This diploma thesis focuses on antibacterial effect of plant oils containing medium-chain fatty acids (MCFA). The minimum inhibitory concentration (MIC) of eight chosen plant oils was defined as the mode of the lowest concentrations that were able to reduce the bacterial growth of 13 pathogenic and 6 beneficial intestinal strains of bacteria by 80 %. Coconut (Cocos nucifera), palm, red palm and palm kernel (Elaeis guineensis), Cuphea (C. lanceolata and C. ignea), babassu (Attalea speciosa, syn. Orbignya speciosa), tucuma (Astrocaryum vulgare), and muru-muru (Astrocaryum murumuru) oils were selected. Their antibacterial activity was tested towards following bacteria: Bifidobacterium animalis, B. longum, Campylobacter jejuni, Clostridium perfringens, Enterococcus cecorum, Escherichia coli, Lactobacillus acidophilus, L. fermentum, Listeria monocytogenes, Salmonella enteritidis, S. infantis, S. typhimurium and Staphylococcus aureus. To identify the fatty acids composition of tested oils a gas chromatography was used. Consequently, the MIC of each oil towards all the bacteria was determined by a broth-microdilution test in 96-well microtitration plates. The essentiality of cleavage of selected oils by lipase was observed, in order to activate their antibacterial effect. None of the tested oils exhibited any potential to inhibit the growth of Gramnegative bacterial strains even after cleavage. Furthermore palm and palm red oil did not exhibit any antibacterial action towards any of the tested bacterial strains. The strongest antibacterial activity was observed in tucuma oil, that inhibited C. perfringens by MIC=0.14 mg/ml. Other oils inhibited the growth of C. perfringens in concentrations from 0.25 to 4.5 mg/ml. The growth of E. cecorum was inhibited by coconut, babassu, Cuphea, palm kernel, muru-muru and tucuma oil in MIC range between 1.12 - 4.5 mg/ml. The only compound active against L. monocytogenes was Cuphea oil (MIC 1.12 mg/ml). Oils that were able to inhibit the growth of S. aureus strain showed MIC from 0.56 to 2.25 mg/ml (coconut, babassu, Cuphea, palm kernel, muru-muru and tucuma oil). Undetected susceptibility of B. animalis, B. longum, L. acidophilus and L. fermentum bacterial strains to tested oils was evaluated as a positive effect. According to the foregoing statements, it can be concluded that the plant oils containing MCFA show antibacterial effect towards Grampositive strains of bacteria after their cleavage by lipase. No showed influence to beneficial intestinal microflora can be a big advantage.
| Identifer | oai:union.ndltd.org:nusl.cz/oai:invenio.nusl.cz:259850 |
| Date | January 2016 |
| Creators | Laloučková, Klára |
| Contributors | Skřivanová, Eva, Rondevaldová, Johana |
| Publisher | Česká zemědělská univerzita v Praze |
| Source Sets | Czech ETDs |
| Language | Czech |
| Detected Language | English |
| Type | info:eu-repo/semantics/masterThesis |
| Rights | info:eu-repo/semantics/restrictedAccess |
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