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11.
Determination of biogenic amine-forming potential of naturally occuring lactic acid bacteria (LAB) strains isolated from the grapes of Vitis vinifera cv. Refošk grape variety
Jelena Topić, Lorena Butinar, Martina Bergant Marušič, Dorota Korte, Branka Mozetič Vodopivec, 2020, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: Biogenic amines are naturally occurring compounds that have been reported in variety of food, such as fish, meat, cheese, vegetables, and wines. When biogenic amines are formed by microorganisms such as lactic acid bacteria (LAB) they may have adverse effect on human health. The most common biogenic amines found in foodstuff are histamine, tyramine, putrescine and cadaverine. LAB are used as starters in the production of several foods and beverages. In wines they are used in malolactic fermentation, where the conversion of malic acid to lactic acid occurs. The aim of this work was to determine biogenic amine-forming capacity of indigenous LAB strains isolated from grapes which were PCR positive and screening medium positive for biogenic amines. Three methods for the confirmation of LAB biogenic amine-forming potential were developed and compared: HPLC-DAD and TLC methods both using derivatization agent dansyl chloride and enzymatic method using horseradish peroxidase (HRP) and diamine oxidase (DAO) enzymes. The applicability of methods was tested on the three known biogenic amine-producing LAB strains: 0006, 9809, 9906 (IOEB, France). The limit of detection (LOD) of the methods was <1 mg/L for HPLC-DAD, 5 mg/L for TLC and 25 mg/L for enzymatic method. Although the LODs between the proposed methods differed, all of the three methods confirmed BA-forming potential of the three strains. Furthermore, the proposed methods were applied for the analysis of three indigenous strains: MKBT-282 (BA+), MKBT-307 (BA-) and MKBT-325 (BA+). The positive or negative BA-forming potential was confirmed with all of the three proposed methods.
Ključne besede: lactic acid bacteria, biogenic amines, histamine, grape
Objavljeno v RUNG: 10.07.2020; Ogledov: 2907; Prenosov: 0
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12.
Statistical mechanics of DNA-nanotube adsorption
Sh. A. Tonoyan, Davit Khechoyan, Yevgeni S. Mamasakhlisov, Artem Badasyan, 2020, izvirni znanstveni članek

Opis: Attraction between the polycyclic aromatic surface elements of carbon nanotubes (CNTs) and the aromaticnucleotides of deoxyribonucleic acid (DNA) leads to reversible adsorption (physisorption) between the two, aphenomenon related to hybridization. We propose a Hamiltonian formulation for the zipper model that accountsfor the DNA-CNT interactions and allows for the processing of experimental data, which has awaited an availabletheory for a decade.
Ključne besede: Carbon nanotubes, desoxyribonucleic acid, physisorption
Objavljeno v RUNG: 30.06.2020; Ogledov: 2536; Prenosov: 0
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13.
Occurence of biogenic amine - producing lactic acid bacteria in Refošk grape and wine
Jelena Topić Božič, Jan Reščič, Martina Bergant Marušič, Darja Lisjak, Branka Mozetič Vodopivec, Lorena Butinar, 2019, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: Lactic acid bacteria (LAB) are naturally present in grapes, musts and wines. During malolactic fermentation, besides the beneficial conversion of L-malic to L-lactic acid, LAB can form also other compounds like biogenic amines (BAs). BAs are formed through decarboxylation of corresponding amino acids, through the action of enzymes. Consumption of food containing BAs can lead to food poisoning such as histamine poisoning. Histamine, the most studied BA, is known to cause headaches, oedema, vomiting. In the last years, BAs associated pathways have been described as strain dependent and not as species dependent. Because of the high variability of microorganisms to decarboxylase amino acids, the detection of bacteria that have the possibility to transform precursor amino acid into BAs is very important in order to estimate the risk of BAs accumulation in wines. Since in previous years during project AGROTUR I we detected the higher BA content in some wines, we decided to focus on the presence of BA-producing LAB in Refošk grapes and wines. Therefore, during AGROTUR II project LAB collection of autochthonous lactic acid bacteria was set-up by isolating LAB from Refošk grapes and wines, originated from the grape growing cross-border region Karst (Slovenia). Over 600 isolates were obtained using MRS medium with added cycloheximide and 2% tomato juice. In parallel, also selective enrichment was performed using MRS medium described above with additionally added 5% ethanol. BA-producing LAB were primarily detected in microtiter-plate format using the decarboxylase screening medium with added amino acids (histidine, lysine, ornithine or tyrosine), which enable us to identify histamine-, cadaverine-, ornithine and tyrosine-producing LAB. Selected representatives from each BA-producing LAB groups were further on confirmed with chromatographic analysis (HPLC) and molecular methods (multiplex PCR method). BA-producing LAB were in majority represented by thyramin-producers, thereafter followed cadaverine-producers, with putrescine and histamine producers being the least presented. This screening of the BA-producing LAB is also incorporated in our on-going accurate selection of LAB starters for potential production of Refošk wines.
Ključne besede: biogenic amines, lactic acid bacteria, refošk, grape, wine
Objavljeno v RUNG: 22.01.2020; Ogledov: 3251; Prenosov: 0
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14.
SIGNALING STUDIES IN THE EMERGING KIWIFRUIT PATHOGEN Pseudomonas syringae pv. actinidiae
Sree Gowrinadh Javvadi, 2017, doktorska disertacija

