20.500.12556/RUL-188743 Izolacija zunajceličnega matriksa biofilma bakterij Pseudomonas lundensis in njegov vpliv na površinske lastnosti mikroplastike Isolation of extracellular polymeric substances from Pseudomonas lundensis biofilm and its effect on surface properties of microplastics Na površino mikroplastike se veže organska snov, ki značilno vpliva na njene fizikalno-kemijske lastnosti. V sklopu tega magistrskega dela smo preverili, kako zunajcelični matriks biofilma bakterij Pseudomonas lundensis, povezanih s kvarom piščančjega mesa, vpliva na površinske lastnosti mikroplastike, pripravljene iz folije za pakiranje živil na osnovi polietilen tereftalata. Zunajcelični matriks smo izolirali z uporabo treh različnih metod: centrifugiranja (B), metode z natrijevim karbonatom (C) ter metode s formaldehidom in NaOH (F). Njegovo sestavo smo ovrednotili glede na vsebnost polisaharidov, proteinov in zunajcelične DNA. Mikroplastiko smo inkubirali v izolatih zunajceličnega matriksa in nato spremembe v njenih površinskih lastnostih ovrednotili z meritvami kontaktnega kota, rentgensko fotoelektronsko spektroskopijo (XPS) in masno spektrometrijo sekundarnih ionov s časom preleta (ToF-SIMS). Ugotovili smo, da izbira metode izolacije pomembno vpliva na vsebnost posameznih komponent v izolatu. Ostanki zunajceličnega matriksa na mikroplastiki so vplivali na povečanje proste površinske energije, pri čemer so bile statistično značilne razlike ugotovljene pri zunajceličnem matriksu, izoliranem z metodama C in F. Analizi XPS in ToF-SIMS sta potrdili spremembe v kemijski sestavi površine mikroplastike. Rezultati kažejo, da je vpliv zunajceličnega matriksa biofilma bakterij P. lundensis na površinske lastnosti mikroplastike odvisen od njegove biokemijske sestave ter da zunajcelični matriks prispeva k nastanku organskih kondicionirnih plasti, katerih lastnosti se med posameznimi izolati matriksa razlikujejo. Organic matter adsorbs onto microplastic surfaces, substantially affecting their physicochemical properties. In this master’s thesis, we investigated the effects of extracellular polymeric substances (EPS) derived from biofilms of Pseudomonas lundensis, a psychrotrophic bacterium associated with chicken meat spoilage, on the surface properties of microplastics prepared from polyethylene terephthalate-based food packaging foil. EPS was isolated using three methods: centrifugation (B), sodium carbonate treatment (C), and formaldehyde/NaOH treatment (F). The composition of the resulting EPS isolates was evaluated based on their polysaccharide, protein, and extracellular DNA contents. Microplastics were incubated in the EPS isolates, after which changes in their surface properties were assessed by contact angle measurements, X-ray photoelectron spectroscopy (XPS), and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The isolation method significantly affected the content of individual components in the EPS isolates. The presence of EPS residues on the microplastic surfaces increased the surface free energy, with statistically significant differences observed for EPS isolated using methods C and F. XPS and ToF-SIMS analyses further confirmed changes in the chemical composition of the microplastic surface. Overall, the results indicate that the effects of P. lundensis biofilm EPS on microplastic surface properties depend on its biochemical composition, and that EPS contributes to the formation of organic conditioning layers whose characteristics differ among individual EPS isolates. zunajcelični matriks biofilm Pseudomonas lundensis mikroplastika površinske lastnosti varnost živil extracellular polymeric substances biofilm Pseudomonas lundensis microplastics surface properties food safety true false false [T. Šaula] Slovenski jezik Angleški jezik Magistrsko delo/naloga 2026-09-27 07:15:53 2026-09-27 07:15:57 2026-09-28 10:47:22 0000-00-00 00:00:00 2026 0 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 2027-09-23 579.6:614.31:504.5:678.5/.7:620.1 292646 292675331 63547.pdf 63547.pdf 1 C5AC8C8B812440BE23631F48499083E3 1e3c02e78f7cc0b304ad4b8377802a87e9fb060aebe26cc015503876666c4aeb 719cdb50-ba32-11f1-8bc5-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=249069 Biotehniška fakulteta 0 0 0