4.12. Growth Inhibition Assay

Saccharomyces cerevisiae (ATCC 9763), Escherichia coli and Staphylococcus aureus were obtained from the Czech Collection of Microorganisms, Faculty of Science, Masaryk University, Brno, Czech Republic. For the determination of growth curves of experimental models selected, the LB medium (trypton, yeast extract, NaCl) was used. The cultures were first cultivated for 24 h, then diluted to 0.1 of the optical density (OD) at 600 nm and placed in a well for 24 h. Cultivated yeast (S. cerevisiae) and microorganisms (E. coli, S. aureus) were diluted using LB media to the OD of 0.1 before measurement. 250 µL of diluted yeast or microorganisms was pipetted into each well and 50 µL of the subsequent tested sample was added. As a control, the 300 µL of LB media was added to the separate well. The measurement was carried out on the Infinite 200 PRO multifunctional microplate reader (Tecan, Männedorf, Switzerland) at 600 nm for 18 h and 37 °C. The absorbance value was recorded every 30 min. Each sample was analysed using 5 independent repetitions. The results were expressed as a average value. After measuring the growth curves, the IC₅₀ was calculated by probit analysis using the QINSLAB information system.