1. Vpliv gnojenja z izrabljenim gobjim substratom na aktivnost talnih encimov v posameznih letnih časih : magistrsko deloAna Štuhec, 2024, magistrsko delo Opis: Izrabljen substrat za gobe (IGS) je stranski proizvod gojenja gob, ki sestoji iz raznovrstnih organskih materialov. Po nekaj sezonah rabe se substrat izčrpa in praviloma velja za odpadek, vendar sodobne raziskave nakazujejo številne koristne možnosti uporabe izrabljenega gobjega substrata. V projektni raziskavi se je IGS uporabljal kot organsko gnojilo na treh različnih lokacijah v ekološki, integrirani in biodinamični pridelavi paradižnika v rastlinjakih. V vsaki od pridelav se je v triplikatih testiralo gnojenje z SMS, standardno gnojenje (S), SMS+S in kontrola brez gnojenja. V sklopu magistrskega dela smo na obravnavanih lokacijah jemali vzorce zemlje v vseh letnih časih, v vzorcih pa smo analizirali aktivnost encimov N-acetil-glukozaminidaza (NAG), fosfataza (PHOS), beta-glukozidaza (β0GLU), arilsulfataza (ARS), ureaza (URE), arilamidaza (ARN), alkalna fosfataza (PAK) in kisla fosfataza (PAC) po standardu ISO 20130:2018- Kakovost tal - Merjenje encimske aktivnosti v vzorcih tal s kolorimetričnimi substrati na mikrotitrski plošči. Primerjali smo razlike v encimski aktivnosti med posameznimi letnimi časi ter med različnimi načini gnojenja. Rezultati so pokazali, da različni letni časi vplivajo na aktivnost encimov v tleh, medtem ko dodatek gobjega substrata kot gnojila ne povzroči nujno povišanja encimske aktivnosti.
Ključne besede: talni encimi, izrabljen gobji substrat, aktivnost, gnojenje, kmetijstvo
Objavljeno v DKUM: 03.09.2024; Ogledov: 52; Prenosov: 30
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2. Vpliv cemprinovega lesa na rast plesni penicillum roqueforte in asperqillus niger : magistrsko deloBranka Kristl, 2024, magistrsko delo Opis: V magistrskem delu smo testirali vpliv cemprinovega lesa na rast gliv in oblikovanje spor Aspergillus niger ter Penicillium roqueforte. Vpliv lesa smo testirali tako, da smo glive inkubirali v škatlah iz cemprinovega lesa. Kot primerjalno kontrolo za analizo rasti gliv smo uporabili še škatle iz bukovega in smrekovega lesa, plastike in čisto eterično olje
cemprina. Največji zaviralni učinek na rast testiranih gliv smo opazili v škatlah iz cemprinovega lesa, sledile so plastične škatle z dodatkom eteričnega olja cemprina. Rast gliv v drugih škatlah je bila primerljiva. Cemprinov les je imel največji zaviralni učinek na rast glive P. roqueforte, hkrati pa je zavrl tudi oblikovanje spor gliv. Cemprinov les ima zaradi svojih protiglivnih lastnosti potencial za uporabo v živilski industriji kot material
za izdelavo škatel za shranjevanje kruha in končnih pekovskih izdelkov, kjer sta pojav in kvar zaradi plesni pogosta.
Ključne besede: Pinus cembra, cemprin, Penicillium roqueforte, Aapergillus niger, protiglivno delovanje
Objavljeno v DKUM: 03.09.2024; Ogledov: 47; Prenosov: 13
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3. Probiotic mechanisms affecting glucose homeostasis : a scoping reviewMaša Pintarič, Tomaž Langerholc, 2022, pregledni znanstveni članek Opis: The maintenance of a healthy status depends on the coexistence between the host organism and the microbiota. Early studies have already focused on the nutritional properties of probiotics, which may also contribute to the structural changes in the gut microbiota, thereby affecting host metabolism and homeostasis. Maintaining homeostasis in the body is therefore crucial and is reflected at all levels, including that of glucose, a simple sugar molecule that is an essential fuel for normal cellular function. Despite numerous clinical studies that have shown the effect of various probiotics on glucose and its homeostasis, knowledge about the exact function of their mechanism is still scarce. The aim of our review was to select in vivo and in vitro studies in English published in the last eleven years dealing with the effects of probiotics on glucose metabolism and its homeostasis. In this context, diverse probiotic effects at different organ levels were highlighted, summarizing their potential mechanisms to influence glucose metabolism and its homeostasis. Variations in results due to different methodological approaches were discussed, as well as limitations, especially in in vivo studies. Further studies on the interactions between probiotics, host microorganisms and their immunity are needed.
