Taking into account different literature reports on microwave (MW) effects on living organisms, we thoroughly investigated the influence of constant 2.45 GHz MW irradiation on glucose uptake in yeast ...cells. A
Saccharomyces cerevisiae
suspension of 2.9 × 10
8
cells/ml was used in all experiments. A large specific absorption rate of 0.55 W/g of suspension is compensated by efficient external cooling of the reaction vessel, which established a strong non-equilibrium flow of energy through the solution and enabled a constant bulk temperature of 30 °C to within 1 °C during glucose uptake. Comparison of MW effects with control experiments revealed insignificant changes of glucose uptake during the initial stages of the experiment (up to the 10th min). Statistically “notable” differences during the next 20 min of the irradiation were detected corresponding to thermal overheating of 2 °C. Possible specific thermal MW effects may be related to local temperature increase and a large flow of energy throughout the system. The obtained effects show that environmental MW pollution (fortunately) is of too low intensity to provoke metabolic changes in living cells. At the same time, a longer exposure of cells to electromagnetic irradiation may have impacts on biochemical applications and production of valuable biotechnological products.
A comparative analysis of rhamnolipids from environmental isolates of
Pseudomonas aeruginosa
was undertaken to evaluate strain-specific rhamnolipid fingerprints obtained under different growth ...conditions. Environmental isolates of
P. aeruginosa
produced rhamnolipids on different types of substrates, including cheap and renewable sources like sunflower oil from deep fryers and sunflower oil mill effluent. Rhamnolipids were monitored by high-performance liquid chromatography–electrospray ionization interface mass spectrometry, which allowed fast and reliable identification and quantification of the congeners present. The highest concentration of total rhamnolipids of 3.33 g/l was obtained by the strain
P. aeruginosa
67, recovered from petroleum contaminated soil, and strains D1 (1.73 g/l) and D2 (1.70 g/l), recovered from natural microbial consortia originated from mazut-contaminated soil, grown on sunflower oil as a carbon source. Di- to mono-rhamnolipids ratios were in the range of 0.90–5.39 for different media composition and from 1.12 to 4.17 for different producing strains. Rhamnolipid profiles of purified mixtures of all tested strains are similar with chain length from C
8
–C
12
, pronounced abundance of Rha–C
10
–C
10
and Rha–Rha–C
10
–C
10
congeners, and a low content of 3-(3-hydroxyalkanoyloxy)-alkanoic acids. Concentrations of major congeners of RLs were found to slightly vary, depending on strain and growth conditions, while variations in minor congeners were more pronounced. Statistically significant increase of critical micelle concentration values was observed with lowering the ratio of total mono- to di-rhamnolipids ratio indicating that mono-rhamnolipids start to form micelles at lower concentration than di-rhamnolipids.
Pharmaceutical compounds have been detected frequently in surface and ground water. Advanced Oxidation Processes (AOPs) were reported as very efficient for removal of various organic compounds. ...Nevertheless, due to incomplete degradation, toxic intermediates can induce more severe effects than the parent compound. Therefore, toxicity studies are necessary for the evaluation of possible uses of AOPs.
In this study the effectiveness and capacity for environmental application of three different AOPs were estimated. They were applied and evaluated for removal of ibuprofen from water solutions. Therefore, two treatments were performed in a non-thermal plasma reactor with dielectric barrier discharge with and without a homogenous catalyst (Fe2+). The third treatment was the Fenton reaction.
The degradation rate of ibuprofen was measured by HPLC-DAD and the main degradation products were identified using LC–MS TOF. Twelve degradation products were identified, and there were differences according to the various treatments applied. Toxicity effects were determined with two bioassays: Vibrio fischeri and Artemia salina. The efficiency of AOPs was demonstrated for all treatments, where after 15min degradation percentage was over 80% accompanied by opening of the aromatic ring. In the treatment with homogenous catalyst degradation reached 99%. V. fischeri toxicity test has shown greater sensitivity to ibuprofen solution after the Fenton treatment in comparison to A. salina.
