20.500.12556/RUL-184346 Delovanje protimikrobnih učinkovin cinamaldehida, citronske kisline, kofeina, linalola in nizina na po Gramu pozitivne in negativne bakterije The antimicrobial activity of cinnamaldehyde, citric acid, caffeine, linalool, and nisin against Gram-positive and Gram-negative bacteria Protimikrobna odpornost bakterij predstavlja resen in naraščajoč problem v medicini ter živilski industriji, zato je razvoj alternativnih protimikrobnih strategij ključnega pomena. Namen magistrskega dela je bil ovrednotiti protimikrobno delovanje izbranih naravnih učinkovin (cinamaldehid, citronska kislina, kofein, linalol in nizin) na izbrane po Gramu pozitivne (Enterococcus faecalis, Listeria innocua, Staphylococcus aureus, Streptococcus parasanguinis) in po Gramu negativne bakterije (Enterobacter cloacae, Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica Typhimurium). Z metodo mikrodilucije v tekočem gojišču smo določili vrednosti minimalne inhibitorne (MIK) in minimalne baktericidne koncentracije (MBK) z reagentoma resazurin in BacTiter-Glo. Vpliv učinkovin na rast in metabolno aktivnost bakterij smo spremljali z merjenjem optične gostote, nato pa smo podatke ovrednotili z analizo rastnih krivulj bakterij s programoma QurvE in Excel. Rezultati so pokazali, da se učinkovitost preučevanih učinkovin razlikuje glede na vrsto bakterij. Cinamaldehid se je izkazal kot najbolj učinkovita protimikrobna učinkovina, bakterije Pseudomonas aeruginosa so se izkazale za najbolj odporne. Učinkovine so vplivale na kinetiko rasti bakterij predvsem s podaljšanjem lag faze, zmanjšanjem maksimalne hitrosti rasti in znižanjem končne koncentracije celic. Dobljeni rezultati potrjujejo potencial naravnih protimikrobnih učinkovin kot alternativnega vira protimikrobnih strategij, prispevajo k boljšemu razumevanju njihovega delovanja ter možnosti uporabe v živilstvu. Antimicrobial resistance represents a major and growing challenge in both medicine and food industry, highlighting the need for alternative antimicrobial strategies. The aim of this work was to evaluate the antimicrobial activity of selected natural compounds (cinnamaldehyde, citric acid, caffeine, linalool, and nisin) against model Gram-positive (Enterococcus faecalis, Listeria innocua, Staphylococcus aureus, Streptococcus parasanguinis) and Gram-negative bacteria (Enterobacter cloacae, Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica Typhimurium). Minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) were determined using the broth microdilution method and using reagents such as resazurin and BacTiter-Glo, while bacterial growth and metabolic activity were monitored by measuring optical density. Growth kinetics were further analysed using growth curve modelling with programmes QurvE and Excel. The results demonstrated that the effectiveness of the tested compounds varied depending on the bacterial species, with cinnamaldehyde exhibiting the strongest antimicrobial activity, whereas bacteria Pseudomonas aeruginosa showed the highest level of resistance. The tested compounds primarily affected bacterial growth by prolonging the lag phase, reducing the maximum growth rate, and decreasing the final cell density. The findings confirm the potential of natural antimicrobial compounds as alternative or complementary approaches to conventional antimicrobial strategies and contribute to a better understanding of their role in addressing the increasing issue of antimicrobial resistance. protimikrobna odpornost naravne učinkovine MIK MBK rastne krivulje po Gramu pozitivne bakterije po Gramu negativne bakterije cinamaldehid citronska kislina kofein nizin antimicrobial resistance natural compounds MIC MBC growth curves Gram-positive bacteria Gram-negative bacteria cinnamaldehyde citric acid caffeine nisin true false false Slovenski jezik Angleški jezik Magistrsko delo/naloga 2026-07-05 07:17:09 2026-07-05 07:17:16 2026-07-06 12:20:05 0000-00-00 00:00:00 2026 0 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 280506 283748355 58093.pdf 58093.pdf 1 D1A4DAAC24063179B33518F41880A47E 40be1e85bd9403ef625228c56cdf9f2f058810a8c7d4b167b2dea7913874c6e2 ac32ff90-7830-11f1-9b0d-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=237026 Biotehniška fakulteta 0 0 0