Ključne besede: probiotic, mechanism, glucose, metabolism, homeostasis
Objavljeno v DKUM: 28.06.2024; Ogledov: 415; Prenosov: 10
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4. Antimicrobial properties of different hop (Humulus lupulus) genotypesZala Kolenc, Tomaž Langerholc, Gregor Hostnik, Miha Ocvirk, Sara Štumpf, Maša Pintarič, Iztok Jože Košir, Andreja Čerenak, Alenka Garmut, Urban Bren, 2023, izvirni znanstveni članek Opis: The antimicrobial activity of hop extracts obtained from different hop genotypes were investigated against Staphylococcus aureus and Lactobacillus acidophilus. In this study the pure xanthohumol, purified β-acids rich fraction, as well as α-acids with β-acids rich fraction were used to test antimicrobial activity against Staphylococcus aureus and Lactobacillus acidophilus; whereby, the antimicrobial activity of different hop extracts against Lactobacillus acidophilus was studied for the first time. Microbial susceptibility to purified hydroacetonic extracts from different hop varieties was investigated by the broth microdilution assay to determine the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). The hop hydroacetonic extracts were more effective against Staphylococcus aureus than against Lactobacillus acidophilus. Strong inverse correlations of MIC and MBC values were obtained with xanthohumol, cohumulone, n+adhumulone, colupulone and n+adlupulone contents, suggesting that the identified chemical hop compounds are directly responsible for antimicrobial effects. Moreover, the effect of the growth medium strength on the MIC values of hop extracts against Staphylococcus aureus was systematically investigated for the first time. The current study also reveals the effect of different hop extracts on Staphylococcus aureus, which responds to their presence by lag phase extension and generation time prolongation.
Ključne besede: hop extract, xanthohumol, Staphylococcus aureus, Lactobacillus acidophilus, minimum inhibitory concentration, minimum bactericidal concentration
Objavljeno v DKUM: 09.05.2024; Ogledov: 203; Prenosov: 11
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5. Antioxidant activity of different hop (Humulus lupulus L.) genotypesZala Kolenc, Tamara Hribernik, Tomaž Langerholc, Maša Pintarič, Maja Prevolnik Povše, Urban Bren, 2023, izvirni znanstveni članek Opis: The antioxidant activity (AA) of hop extracts obtained from different hop genotypes (n = 14) was studied. For comparison, the purified β-acids-rich fraction and α-acids-with-β-acids-rich fraction were also used to test the antioxidative potential. The AA of purified hydroacetonic hop extracts was investigated using the Ferric Reducing Ability of Plasma (FRAP), Oxygen Radical Absorption Capacity (ORAC) and Intracellular Antioxidant (IA) methods. The FRAP values in different hop genotypes ranged between 63.5 and 101.6 μmol Trolox equivalent (TE)/g dry weight (DW), the ORAC values ranged between 1069 and 1910 μmol TE/g DW and IA potential values ranged between 52.7 and 118.0 mmol TE/g DW. Significant differences in AA between hop genotypes were observed with all three methods. AAs were determined using three different methods, which did not highly correlate with each other. We also did not find significant correlations between AA and different chemical components, which applies both to AA determined using individual methods as well as the total AA. Based on this fact, we assume that the synergistic or antagonistic effects between hop compounds have a more pronounced effect on AA than the presence and quantity of individual hop compounds.
Ključne besede: hop, antioxidant activity, FRAP, ORAC, intracellular antioxidative potential, genotypes
Objavljeno v DKUM: 20.03.2024; Ogledov: 271; Prenosov: 12
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6. The Influence of Chestnut Extract and Its Components on Antibacterial Activity against Staphylococcus aureusSara Štumpf, Gregor Hostnik, Tomaž Langerholc, Maša Pintarič, Zala Kolenc, Urban Bren, 2023, izvirni znanstveni članek Opis: Increasing antimicrobial resistance has caused a great interest in natural products as alternatives or potentiators of antibiotics. The objective of this study was to isolate individual tannins from crude chestnut extract as well as to determine the influence of both crude extracts (tannic acid extract, chestnut extract) and individual pure tannins (gallic acid, vescalin, vescalagin, castalin, castalagin) on the growth of Gram-positive Staphylococcus aureus bacteria. Their antibacterial activity was monitored by measuring the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) as well as the duration of the lag phase, growth rate and generation time. The effect of growth medium strength on the MIC of different tannins was also investigated. Bacterial growth was followed spectrophotometrically, and MIC values were determined by the microdilution method. The MIC values of various isolated compounds allowed us to determine the bioactive compounds and their contribution to antimicrobial activity. It was found that MIC values increase with increasing growth medium strength and that the lag phase lengthens with increasing tannin concentrations, while the growth rates decrease. Comparing the results of the two studies, the antimicrobial activity of tannins against S. aureus was not as pronounced as in the case of E. coli, which may indicate that a different mechanism of action is responsible for the antimicrobial effects of tannins on Gram-positive than on Gram-negative bacteria, or that a different mechanism is more pronounced.
