Filtern
Erscheinungsjahr
- 2020 (59) (entfernen)
Dokumenttyp
- Zeitschriftenartikel (57)
- Buchkapitel (1)
- Beitrag zu einem Sammelband (1)
Referierte Publikation
- ja (59) (entfernen)
Schlagworte
- Phosphorus (4)
- Bottom ash (3)
- Fertilizer (3)
- Phosphorus fertilizer (3)
- Archaeometry (2)
- Biodeterioration (2)
- Biofilm (2)
- Biogenic weathering (2)
- Black fungi (2)
- Circular economy (2)
Organisationseinheit der BAM
- 4 Material und Umwelt (59) (entfernen)
Paper des Monats
- ja (3)
This study investigated the adaptation of the state-of-the-art test procedure for the determination of emissions of volatile organic compounds (VOC) from materials into indoor air to test for the radon exhalation from stony construction products. A complete robustness validation including all relevant parameters showed that the procedure can be well applied by testing institutes already holding available the required VOC testing infrastructure that solely needs to be complemented by calibrated commercial radon measurement instrumentation. When measurements of the radon exhalation from construction materials become mandatory by law, test capacity can easily be applied. This work can serve as a recommendation for the European standardisation that still is on hold in this point.
The reliable measurement of very volatile organic compounds (VVOC) in indoor air by use of thermal desorption gas chromatography (TD-GC) in order to include them into evaluation schemes for building products even nowadays is a great challenge. For capturing these small molecules with carbon numbers ranging from C 1 –C 6 , strong adsorbents are needed. In the present study, recovery rates of nine suitable adsorbents of the groups of porous polymers, graphitised carbon blacks (GCB) and carbon molecular sieves (CMS) are tested against a complex test gas standard containing 29 VVOC. By consideration of the recovery and the relative humidity (50% RH), combinations of the GCB Carbograph 5TD, the two CMS Carboxen 1003 and Carbosieve SII as well as the porous polymer Tenax® GR were identified to be potentially suitable for sampling the majority of the VVOC out of the gas mix. The results reveal a better performance of the adsorbents in combination than being used alone, particularly under humid sampling conditions. The recovery rates of the chosen compounds on each adsorbent should be in the range of 80–120%.
The growth rate of single bacterial cells is continuously disturbed by random fluctuations in biosynthesis rates and by deterministic cell-cycle events, such as division, genome duplication, and septum formation.
It is not understood whether, and how, bacteria reject these growth-rate disturbances. Here, we quantified growth and constitutive protein expression dynamics of single Bacillus subtilis cells as a function of cell-cycle progression. We found that, even though growth at the population level is exponential, close inspection of the cell cycle of thousands of single Bacillus subtilis cells reveals systematic deviations from exponential growth.
Newborn cells display varying growth rates that depend on their size. When they divide, growth-rate Variation has decreased, and growth rates have become birth size independent. Thus, cells indeed compensate for growth-rate disturbances and achieve growth-rate homeostasis. Protein synthesis and growth of single cells displayed correlated, biphasic dynamics from cell birth to division. During a first phase of variable duration, the absolute rates were approximately constant and cells behaved as sizers. In the second phase, rates increased, and growth behavior exhibited characteristics of a timer strategy. These findings demonstrate that, just like size homeostasis, growth-rate homeostasis is an inherent property of single cells that is achieved by cell-cycle-dependent rate adjustments of biosynthesis and growth.
The evolutionary success of insects is promoted by their association with beneficial microbes that enable the utilization of unusual diets. The synanthropic clothing moth Tineola bisselliella provides an intriguing example of this phenomenon. The caterpillars of this species have adapted to feed on keratin-rich diets such as feathers and wool, which cannot be digested by most other animals and are resistant to common digestive enzymes. Inspired by the hypothesis that this ability may be conferred by symbiotic microbes, we utilized a simple assay to detect keratinase activity and a method to screen gut bacteria for candidate enzymes, which were isolated from feather-fed larvae. The isolation of DNA from keratin-degrading bacterial strains followed by de novo genome sequencing resulted in the identification of a novel bacterial strain related to Bacillus sp. FDAARGOS_235. Genome Annotation identified 20 genes with keratinase domains. Proteomic analysis of the culture supernatant from this gut bacterium grown in non-nutrient buffer supplemented with feathers revealed several candidate enzymes potentially responsible for keratin degradation, including a thiol-disulfide oxidoreductase and multiple proteases. Our results suggest that the unusual diet of T. bisselliella larvae promotes their association with keratinolytic microorganisms and that the ability of larvae to feed on keratin can at least partially be attributed to bacteria that produce a cocktail of keratin-degrading enzymes.
What Does Ectoine Do to DNA? A Molecular-Scale Picture of Compatible Solute−Biopolymer Interactions
(2020)
Compatible solutes are accumulated in the cytoplasm of halophilic microorganisms. These molecules enable their survival in a high salinity environment. Ectoine is such a compatible solute. It is a zwitterionic molecule which strongly interacts with surrounding water molecules and changes the dynamics of the local hydration shell. Ectoine interacts with biomolecules such as lipids, proteins and DNA. The molecular interaction between ectoine and biomolecules in particular the interaction between ectoine and DNA is far from being understood.
