Key Engineering Materials Vol. 933

Abstract: Methanotrophs display the ability to consume methane as a carbon source and produce a wide-range of high-value products, e.g. ectoine/hydroxyectoine, poly-b-hydroxybutyrate (PHB), single cell protein, extracellular polysaccharides and lipids. Usually methanotrophs show low specific substrate consumption rates, which restricts their application at pilot and industrial scale. Thus, in order to reduce the time and costs of the cultivation process, it is vital to accelerate the growth of applied organisms. Usually, methanotrophic bacteria cultivations are carried out using fully synthetic mineral mediums (nitrate mineral salts medium (NMS)) without the addition of any growth factors. Potentially, higher biomass growth and substrate uptake rates can be achieved by supplementing the growth medium with vitamins, amino acids etc. or by using more bioavailable substrates.The aim of our research was to study the influence of growth factors such as vitamins, and different nitrogen sources (yeast extract, yeast nitrogen base with/without amino acids and tryptone) on the growth of Methylomonas methanica, Methylomicrobium alcaliphilum and Methylosinus trishosporium.Experiments for studying the influence of growth factors were carried out in shake flasks by varying the medium compositions and analyzing the effects of said variations on the kinetics of the cultivation, e.g. specific biomass growth rate and biomass yield from substrate.Subsequent tests of the developed nutrient medium, which promotes higher biomass growth rates, were carried out in laboratory 5 L bioreactor Methylosinus trishosporium cultivations to study the main process parameters.From the statistical analysis of experimental data it was observed, that supplementation of the growth medium with yeast extract or tryptone, seems to promote the growth rate of methanotrophs, when methanol is used as the main substrate. Furthermore, specific growth rates observed during cultivations in mediums containing vitamins (including cobolamin) also seem to positively affect the biomass growth rate. Based on the results of lab-scale bioreactor cultivations, using the identified medium composition it was possible to achieve a maximal biomass specific growth rate of 0.15 L⸱h^‑1 and productivity of 0.16 g⸱L^-1⸱h^-1.

Abstract: A balance between forest growth and deforestation must be maintained to ensure sustainable wood production. Faster forest growth increases the economic benefit and to achieve faster forest growth it should be provided with nutrients from which one of the most important is nitrogen. In this study, nitrogen isotope ratio and elemental concentrations were determined in samples of pine needles, which were collected in plots where nitrogen-containing soil improver (arginine phosphate) was used, as well as in plots without additional nitrogen input. The aim of the study was to evaluate the effect of arginine-containing soil improvers on the nitrogen and other element content in pine needles harvested from selected plots. The obtained results indicate that arginine phosphate fertilizer was taken up by pine seedlings - an increase in nitrogen (0.05% for control samples and 0.7% for samples applied with a soil improver) and a decrease in nitrogen isotope ratio were observed.

Abstract: A modern, healthy diet relies on ever greater consumption of fruits, vegetables and other plant-based foods, with apples being some of the most affordable and readily available fruits that in most cases can be produced locally. With the higher interest of consumers in certified organic food products, methods for testing the food authenticity are becoming of key interest. For a food product to be labelled “organic”, it must be grown in certain conditions, without the use of pesticides, herbicides and synthetic fertilizers to elevate the yield. In this study the effect of different fertilizers on the nitrogen isotope ratios and amino acid composition in apples has been evaluated. Different parts of an apple were analyzed, and it was determined that only seeds contained enough nitrogen to give reliable results on δ¹⁵N_AIR values and total nitrogen content. The results of apple seed analysis with stable isotope ratio mass spectrometry (SIRMS) showed that in three out of four apple varieties, the heavier nitrogen isotope (¹⁵N) content was higher in nitrogen-fertilized apples than in non-fertilized ones. Our research did not find any statistically significant correlation between the nitrogen and carbon content in apple seeds and the fertilization regime. The relative amino acid content in apple seeds was determined by gas chromatography and it was found that there is a moderate correlation between the stable nitrogen isotope ratios in apple seeds and the relative content of alanine and tryptophan.

Abstract: The aim of this research was to evaluate the impact of fly and bottom wood ash on the content of the rare earth elements in the forest soil and blueberries (Vaccinium myrtillus L.). The samples of forest soil and blueberry seedlings (fine roots, stem, leaves, berries) were collected from the different forest areas which were fertilized with bottom and fly wood ash. Obtained results demonstrated that the fly wood ash dispersion area was a significant impact on the increment of rare earth elements in the forest soil and blueberry fine roots.