Waste rapeseed oil is a useful substrate for polyhydroxyalkanoates (PHA) production employing Cupriavidus necator H16. In fed-batch mode, we obtained biomass and PHA yields of 138 and 105 g l -1 , respectively. Yield coefficient and volumetric productivity were 0.83 g PHA per g oil and 1.46 g l -1 h -1 , respectively. Propanol at 1% (v/v) enhanced both PHA and biomass formation significantly and, furthermore, resulted in incorporation of 3-hydroxyvalerate units into PHA structure. Thus, propanol can be used as an effective precursor of 3-hydroxyvalarete for production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) copolymer. During the fed-batch cultivation, propanol concentration was maintained at 1% which resulted in 8% content of 3-hydroxyvalerate in copolymer.

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Summary: Biodegradable thermosensitive triblock copolymers based on poly(ethylene glycol) and poly(lactic‐co‐glycolic acid) (PLGA‐PEG‐PLGA) prepared via ring opening polymerization were modified by itaconic anhydride (ITA), which gives copolymer both reactive double bonds and functional carboxylic acid groups essential for the reaction with biological active material. Functionalization conditions comprising ITA purification, temperature, time and presence of solvent were optimized with the respect to amount of end‐capped ITA. Maximum of 76.6 mol. % of bonded ITA were reached via “one pot” reaction in a bulk at 110 °C after 1.5 h. ITA functionalization thermally stabilized the original copolymer by increasing the initial degradation temperature Td from 284 °C to 294 °C and changing the negative glass transition temperature (Tg = ‐1.8 °C) to positive one up to 2.4 °C. The novel functionalized macromonomer can be cross‐linked either chemically or physically in order to produce new functionalized hydrogel network applicable as biomedical material in tissue engineering.

Poly(3-hydroxybutyrate) (PHB) is a polyester belonging to the family of polyhydroxyalkanoates, which accumulate in a wide variety of bacterial strains. PHB appears to be a biodegradable alternative to traditional petrochemical polymers such as polypropylene and polyethylene. In this work, we tested direct conversion of cheap waste cheese whey into PHB employing the bacterial strain Bacillus megaterium CCM 2037. Optimization of medium composition improved PHB yields about 50 fold (biomass and PHB yields 2.82 and 1.05 g l −1 , respectively) as compared to none-optimized whey. Furthermore, PHB yields were improved by about 40% by introducing 1% ethanol into the medium at the beginning of the stationary phase of growth (biomass 2.87 g l −1 , PHB 1.48 g l −1 ). According to the results of experiments carried out in Erlenmeyer flasks, B. megaterium CCM 2037 can be considered a candidate for direct PHB production from waste cheese whey. Nevertheless, experiments in laboratory-scale and semi-productive fermentors are needed to test performance under high cell density cultivation.

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This work is focused on the study of the effect of cholesterol on the properties of vesicular membranes of ionic amphiphilic pairs at different temperatures. The hexadecyltrimethylammonium-dodecyl sulfate ionic amphiphilic pair system with the addition of 10 mol % dioctadecyldimethylammonium chloride was chosen for a detailed study of vesicle properties. A large range of cholesterol concentrations (0–73 mol %) in the temperature range 10–80 °C was studied. Under these conditions, the size distribution, the membrane fluidity, and the surface layer were monitored together with the change in the mobility of water in the surface layer. Obtained quantities were correlated with each other and combined into appropriate graphs. It was found that in stable systems that meet the condition of unimodal size distribution with a PDI value lower than 0.3, temperature has virtually no effect on the size of vesicular systems. On the contrary, when studying the hydration and fluidity of the membrane, significant changes in these parameters were found, which, however, do not affect the short-term stability of these vesicular systems. The presented results thus indicate the possibility of adjusting the composition of the vesicular system in terms of fluidity and membrane hydration while maintaining short-term stability and size distribution.

Exposition of Cupriavidus necator to ethanol or hydrogen peroxide at the beginning of the stationary phase increases poly(3-hydroxybutyrate) (PHB) yields about 30%. Hydrogen peroxide enhances activity of pentose phosphate pathway that probably consequently increases intracellular ratio NADPH/NADP(+). This effect leads to stimulation of the flux of acetyl-CoA into PHB biosynthetic pathway and to an increase of enzymatic activities of β-ketothiolase and acetoacetyl-CoA reductase while activity of PHB synthase remains uninfluenced. During ethanol metabolisation, in which alcohol dehydrogenase is involved, acetyl-CoA and reduced coenzymes NAD(P)H are formed. These metabolites could again slightly inhibit TCA cycle while flux of acetyl-CoA into PHB biosynthetic pathway is likely to be supported. As a consequence of TCA cycle inhibition also less free CoA is formed. Similarly with hydrogen peroxide, activities of β-ketothiolase and acetoacetyl-CoA reductase are increased which results in over-production of PHB. Molecular weight of PHB produced under stress conditions was significantly higher as compared to control cultivation. Particular molecular weight values were dependent on stress factor concentrations. This could indicate some interconnection among activities of β-ketothiolase, acetoacetyl-CoA reductase and PHB molecular weight control in vivo.

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