Ključne besede: tannins, antibacterial activity, MIC, MBC, Staphylococcus aureus, lag phase, generation time
Objavljeno v DKUM: 20.02.2024; Ogledov: 363; Prenosov: 58
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7. Application of Lactobacillus reuteri B1/1 (Limosilactobacillus reuteri) improves immunological profile of the non-carcinogenic porcine-derived enterocytesViera Karaffová, Jana Teleky, Maša Pintarič, Tomaž Langerholc, Dagmar Mudroňová, Erik Hudec, Zuzana Ševčíková, 2023, izvirni znanstveni članek Opis: In our previous studies, Lactobacillus reuteri B1/1, which was renamed Limosilactobacillus reuteri (L. reuteri), was able to modulate the production of pro-inflammatory cytokines and other components of the innate immune response in vitro and in vivo. In this study, we evaluated the effect of Lactobacillus reuteri B1/1 in two concentrations (1 x 10(7) and 1 x 10(9) CFU) on the metabolic activity, adherence ability and relative gene expression of pro-inflammatory interleukins (IL-1 beta, IL-6, IL-8, IL-18), lumican and olfactomedin 4 produced by non-carcinogenic porcine-derived enterocytes (CLAB). CLAB cells were cultured in a 12-well cell culture plate at a concentration of 4 x 10(5) cells/well in DMEM medium in a controlled humidified atmosphere for 48 h. A 1 mL volume of each probiotic bacterial suspension was added to the CLAB cells. Plates were incubated for 2 h and 4 h. Our results revealed that L. reuteri B1/1 was able to adhere to CLAB cells in sufficient numbers in both concentrations. In particular, the concentration of 109 L. reuteri B1/1 allowed to modulate the gene expression of pro-inflammatory cytokines, as well as to increase the metabolic activity of the cells. In addition, administration of L. reuteri B1/1 in both concentrations significantly stimulated gene expression for both proteins in the CLAB cell line after 4 h of incubation.
Ključne besede: Lactobacillus reuteri B1/1, CLAB cells, pro-inflammatory cytokine, metabolic activity
Objavljeno v DKUM: 20.02.2024; Ogledov: 273; Prenosov: 11
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8. Analiza fenolov v listih murv (Morus sp.) in njihov protibakterijski učinek : magistrsko deloŠpela Jelen, 2022, magistrsko delo Opis: V sklopu magistrskega dela smo analizirali vsebnost skupnih in posameznih fenolov v listih genotipov različnih vrst murv (Morus alba, M. alba × rubra, M. nigra, M. australis). Na podlagi fenolnega profila smo odbrali genotipe z največjimi vsebnostmi in proučili protibakterijski učinek murvovih ekstraktov na rast dveh bakterij, grampozitivne Staphylococcus aureus in gramnegativne Escherichia coli. Skupne fenole vseh genotipov smo analizirali s Folin-Ciocalteujevo metodo, posamezne fenole smo analizirali s tekočinsko kromatografijo z UV/VIS-detekcijo. Protibakterijski učinek etanolnih ekstraktov smo določali s Kirby-Bauerjevo disk difuzijsko metodo in z difuzijskim antibiogramom z vdolbinicami. Vpliv protibakterijskega učinka vodnih murvovih ekstraktov na kinetiko rasti obeh bakterij smo preučevali s pomočjo spektrofotometra na mikrotitrski ploščici. Najvišje vrednosti skupnih fenolov (21,51 ± 2 mg GAE/g SS), klorogenske kisline (14,9 ± 0,86 mg/g SS), 4-kafeoilkininske kisline (4,36 ± 0,22 mg/g SS), 5-p-kumaroilkininske kisline (2,2 ± 1,21 mg/g SS), kvercetin glikozida (0,74 ± 0,01 mg/g SS) in kemferol-acetil-heksozida (4,42 ±0,01 mg/g SS) so dosegali sadni genotipi (M. alba × rubra, M. nigra, M. australis), medtem ko so genotipi bele murve (M. alba) vsebovali največ rutina (2,67 ± 0,7 mg/g SS) in kvercetin-malonil-heksozida (1,59 ± 0,39 mg/g SS). Pri difuzijskem antibiogramu z diski inhibicijskih con pri E. coli ni bilo, medtem ko je bil pri difuzijskem antibiogramu z vdolbinicami učinek bakteriostatičen. Pri poskusu s S. aureus se je inhibicijska cona izrazila pri vseh koncentracijah murvovih ekstraktov, a je bila bakteriostatična. Na podlagi spektrofotometričnih rezultatov lahko sklepamo, da murvov ekstrakt nekaj ur zavira rast bakterij S. aureus in E. coli, nato pa jo vzpodbudi, kar lahko pripišemo proteinom in ogljikovim hidratom v ekstraktu. Za nadaljnje raziskave bi bilo smiselno uporabiti čisti fenolni ekstrakt brez beljakovin in ogljikovih hidratov, saj slednji dve snovi predstavljata hranilo za bakterije.