•Twelve ibuprofen degradation products were identified in total.•The degradation percentage differed between treatments (DBD/Fe2+ was 99%).•In DBD/Fe2+ only aliphatic degradation products were identified.•V. fischeri was sensitive to ibuprofen solution after the Fenton treatment.•A. salina showed no toxic effect when exposed to all post treatment solutions.
•PAHs degradation from diesel fuel aromatic fraction was investigated.•Novel method was applied for the visualization degraded compounds in the GC × GC-TOF MS chromatograms.•Oerskovia sp. CHP-ZH25 ...has successfully degraded different PAHs from diesel fuel aromatic fraction.
Polycyclic aromatic hydrocarbons (PAHs) from petroleum and fossil fuels are one of the most dominant pollutants in the environment. Since aromatic fraction from petroleum diesel fuel is mainly composed of PAHs, it is important to discover new microorganisms that can biodegrade these compounds. This article describes the biodegradation of the aromatic fraction separated from petroleum diesel fuel using the strain Oerskovia sp. CHP-ZH25 isolated from petroleum oil-contaminated soil. The biodegradation was monitored by gravimetry and GC × GC-TOF MS. An innovative method was applied to visualize degraded compounds in the data provided by a GC × GC-TOF MS. It was shown that Oerskovia sp. CHP-ZH25 degraded 77.4% based on gravimetric analysis within 30 days. Average rate of degradation was 14.4 mg/L/day, 10.5 mg/l/day and 4.0 mg/l/day from 0 to 10 day, 10–20 and 20–30 day, respectively. The order of PAH degradation based on decrease in peak volume after 30 days of incubation was as follows: dibenzothiophene derivatives > benzobthiophene derivatives > naphthalene derivatives > acenaphthene derivatives > acenaphthylene/biphenyl derivatives > fluorene derivatives > phenanthrene/anthracene derivatives. Here we demonstrated that Oerskovia sp. CHP-ZH25 could potentially be a suitable candidate for use in bioremediation of environments polluted with different PAHs.
One of the main global focuses of mankind today is the required switch to new energy sources. Generating energy from waste is one of the potential solutions that can be achieved using microbial fuel ...cells (MFCs). Microorganisms, thanks to their ability to degrade organic substrates in contaminated environments, could contribute to solving our pollution challenge. The aim of this study was to investigate the potential of sediment with its natural microbiota from the River Danube to optimize electricity generation using MFCs. 16S rRNA gene analysis identified the main bacterial genera in the river sediment, Clostridium, Bacillus and Tepidibacter, which were isolated and cultured in the laboratory. Addition of these cultured microorganisms to the MFC resulted in current density of 192 mA/m3, while the power density was about 8.80 mW/m3. Our study confirms proper selection and enrichment of the microbial community can optimize the amount of current obtainable from river sediment by MFCs.
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•Sampling sediment from the Danube River.•Characterization of microbial communities of composite sediment.•Construction and electrical characterization of 4 different MFCs.•Investigation of impact of microbial communities on MFCs power production.•The high power density (10.6 mW/m3) was obtained.
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•Polysaccharides (PS) levan and pullulan were hydrophobized by cholesterol.•New C60-PS non-covalent hybrid NPs were synthesized and studied by DLS and SEM.•The size of C60-PS NPs in ...water was reduced compared to starting PS NPs.•DPPH radical scavenging and β-carotene bleaching abilities of NPs were studied.•The antioxidant potency increases with the growing hydrophobicity.
An efficient encapsulation of the fullerene into two hydrophobized and one native polysaccharide provided water soluble supramolecular hybrids. After covalent modification of polysaccharides by cholesterol, noncovalent hybrids were prepared by a three-step procedure, including mixing of individual aqueous solutions of hydrophobized, as well as native sugar with solution of the fullerene in pyridine, dialysis and lyophilization. Although the degree of the fullerene incorporation into hydrophobized substrates, cholesterol-levan and cholesterol-pullulan, was lower in comparison to the native polysaccharide levan, hydrophobization provided nanoparticles with improved properties. The particle size distribution, studied by dynamic light scattering and scanning electron microscopy revealed formation of moderately polydisperse aggregates, with the diameter contraction in comparison to the corresponding free polysaccharide, especially in the case of hydrophobized substrates. The morphological examination, done by scanning electron microscopy indicated the self-organization of the fullerene-native polysaccharide to round individual structures, while fullerene-hydrophobized polysaccharide hybrids tend to form networks. The antioxidant activity of the synthesized polysaccharide-C60 noncovalent hybrids versus starting polysaccharides was investigated by the DPPH radical scavenging and the β-carotene-linoleic acid bleaching methods. In all three complexes, the radical scavenging ability of the fullerene remained preserved, and a positive effect of levan hydrophobization was observed.
