diplomsko delo
Anamarie Žalik (Author), Marko Kreft (Reviewer), Sonja Smole Možina (Mentor)

Abstract

Za preprečevanje kvara hrane in obvladovanje povzročiteljev okužb in zastrupitev s hrano so še vedno pogosto v uporabi kemijski konzervansi. Med potrošniki so nezaželeni zaradi potencialno negativnih učinkov, vključno z nevarnostmi za zdravje ljudi zaradi kemijskih ostankov v živilskih izdelkih ter pridobivanjem odpornosti mikroorganizmov na uporabljene kemijske učinkovine. S tem se je povečala potreba po iskanju učinkovitih naravnih protimikrobnih sredstev. V diplomskem delu smo preiskovali protimikrobno učinkovitost izvlečkov navadne koprive (Urtica dioica) in dveh vrst mrtve koprive (Lamium orvala in Lamium galeobdolon) na sevih bakterij Listeria monocytogenes, Staphylococcus aureus, Escherichia coli in Pseudomonas fragi, izoliranih iz hrane. Najprej smo iz posušenih rastlin pripravili etanolne izvlečke in z mikrodilucijsko metodo testirali njihovo učinkovanje, kar smo ovrednotili kot minimalno inhibitorno koncentracijo (MIK) in minimalno baktericidno koncentracijo (MBK). Izvlečki so pokazali protimikrobno delovanje pri vseh testiranih bakterijah, pri tem je bil izvleček navadne koprive (U. dioica) nekoliko učinkovitejši kot izvlečka mrtve koprive (L. orvala in L. galeobdolon). Rezultati so pokazali, da je ekstrakt U. dioica primerljivo oz. bolje deloval na gramnegativne bakterije kot na grampozitivne, saj je najbolje inhibiral rast gramnegativne bakterije P. fragi. Protimikrobno učinkovanje izvlečkov mrtve koprive L. orvala in L. galeobdolon je bilo primerljivo, razlika se je pokazala le pri bakteriji P. fragi, ki jo je bolje inhibiral izvleček L. galeobdolon.

Keywords

protimikrobne snovi;rastlinski izvlečki;navadna kopriva;Urtica dioica;mrtva kopriva;Lamium sp.;protimikrobna aktivnost;patogene bakterije;metoda mikrodilucije;minimalna inhibitorna koncentracija;minimalna baktericidna koncentracija;

Data

Language: Slovenian
Year of publishing:
Typology: 2.11 - Undergraduate Thesis
Organization: UL BF - Biotechnical Faculty
Publisher: [A. Žalik]
UDC: 579.24/.26:547.9
COBISS: 5097592 Link will open in a new window
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Downloads: 195
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Other data

Secondary language: English
Secondary title: Antimicrobial activity of ethanolic extracts of stinging (Urtica dioica) and dead nettle (Lamium sp.)
Secondary abstract: Chemical preservatives are still commonly used to prevent food spoilage and control infectious agents and food poisoning. Among consumers they are undesirable because of the potentially negative effects, including the dangers to human health of chemical residues in food products and the acquisition of resistance of microorganisms to the chemical substances used. This has increased the need to find effective natural antimicrobials. In the thesis we investigated the antimicrobial efficacy of extracts of nettle (Urtica dioica) and two dead nettle species (Lamium orvala and Lamium galeobdolon) on the food strains of Listeria monocytogenes, Staphylococcus aureus, Escherichia coli and Pseudomonas fragi. First, ethanol extracts were prepared from the dried plants and their effect was tested by microdilution method, which was evaluated as minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The extracts showed antimicrobial activity against all bacteria tested, while the extract of stinging nettle (U. dioica) was slightly more effective than the extract of dead nettle (L. orvala and L. galeobdolon). Surprisingly, the results showed that U. dioica extract had a comparable or better effect on gram-negative bacteria than on gram-positive ones, as it best inhibited the growth of gram-negative bacteria P. fragi. The antimicrobial effect of the dead nettle extracts of L. orvala and L. galeobdolon was comparable, with the difference only in P. fragi, which was better inhibited by the L. galeobdolon extract.
Secondary keywords: antimicrobials;plant extracts;stinging nettle;Urtica dioica;dead nettle;Lamium sp.;antimicrobial activity;pathogens;microdilution method;minimal inhibitory concentration;minimal bactericidal concentration;
Type (COBISS): Bachelor thesis/paper
Study programme: 0
Embargo end date (OpenAIRE): 1970-01-01
Thesis comment: Univ. v Ljubljani, Biotehniška fak., Oddelek za živilstvo
Pages: VIII, 25 f.
ID: 11223616