In the thesis we wanted to determine the antimicrobial efficacy of plant extracts from Ecballium elaterium and Cucurbita pepo against selected bacterial and fungal species. We evaluated the growth inhibition of the Gram positive bacterium (Staphylococcus aureus), the Gram negative bacterium (Escherichia coli) and two mycotoxigenic molds (Aspergillus flavus and A. niger). We tested the ethanol extract of E. elaterium fruit and ethanol extract of C. pepo dried and ground pumpkin oil cake using microdilution method on a microtiter plate. The minimum inhibitory concentration (MIC) of both extracts was determined. Results showed that the ethanol extract of E. elaterium fruit expressed better growth inhibition of both bacteria and molds compared to pumpkin oil cake extract, which required higher concentrations. The ethanol extract of E. elaterium inhibited a Gram positive S. aureus with minimal inhibitory concentration 1,5–1,75 mg/ml and a Gram negative E. coli with MIC more than 3,5 mg/ml. MIC of the same extract on micotoxigenic mold A. niger was 37,5–75 mg/ml and 4,6–9,4 mg/ml for A. flavus. In the experiment the MIC of the ground and dried pumpkin oil cake ethanol extract was not determined precisely, due to the difficulty of preparing concentration of the extract higher than 150 mg/ml. The research showed that higher concentrations of both extracts are required for growth inhibition of Gram negative bacteria as well as for molds.
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