In this paper we describe molecular aspects of the interaction between ectoine and double stranded DNA(dsDNA). Two 20 base pairs long dsDNA fragments were immobilized on a Gold surface via a thiol-tether. The interaction between the dsDNA monolayers with diluted and concentrated ectoine solutions was examined by means of X-ray photoelectron and polarization modulation infrared reflection absorption spectroscopies (PM IRRAS). Experimental results indicate that the ability of ectoine to bind water reduces the strength of hydrogen bonds formed to the ribose-phosphate backbone in the dsDNA. In diluted (0.1 M) ectoine solution, DNA interacts predominantly with water molecules. The sugar-phosphate backbone is involved in the formation of strong hydrogen bonds to water, which with elapsing time leads to a reorientation of the planes of nucleic acid bases. This reorientation destabilizes the hydrogen bonds strength between the bases and leads to a partial dehybridizaiton of the dsDNA. In concentrated ectoine solution (2.5 M), almost all water molecules interact with ectoine. Under this condition ectoine is able to interact directly with DNA. Density functional theory (DFT) calculations demonstrate that the direct interaction involves the nitrogen atoms in ectoine and phosphate groups in the DNA molecule. The results of the quantum chemical calculations Show that rearrangements in the ribose-phosphate backbone, caused by a direct interaction with ectoine, facilitates contacts between O atom in the phosphate group and H atoms in a nucleic acid base. In the PM IRRA spectra, an increase in the number of the IR absorption modes in the base pair frequency region proves that the hydrogen bonds between bases become weaker.
Thus, a sequence of reorientations caused by interaction with ectoine leads to a breakdown of hydrogen bonds between bases in the double helix.
The Brazilian sugarcane industry produced around 173 million tons (Mt) of bagasse in 2018. Bagasse is a by-product of juice extraction for ethanol and sugar production and is combusted in order to generate power, producing up to 10 Mt of ash per year. This ash contains various concentrations of plant nutrients, which allow the ash to be used as a crop fertilizer. However, the concentration and extractability of phosphorus (P), an essential plant nutrient, are low in bagasse ash. To increase the P content, we co-gasified and co-combusted bagasse with P-rich chicken manure. The resulting ash was thermochemically post-treated with alkali additives (Na2SO4 and K2SO4) to increase the availability of P to plants. We aimed to: (i) investigate the effect of thermochemical post-treatment of co-gasification residue and co-combustion ash on P availability to soybeans, (ii) explore the potential of chemical extraction methods (citric acid, neutral ammonium citrate, formic acid, and Mehlich-I) and diffusive gradients in thin films (DGT) to predict the availability of P to soybeans, and (iii) identify the responsible P-phases using X-ray diffraction . We evaluated P availability to soybeans growing in Brazilian Oxisol soil in two independent greenhouse pot experiments. The positive effect of thermochemical treatment on P availability from gasification residue was confirmed through the observation of increased P uptake and biomass in soybean plants. These findings were confirmed by chemical extraction methods and DGT. The gasification residue contained whitlockite as its main P-bearing phase. Thermochemical post-treatment converted whitlockite into highly soluble CaNaPO4. In contrast, co-combustion ash already contained highly soluble Ca(Na,K)PO4 as its main P-bearing phase, making thermochemical post-treatment unnecessary for increasing P availability. In conclusion, increased extractability and availability of P for soybeans were closely connected to the formation of calcium alkali phosphate. Our findings indicate that this combined methodology allows for the prediction of P-fertilization effects of ash.
Stress is a normal part of life for fungi, which can survive in environments considered inhospitable or hostile for other organisms. Due to the ability of fungi to respond to, survive in, and transform the environment, even under severe stresses, many researchers are exploring the mechanisms that enable fungi to adapt to stress. The International Symposium on Fungal Stress (ISFUS) brings together leading scientists from around the world who research fungal stress. This article discusses presentations given at the third ISFUS, held in Sao Jose dos Campos, Sao Paulo, Brazil in 2019, thereby summarizing the state-of-the-art knowledge on fungal stress, a field that includes microbiology, agriculture, ecology, biotechnology, medicine, and astrobiology.
Timber is constantly exposed to environmental influences under outdoor conditions which limits its Lifetime and usability. In order to counteract the damaging processes caused by insects, we have developed a novel and more environmentally friendly method to protect wood materials via covalent modification by organic insecticides. Starting with an important class of synthetic insecticides which are derived from the natural insecticide nicotine, various new carboxylic acid derivatives of imidacloprid were made accessible. These activated neonicotinoids were utilized for the chemical modification of wood hydroxy groups. In contrast to conventional wood preservation methods in which biocides are only physically bound to the surface for a limited time, the covalent fixation of the preservative guarantees a permanent effect against wood pests, demonstrated in standardized biological tests. Additionally, the environmental interaction caused by non-bound neonicotinoids is significantly reduced, since both, a smaller application rate is required and leaching of the active ingredient is prevented. By minimizing the pest infestation, the lifetime of the material increases while preserving the natural appearance of the material.
New antibacterial agents are urgently required to fight the emergence of antibiotic-resistant bacteria. We recently synthesized the first thioimidazolium ionene, which has antibacterial properties and can degrade in various media. This dual functionality is crucial in order to limit the environmental impact of these biocides. We have found that our polymer is stronger than benzalkonium chloride (BAC) against Pseudomonas aeruginosa and also readily degrades in the presence of base, while remaining stable in acidic environments. These results highlight a new emerging class of antibacterial degradable polymers.
The application of fracture mechanics to the determination of the fatigue behavior of weldments is discussed with the focus on classic fatigue, i.e., the overall fatigue life and the fatigue strength in terms of an S-N curve and the endurance limit. The following issues are addressed: specific features of short fatigue crack propagation, an adequate initial crack size, multiple crack propagation and its statistical treatment as well as welding residual stresses. As an example, an approach of the authors is applied to the determination of FAT classes for a butt weld with varying weld toe geometry.