| Abstract [eng] |
Microalgae and bacteria have coexisted since the earliest stages of evolution. By optimising co-culture growth conditions, it is possible to increase the yield of desired compounds or reduce the use of synthetic compounds in agriculture and industry. The aim of this master‘s thesis is to evaluate the effect of the growth medium and pulsed e-lectric field on the functional properties of a mixed culture of Chlorella vulgaris and Serratia sp. AR11. The objectives of the thesis: to investigate the effect of growth medium on the interaction between C .vulgaris and Serratia sp. AR11 by assessing chlorophyll a and dry biomass concentra-tions of C. vulgaris; to investigate the response of C. vulgaris and Serratia sp. AR11 co-culture to pulsed electric field (PEF) treatment by evaluating phosphate solubilisation and nitrogen fixation indices of Serratia sp. AR11; to investigate the response of C. vulgaris and Serratia sp. AR11 co-culture to plasma-activated water (PAW) by evaluating phosphate solubilisation and nitrogen fixation indices. The effect of growth medium was investigated by cultivating pure C. vulgaris culture and its co-culture with Serratia sp. AR11 in three different media: BG-11, BG-11 supplemented with acetic acid, and TAP, assesssing changes in chlorophyll a and dry biomass concentrations. The effects of PEF and PAW on microalgae-bacteria interactions were evaluated based on the phospha-te solubilisation index (PSI) and qualitative nitrogen fixation analysis. The research was con-ducted at the Center for Physical Sciences and Technology, Bioelectrics laboratory, in 2025-2026. The growth medium had a significant effect on microorganisms interactions: BG-11 and BG-11 supplemented with acetic acid promoted increases in C. vulgaris chlorophyll a (2,25 and 1,75 fold, respectively) and dry biomass (1,78 and 3,18 fold, respectively) concentrations in co-culture with Serratia sp. AR11 compared to pure culture, whereas in TAP medium, chlorophyll a and biomass concentrations in C. vulgaris monoculture were 1,71 and 1,42 fold higher, respectively, than in co-culture. In mixed culture with C. vulgaris, following PEF treatment, the PSI of Serratia sp. AR11 increased statistically significantly by 1,3 fold after 24 h of incubation, while nitrogen fixation capacity was retained. The effect of PAW on phosphate solubilisation capacity depended on its age and cultivation duration – a significant positive effect was observed on days 1 and 2 of cultivation using 168 h old PAW, while nitrogen fixation capacity was retained. |