Ongoing demand in sustainable and biocompatible drug dosage forms is reflected in the search for novel pharmaceutical excipients with equal properties. A group of microbial exopolysaccharides offers ...a variety of biopolymers with many alleged uses and effects. This study aims to assess applicative properties of levan obtained from Bacillus licheniformis NS032, focusing on its potential co-stabilizing and drug release-controlling functions in pertaining emulsion systems. Despite its high molecular weight and partial existence in globular nanometric structures (180-190 nm), levan was successfully incorporated into both tested colloidal systems: those stabilized with synthetic/anionic or natural-origin/non-ionic emulsifiers. In the tested levan concentrations range (0.2-3.0% w/w) the monitored flow and thermal parameters failed to show linear concentration dependence, which prompted us to revisit certain colloidal fundamentals of this biopolymer. Being a part of the external phase of the investigated emulsion systems, levan contributed to formation of a matrix-like environment, offering additional stabilization of the microstructure and rheology modifying properties (hysteresis loop elevation as high as 4167±98 to 20792±3166 Pa•s−1), especially in case of the samples where lamellar liquid crystalline formation occurred. Apart from its good water solubility and considerable conformational flexibility, the investigated homofructan easily saturated the external phase of the samples stabilized with a conventional anionic emulsifier, leading to similar properties of 0.2% and 3.0% levan-containing samples. After closer consideration of thermal and release behavior, this was considered as a favorable property for a novel excipient, offering tailored formulation characteristics even with lower levan concentrations, consequently not compromising the potential cost of the final drug dosage form.
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Iron and sulfur oxidizing chemolithoautotrophic acidophilic bacteria, such as Acidithiobacillus species, hold the dominant role in mine environments characterized by low pH values and high ...concentrations of reduced sulfur and iron compounds, such as ores, rocks and acid drainage waters from mines. On the other hand, heterotrophic microorganisms, especially their biofilms, from these specific niches are receiving increased attention, but their potential eco-physiological roles have not been fully understood. Biofilms are considered a threat to human health, but biofilms also have beneficial properties as they are deployed in waste recycling and bioremediation systems. We have analyzed interactions of the metal tolerant heterotrophic microorganisms in biofilms with iron oxidizing autotrophic bacteria both from the sulphidic mine environment (copper mine Bor, Serbia). High tolerance to Cu2+, Cd2+ and Cr6+ and the presence of genetic determinants for the respective metal tolerance and biofilm-forming ability was shown for indigenous heterotrophic bacteria that included strains of Staphylococcus and Rhodococcus. Two well characterized bacteria- Pseudomonas aeruginosa PAO1 (known biofilm former) and Cupriavidus metallidurans CH34 (known metal resistant representative) were also included in the study. The interaction and survivability of autotrophic iron oxidizing Acidithiobacillus bacteria and biofilms of heterotrophic bacteria during co-cultivation was revealed. Finally, the effect of heterotrophic biofilms on bioleaching process with indigenous iron oxidizing Acidithiobacillus species was shown not to be inhibitory under in vitro conditions.
•Heterotrophic bacteria from the mining area showed high tolerance to heavy metals.•Pseudomonas aeruginosa PAO1 tolerated elevated concentrations Cd2+, Cr6+ and Cu2+.•Biofilms of heterotrophs showed higher tolerance to mixed metals.•Biofilms were resistant to low pH and did not affect growth of Acidithiobacillus sp.•Biofilms did not affect bioleaching process of Acidithiobacillus sp.
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