorative effect of bacterium Acidithiobacillus thiooxidans. For controls, ultrapure water (in undersaturated conditions) and sterile acidic medium (in abiotic acidic conditions pH 2.5) were used. Sandstone exposure to A. thiooxidans mimicked the extremely acidic conditions (pH up to 0.9) that may develop under long-term weathering, which promote microbial activity and acidic metabolite production. Element release was assessed using triple quadrupole inductively coupled plasma mass spectrometry (QQQ-ICP-MS) and identifying potential element donor minerals through scanning electron microscopy, coupled with energy dispersive spectrometer (SEM-EDS). The results demonstrated that sandstones were relatively susceptible to weathering, especially when exposed to aggressive acidic conditions, where the presence of bacteria apparently acts as an accelerating factor in deterioration. Based on Si release, sandstone degradation under biotic conditions was 0.27% within 86 days, whereas the dissolution achieved in ultrapure water did not exceed 0.02%. A highly pronounced weathering feature observed on sandstones was the dissolution of goethite and/or kaolinite cement, whereas quartz was less susceptible to weathering under the conditions studied. Bioweathering investigations may help solve deterioration issues in sandstone building materials.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Ecotoxicity attenuation by acid-resistant nanofiltration in scandium recovery from TiO2 production waste(Elsevier, 2023) Fekete-Kertész, Ildikó; Stirling, Tamás; Vaszita, Emese; Berkl, Zsófia; Farkas, Éva; Hedwig, Sebastian; Remmen, Kirsten; Lenz, Markus; Molnár, Mónika; Feigl, Viktória01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Effects of barium on the pathways of anaerobic digestion(Elsevier, 2019) Wyman, Valentina; Lenz, Markus; Serrano, AntonioThe sufficient presence of trace elements (TE) is essential for anaerobic digestion. Barium (Ba) is considered a non-essential trace element that can be collaterally added to digesters as part of low-cost trace element sources or because of its presence in some feedstocks, such as crude glycerol. In the present study, the impact of Ba supplementation (2–2000 mg/L) on each stage of the anaerobic digestion (AD) process was evaluated using pure substrates (i.e., cellulose, glucose, a mixture of volatile fatty acids, sodium acetate and hydrogen) as well as a complex substrate (i.e., dried green fodder). Hydrolytic activity was affected at dosages higher than 200 mg Ba/L, whereas cellulose degradation was completely inhibited at 2000 mg Ba/L. The negative effects of the addition of Ba to methane production were observed only in the hydrolytic activity, and no effects were detected at any barium dosage in the subsequent anaerobic steps. Because Ba does not have a reported role as a cofactor of enzymes, this response could have been due to a direct inhibitory effect, a variation in the bioavailability of other trace elements, or even the availability of CO2/SO4 through precipitation as Ba-carbonates and sulphates. The results showed that the addition of Ba modified the chemical equilibrium of the studied system by varying the soluble concentration of some TEs and therefore their bioavailability. The highest variation was detected in the soluble concentration of zinc, which increased as the amount of Ba increased. Although little research has shown that Ba has some utility in anaerobic processes, its addition must be carefully monitored to avoid an undesirable modification of the chemical equilibrium in the system.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Environmental aspects of printable and organic electronics (POE)(Pan Stanford Publishing, 04/2016) Hengevoss, Dirk; Zimmermann, Yannick; Brun, Nadja; Hugi, Christoph; Lenz, Markus; Corvini, Philippe; Fent, Karl; Nisato, Giovanni; Lupo, Donald; Ganz, Simone04A - Beitrag SammelbandPublikation Environmental selenium volatilization is possibly conferred by promiscuous reactions of the sulfur metabolism(Elsevier, 2023) Liu, Ying; Schäffer, Andreas; Martinez, Mathieu; Lenz, MarkusSelenium deficiency affects many million people worldwide and volatilization of biogenically methylated selenium species to the atmosphere may limit Se entering the food chain. However, there is very little systematic data on volatilization at nanomolar concentrations prevalent in pristine natural environments. Pseudomonas tolaasii cultures efficiently methylated Se at these concentrations. Nearly perfect linear correlations between the spiked Se concentrations and Dimethylselenide, Dimethyldiselenide, Dimethylselenylsulfide and 2-hydroxy-3-(methylselanyl)propanoic acid were observed up to 80 nM. The efficiency of methylation increased linearly with increasing initial Se concentration, arguing that the enzymes involved are not constitutive, but methylation proceeds promiscuously via pathways of S methylation. From the ratio of all methylated Se and S species, one can conclude that between 0.30% and 3.48% of atoms were Se promiscuously methylated at such low concentrations. At concentrations higher than 640 nM (∼50 μg/L) a steep increase in methylation and volatilization was observed, which suggested the induction of specific enzymes. Promiscuous methylation at low environmental concentrations calls into question that view that methylated Se in the atmosphere is a result of a purposeful Se metabolism serving detoxification. Rather, the concentrations of methylated Se in the atmosphere may be “coincidental” i.e., determined by the activity of S cycling microorganisms. Further, a steep increase in methylation efficiency when surpassing a certain threshold concentration (here ∼50 μg/L) calls into question that natural methylation can be estimated from high Se spikes in laboratory systems, yet highlights the possibility of using bacterial methylation as an effective remediation strategy for media higher concentrated in Se. © 2023 The Authors01A - Beitrag in wissenschaftlicher Zeitschrift
- «
- 1 (current)
- 2
- 3
- »