Display omitted
•Physical and chemical parameters of commercial fountain pen inks were measured.•Ink consumption (the amount laid down on paper) was quantitatively measured.•Complex statistics was ...conducted to identify correlations between ink properties and behaviour.•A New Ink Consumption Theory was formulated, intended to be useful for all users.
Handwriting with a modern fountain pen is an unique experience in present time, far beyond the pure necessity of making notes. The differences to ballpoint pens, rollerballs or pencils are in the tactual perception of the nib gliding over the paper surface and in the visual impression of a freshly drawn ink line with all the colour impressions and changing light reflections when a wet line dries and reveals either shading or sheen. This subjective impression of the wet line is commonly described as ink wetness and a lot is discussed and speculated about why one ink writes „wet“ and another „dry“. While such a subjective impression can not, the amount of ink put onto the paper can be measured quantitatively. To that end, a number of commercially available fountain pen inks were used to draw lines of a certain length and the amount of ink laid down on the paper was measured. These ink consumption data were correlated to the physical and chemical properties by a principal component analysis. The most significant outcome was the primary dependence of „ink wetness“ on surface tension, followed by viscosity and conductivity with unexpected and partly counter-intuitive correlations.
Cyanobacteria are a large group of prokaryotic microalgae that are able to grow photo-autotrophically by utilizing sunlight and by assimilating carbon dioxide to build new biomass. One of the most ...interesting among many cyanobacteria cell components is the storage biopolymer polyhydroxybutyrate (PHB), a member of the group of polyhydroxyalkanoates (PHA). Cyanobacteria occur in almost all habitats, ranging from freshwater to saltwater, freely drifting or adhered to solid surfaces or growing in the porewater of soil, they appear in meltwater of glaciers as well as in hot springs and can handle even high salinities and nutrient imbalances. The broad range of habitat conditions makes them interesting for biotechnological production in facilities located in such climate zones with the expectation of using the best adapted organisms in low-tech bioreactors instead of using "universal" strains, which require high technical effort to adapt the production conditions to the organism's need. These were the prerequisites for why and how we searched for locally adapted cyanobacteria in different habitats. Our manuscript provides insight to the sites we sampled, how we isolated and enriched, identified (morphology, 16S rDNA), tested (growth, PHB accumulation) and purified (physical and biochemical purification methods) promising PHB-producing cyanobacteria that can be used as robust production strains. Finally, we provide a guideline about how we managed to find potential production strains and prepared others for basic metabolism studies.
Sample preparation protocols for conventional high voltage transmission electron microscopy (TEM) heavily rely on the usage of staining agents containing various heavy metals, most commonly uranyl ...acetate and lead citrate. However high toxicity, rising legal regulations, and problematic waste disposal of uranyl acetate have increased calls for the reduction or even complete replacement of this staining agent. One of the strategies for uranyless imaging is the employment of low-voltage transmission electron microscopy. To investigate the influence of different imaging and staining strategies on the final image of cyanobacterial cells, samples stained by uranyl acetate with lead citrate, as well as unstained samples, were observed using TEM and accelerating voltages of 200 kV or 25 kV. Moreover, to examine the possibilities of reducing chromatic aberration, which often causes issues when imaging using electrons of lower energies, samples were also imaged using a scanning transmission electron microscopy at 15 kV accelerating voltages. The results of this study demonstrate that low-voltage electron microscopy offers great potential for uranyless electron microscopy.
Poly(3-hydroxybutyrate) (PHB) is a biobased and biodegradable polymer with properties comparable to polypropylene and therefore has the potential to replace conventional plastics. PHB is ...intracellularly accumulated by prokaryotic organisms. For the cells PHB functions manly as carbon and energy source, but all possible functions of PHB are still not known. Synechocystis (cyanobacteria) accumulates PHB using light as energy and CO2 as carbon source. The main trigger for PHB accumulation in cyanobacteria is nitrogen and phosphorous depletion with simultaneous surplus of carbon and energy. For the above reasons, obtaining knowledge about external factors influencing PHB accumulation is of highest interest. This study compares the effect of continuous light exposure and day/night (16/8 h) cycles on selected physiology parameters of three Synechocystis strains. We show that continuous illumination at moderate light intensities leads to an increased PHB accumulation in Synechocystis salina CCALA 192 (max. 14.2% CDW – cell dry weight) compared to day/night cycles (3.7% CDW). In addition to PHB content, glycogen and cell size increased, while cell density and cell viability decreased. The results offer new approaches for further studies to gain deeper insights into the role of PHB in cyanobacteria to obtain bioplastics in a more sustainable and environmentally friendly way.
