This work aims at investigating the influence of the initial concentrations of carbon (glucose) and organic nitrogen (yeast extract) sources on Streptomyces rimosus ATCC10970 secondary metabolism in the stirred tank bioreactors. Additionally, glucose utilisation, biomass formation, pH, redox potential and dissolved oxygen levels, and the morphological development of S. rimosus pseudomycelium were studied. Eighteen secondary metabolites were detected by mass spectrometry and identified with the use of the authentic standard, or putatively with the use of literature and database of secondary metabolites. Varied initial yeast extract concentration acted much stronger on the formation of secondary metabolites than glucose did. For example, oxytetracycline was not biosynthesised at high yeast extract concentration while the formation of three other metabolites was enhanced under these conditions. In the case of glucose its increasing initial concentration led to higher secondary metabolite levels with the exception of an unnamed angucycline. High initial yeast extract concentration also drastically changed S. rimosus pseudomycelial morphology from the pelleted to the dispersed one. Ultimately, the cultivation media with the varied initial levels of carbon and nitrogen sources were proved to have the marked effect on S. rimosus secondary metabolism and to be the simplest way to either induce or block the formation of the selected secondary metabolites.

The demand of energy and the search for alternative energy sources are the reason why scientists are interested in starch hydrolysis. The aim of the work was to experimental study of the hydrolysis of starch by α–amylase from porcine pancreas with α–amylase deactivation. Based on the experiments data, the parameters of starch hydrolysis by α– amylase with deactivation of enzyme was estimated. A mathematical model of temperature impact on the activity of α–amylase from porcine pancreas was used. It has been estimated that the activation energy E_a and the deactivation energy E_d were equal to 66 ± 4 kJ/mol and 161 ± 12 kJ/mol, respectively. Additionally, specific constant of starch hydrolysis k ₀ and specific constant of α–amylase deactivation k _d0 were calculated. The optimum temperature T_opt equal to 318 ± 0.5 K was obtained from mathematical model. The obtained values of E_a, E_d, k ₀ and k _d0 parameters were used to the model starch hydrolysis by α–amylase from porcine pancreas at 310 K and 333 K.

The article presents a novel solution based on dairy wastewater sorption on a biochar substrate obtained through thermal decomposition of Chlorella sp. algae biomass. The algal biomass obtained in the culture medium containing wastewater from dairy production was separated from the culture medium through sedimentation and centrifugation and then freeze-dried. After freeze-drying, the dry biomass was pyrolysed at 600 °C in a CO ₂ atmosphere.The EDS analysis showed that the oxygen-tocarbon (O/C) and nitrogen-to-carbon (N/C) ratios in the obtained material averaged 0.24 and 0.54 respectively. The arrangement and structure of the obtained biochar was evaluated using Raman spectroscopy. The observed spectra revealed the presence of D bands located at 1346–1354 cm ^-1 and corresponding to disordered carbon structures, as well as G bands located at 1585–1594 cm ^-1 and corresponding to tensile vibrations. The D/G intensity ratio was determined at 0.28. The next phase of the research involved sorption of dairy wastewater from cleaning processes containing 1 g of the obtained biochar using solid phase extraction. The study results confirmed high sorption efficiency of the obtained algal biochar. Turbidity was reduced by 93%, suspension by 88%, sulphates by 61%, chlorides by 80%, and organic carbon by 17%. The research confirmed the possibility of using wastewater from dairy production as a natural culture medium for Chlorella sp. algae cultivation to manufacture valuable biochar, which could be used as a sorption bed in the treatment of dairy wastewater from cleaning processes.

The paper focused on the co-production of high-value-added product thermostable C-phycocyanin (C-PC) and biomass, further utilized in pyrolysis. The photobiosynthesis of CPC was carried out by the thermophilic cyanobacteria Synechococcus PCC6715 cultivated in the helical and flat panel photobioreactors (PBR). Despite the application of different inorganic carbon sources, both PBRs were characterized by the same growth efficiency and similar C-PC concentration in biomass. To release the intracellular C-PC the biomass was concentrated and disintegrated by the freeze-thaw method. The crude C-PC was then further purified by foam fractionation (FF), aqueous two-phase extraction (ATPE), membrane techniques (UF) and fast protein liquid chromatography (FPLC). Each of the tested methods can be used separately; however, from a practical and economic point of view, a three-stage purification system (FF, FPLC and UF) was proposed. The purity ratio of the final C-PC was about 3.9, which allows it to be classified as a reactive grade. To improve the profitability of 3G biorefinery, the solid biomass residue was used as a substrate to pyrolysis process, which leads to production of additional chemicals in the form of oils, gas (containing e.g. H ₂) and biochar.

Plastics have become indispensable in everyday life due to their properties. For this reason, the accumulation of polymer waste in the natural environment is becoming a serious global problem. The aim of the research was to isolate microorganisms capable of biodegrading plastics. The studies focused on the biodegradation of low-density polyethylene as the most common polymer. Seven and five bacterial strains were isolated from the landfill and compost, respectively. The morphological and biochemical characteristics of the isolates were determined. These isolates were able to survive in an environment where the only carbon source was LDPE, but no increase in biomass was obtained. However, analysis of the spectra obtained by the ATR-FTIR method showed the formation of chemical changes on the polymer surface. Bacterial biofilm formation was visualized by scanning electron microscopy. The toxicity of plastic biodegradation products in a liquid environment was tested and their safety for plants was confirmed. However, these biodegradation products have acute lethal toxicity for the Daphnia magna.
LDPE films were pre-treated with H ₂O ₂, HNO ₃, or heat. The biodegradation of HNO ₃-treated LDPE by isolated bacteria was the most significant. The weight loss was approximately 8%, and 6%, for landfill and compost-isolated bacterial strains, respectively.