A kinetic model to describe lovastatin biosynthesis by Aspergillus terreus ATCC 20542 in a batch culture with the simultaneous use of lactose and glycerol as carbon sources was developed. In order to do this the kinetics of the process was first studied. Then, the model consisting of five ordinary differential equations to balance lactose, glycerol, organic nitrogen, lovastatin and biomass was proposed. A set of batch experiments with a varying lactose to glycerol ratio was used to finally establish the form of this model and find its parameters. The parameters were either directly determined from the experimental data (maximum biomass specific growth rate, yield coefficients) or identified with the use of the optimisation software. In the next step the model was verified with the use of the independent sets of data obtained from the bioreactor cultivations. In the end the parameters of the model were thoroughly discussed with regard to their biological sense. The fit of the model to the experimental data proved to be satisfactory and gave a new insight to develop various strategies of cultivation of A. terreus with the use of two substrates.

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 amount of solid organic waste is constantly growing. This is caused by the growth of industrial and agricultural capacities, and the inefficiency of existing waste processing technologies. Biotechnologies can provide effective environmentally friendly solutions for waste treatment. Therefore, the goal of our work was to compare the efficiency of strictly anaerobic fermentation of multi-component solid organic waste with hydrogen synthesis and waste treatment with pulsed air access in batch bioreactors.During fermentation, the following parameters were controlled: pH, redox potential (Eh), concentration of dissolved organics, and the content of H2, O2, and CO2 in the gas phase. The efficiency was evaluated via the process duration, calculation of the ratio of the initial and final weight of waste (Кd), and the yield of molecular hydrogen. Obtained results revealed high efficiency of organic waste degradation in both variants. The weight of waste 83-fold and 86-fold decreased, respectively. The time required for fermentation in strictly anaerobic conditions was 4 days, whereas 7 days were required for the mode with pulsed air access. The first variant provided a 2.8-fold higher hydrogen yield (54±4,1 L/kg of waste), and the second one provided a decrease in the concentration of dissolved organic compounds in the fermentation fluid. Fermentation is the effective approach for accelerated degradation of solid organic waste. Strictly anaerobic fermentation appeared to be useful in the need to accelerate the process. The mode with the pulsed air access can provide not only degradation of solid waste but also purification of the fermentation fluid.