Ključne besede: Murve (Morus sp.), fenolni profil listov, protibakterijski učinek, S. aureus, E. coli
Objavljeno v DKUM: 07.12.2022; Ogledov: 852; Prenosov: 146
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9. Znotrajcelični antioksidativni potencial različnih sort hmelja : magistrsko deloTamara Hribernik, 2022, magistrsko delo Opis: Hmelj se tradicionalno uporablja v pivovarstvu. V zadnjih letih je bilo narejenih veliko študij o bioaktivnih molekulah hmelja, ki dokazujejo različne funkcionalne lastnosti, med njimi tudi antioksidativni potencial. V zaključni nalogi se je v pogojih in vitro določal znotrajcelični antioksidativni potencial 14 različnih sort hmelja in treh izoliranih substanc iz ekstrakta hmelja (ksantohumol, α-, β-kisline in β-kisline). Antioksidativni potencial je bil določen s pomočjo fluorescentnega barvila DCFH-DA na makrofagni celični liniji TLT. Najnižji izmerjen znotrajcelični antioksidativni potencial je bil določen pri sorti 'Savinjski golding', najvišji pa pri sorti 'Nugget'. Statistična analiza je pokazala, da med sortami hmelja obstajajo statistično značilne razlike pri znotrajceličnem antioksidativnem potencialu, in jih razdelila v pet statističnih razredov. Prav tako je bila ugotovljena statistično značilna razlika med vzorcem α-, β-kislin in vzorcem β-kislin. Zaradi neponovljivosti rezultatov so priporočljive nadaljnje raziskave o lastnostih ksantohumola. Antioksidativni potencial hmelja bi lahko v prihodnje postal eden od kriterijev pri sortni selekciji hmelja, saj je ta lastnost zanimiva za prehransko industrijo.
Ključne besede: hmelj, antioksidanti, reaktivne kisikove spojine, DCFH-DA
Objavljeno v DKUM: 15.09.2022; Ogledov: 635; Prenosov: 98
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10. Antioksidativni potencial različnih sort hmeljaTamara Kobale, 2021, magistrsko delo Opis: V magistrskem delu se je določal antioksidativni potencial različnih sort hmelja. Vzorci so bili pridobljeni s hidroacetonsko ekstrakcijo, antioksidativni potencial pa je bil določen s kemijskima metodama FRAP in ORAC. Rezultati meritev so bili analizirani s programom SPSS ob uporabi ustreznih statističnih metod. Ugotovljeno je bilo, da se različne sorte hmelja med seboj statistično značilno razlikujejo. Najvišji antioksidativni potencial po metodi FRAP je bil določen v sorti Savinjski Golding, z metodo ORAC v sortah Styrian Eureka in Aurora. Najnižji antioksidativni potencial po metodi FRAP je bil izmerjen v sorti Styrian Eureka in po metodi ORAC v sorti Caucasus. Analiza povezanosti ni pokazala značilne korelacije med rezultati metod FRAP in ORAC pri vzorcih istih sort hmelja. Antioksidativni potencial bi lahko predstavljal enega od tehnoloških parametrov za nadaljnjo selekcijo in izbor sort hmelja.
Ključne besede: Hmelj, antioksidativni potencial, FRAP, ORAC
Objavljeno v DKUM: 07.10.2021; Ogledov: 1279; Prenosov: 88
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