We set out to study what biodiversity is, and how it can be influenced by human activities. To carry out this research, we looked for two, relatively closed, natural small-island systems: one ...little-influenced by human settlement and another equivalent (same vegetation series aligned 200 m from the first) but heavily settled. In these two environments, two transects were created in 10 subecosystems, from the sea to the mainland. We sought similar subecosystems in both places. We selected a series of eight points along the same gradient in the two environments, with two additional nonoverlapping points, specific to “natural plus” or “natural minus”. We studied soil microorganisms and arthropods to have a large number of cases (OTUs) available, and also studied the microorganisms’ phylogenetic status. We also compared biodiversity with soil organic carbon (SOC) content, using two SOC measurement systems (with and without litter), to understand biodiversity starting from its potential source of food (SOC). The results surprised us: the biodiversity indices are higher in the anthropized environment; the level of biodiversity of these microorganisms (OTUs) is linked to the quantity of organic carbon measured in the first 30 cm of soil with two different methods, Carbon Still Yeomans (650 g of soil sample) and Skalar Primacs ATC-100-IC-E (1 g of soil sample). The following forced line at the origin explains 85% of the variance: Shannon–Wiener’s H = 1.42 • ln (TOC400); where ln = natural logarithm and TOC400 = organic carbon lost from a soil sample raised to 400 °C. The concept of biodiversity merges with that of survival: the more species there are, the better they are organized among themselves in the process of food consumption (SOC utilization), and the better they will be able to transform the environment to survive and evolve with it. We wanted to identify the differences in soil biodiversity of natural and anthropogenic ecosystems, to offer evidence-providing tools to land managers to achieve more ecologically efficient managing practices.
Novel unexpected functions of PHA granules Obruca, Stanislav; Sedlacek, Petr; Slaninova, Eva ...
Applied microbiology and biotechnology,
06/2020, Letnik:
104, Številka:
11
Journal Article
Recenzirano
Polyhydroxyalkanoates (PHA), polyesters accumulated by numerous prokaryotes in the form of intracellular granules, have been for decades considered being predominantly storage molecules. However, ...numerous recent discoveries revealed and emphasized their complex biological role for microbial cells. Most of all, it was repeatedly reported and confirmed that the presence of PHA granules in prokaryotic cells enhances stress resistance and robustness of microbes against various environmental stress factors such as high or low temperature, freezing, oxidative, and osmotic pressure. It seems that protective mechanisms of PHA granules are associated with their extraordinary architecture and biophysical properties as well as with the complex and deeply interconnected nature of PHA metabolism. Therefore, this review aims at describing novel and unexpected properties of PHA granules with respect to their contribution to stress tolerance of various prokaryotes including common mesophilic heterotrophic bacteria, but also extremophiles or photo-autotrophic cyanobacteria.
Key points
•
PHA granules present in bacterial cells reveal unique properties and functions.
•
PHA enhances stress robustness of bacterial cells.
Display omitted
•Digestate supernatant was successfully used for the cultivation of S. salina.•The performance of P3HB synthesised by phototroph cultivated S. salina has been discussed.•P3HB ...accumulated in S. salina is a promising biodegradable thermoplastic.•The stability of P3HB in the molten state has to be increased.
The current commercial production of polyhydroxyalkanoates (PHA) is based on heterotrophic bacteria, using organic carbon sources from crops. To avoid the competition with food and feed production, cyanobacteria, metabolising PHA from carbon dioxide can be used. This research focuses on the investigation of the thermal and rheological properties of PHA polymers accumulated by Synechocystis salina, which had been cultivated in digestate supernatant and a mineral medium. The dried bacterial cells had a polymer content of 5.5-6.6%. The relevance of the derived PHA polymers for the common melt polymer processing was correlated with their molecular mass distribution as well as with their thermal and rheological properties. The determined thermal and rheological properties showed that PHA polymers accumulated by S. salina on digestate supernatant or mineral medium are comparable with the commercial available poly(3-hydroxybutyrate). However, the results showed that PHA polymers in general require modification before melt processing to increase their stability in the molten state.
Political, economic and ecological reasons have recently been leading to efforts to replace fossil hydrocarbons and their products in a sustainable way. In order to replace fossil-based polymers, ...photoautotrophically produced polyhydroxybutryrates (PHBs), which are intracellular carbon storage products of nutrient-deprived microorganisms, seem to be a promising, biobased and biodegradable alternative. Although laboratory and pilot scale experiments have already been performed, no economic evaluation has been carried out so far. Consequently, valid claims on PHB production costs and the influence of different parameters, such as intracellular PHB-content, choice of cultivation system or location, cannot be made. In this study potential demonstration plants, equipped with different photoautotrophic cultivation systems and located at two sites, were designed to identify key parameters for a successful economic realization and implementation. Material and energy balances were determined to reveal specific PHB production costs for four different scenarios. Raw material and operating supply costs, expenditures for plant construction and operation as well as product amounts were determined using literature data for specified results from laboratory and pilot scale experiments. The lowest calculated PHB production price (24 € kg−1) accomplished in a thin-layer-system plant located in Southern Europe with 60% PHB-content of the produced biomass is significantly higher than the current market price of heterotrophically produced PHB. The most important cost factors in all scenarios are cultivation and harvesting costs accounting for 62 to 72% of the total specific production costs, followed by maintenance costs with a cost share of 11 to 14%. Therefore, the choice of a suitable cultivation system is the key driving factor for an economic PHB-production due to the currently high investment costs for photosynthetic biomass production systems. Specific production costs for a Southern compared to a Central European location amount to almost half of the costs.
•Calculation of production costs of photoautotrophically produced polyhydroxybutyrates.•Quantification of different cost shares of the production costs.•Quantitative comparison of Central and Southern European locations.•Calculation of economic impact of intracellular polyhydroxbutyrates-content.
PDF