Opis: In the past two decades emerging and re-emerging plant pathogens have caused new threats to the production of several economically important crops, one among them is P. syringae pv. actinidiae (PSA) which causes canker or leaf spot on kiwifruit plants. PSA enters plant through wounds and remains dormant in cortex tissue of the branches, and spreads in the tissue to cause severe symptoms from winter to early spring. The disease can be visualized by brown discoloration of buds, dark brown angular spots surrounded by yellow haloes on leaves, cankers with white to reddish (oxydation) exudate on twigs and trunks, fruit collapse, wilting and eventually plant mortality. Current control methods have their own significance in disease control, however there is considerable lack of clear understanding of PSA pathogenicity. Virulence of plant pathogens often relies on the synchronized/coordinated expression of pathogenicity factors via quorum sensing (QS). Therefore, investigations on QS in PSA may lead to develop novel disease control strategies and reliable methods to curb the disease. It is currently unknown whether PSA produces a QS signal molecule thus the aim of this thesis is to investigate whether PSA possesses a QS system. As genome mining did not reveal the presence of any currently known QS system, this study initially by metabolomics was aimed at identifying potentially low molecular weight secondary metabolite QS molecules produced by PSA. Azelaic acid was discovered to be produced by PSA, this is the first report of azelaic acid production by bacteria. The characterization and possible role of azelaic acid in QS is presented. Since azelaic acid is ubiquitous in nature, in addition to determining its biological role, the catabolism of azelaic acid in bacteria using the efficient degrader Pseudomonas nitroreducens DSM 9128 was also studied.
Ključne besede: Quorum sensing, Azelaic acid, Metabolomics, Catabolism
Objavljeno v RUNG: 19.12.2017; Ogledov: 4619; Prenosov: 212
.pdf Celotno besedilo (4,41 MB)

15.
Oxalic acid adsorption states on the clean Cu(110) surface
Sara Fortuna, 2016, izvirni znanstveni članek

Opis: Carboxylic acids are known to assume a variety of configurations on metallic surfaces. In particular oxalic acid on the Cu(110) surface has been proposed to assume a number of upright configurations. Here we explore with DFT calculations the possible structures that oxalic acid can form on copper 110 at different protonation states, with particular attention at the possibility of forming structures composed of vertically standing molecules. In its fully protonated form it is capable of anchoring itself on the surface thanks to one of its hydrogen-free oxygens. We show the monodeprotonated upright molecule with two oxygens anchoring it on the surface to be the lowest energy conformation of a single oxalic molecules on the Cu(110) surface. We further show that it is possible for this configuration to form dense hexagonally arranged patterns in the unlikely scenario in which adatoms are not involved.
Ključne besede: oxalic acid, oxalate, cu(110), copper, surface, adsorption, density functional theory, DFT
Objavljeno v RUNG: 11.10.2016; Ogledov: 4441; Prenosov: 0
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16.
Agent based modelling for the 2D molecular self-organization of realistic molecules
Sara Fortuna, Alessandro Troisi, 2010, izvirni znanstveni članek

Opis: We extend our previously developed agent-based (AB) algorithm to the study of the self-assembly of a fully atomistic model of experimental interest. We study the 2D self-assembly of a rigid organic molecule (1,4-benzene-dicarboxylic acid or TPA), comparing the AB results with Monte Carlo (MC) and MC simulated annealing, a technique traditionally used to solve the global minimization problem. The AB algorithm gives a lower energy configuration in the same simulation time than both of the MC simulation techniques. We also show how the AB algorithm can be used as a part of the protocol to calculate the phase diagram with less computational effort than standard techniques.
Ključne besede: self-assembly, self-organisation, 1, 4-benzene-dicarboxylic acid, TPA, agent based, Monte Carlo, simulation, phase diagram
Objavljeno v RUNG: 11.10.2016; Ogledov: 4761; Prenosov: 0
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17.
Hexagonal lattice model of the patterns formed by hydrogen-bonded molecules on the surface
Sara Fortuna, David L. Cheung, Alessandro Troisi, 2010, izvirni znanstveni članek

Opis: We model the two-dimensional self-assembly of planar molecules capable of complementary interactions (like hydrogen bonding) as a set of hexagonal tiles on a hexagonal lattice. We use Monte Carlo simulations to study the phase diagrams of three model systems. The phases are characterized using a variety of order parameters, and they are studied as a function of the strength of the complementary interaction energy. This simplified model is proven to be capable of reproducing the phases encountered in real systems, unifying within the same framework most of the structures encountered experimentally.
Ključne besede: self-assembly, self-organisation, Monte Carlo, simulation, lattice model, dicarboxilic acid, hexagonal lattice
Objavljeno v RUNG: 10.10.2016; Ogledov: 4757; Prenosov: 0
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18.
Design of a highly photocatalytically active ZnO/CuWO4 nanocomposite
Matjaž Valant, 2016, izvirni znanstveni članek

Ključne besede: Photocatalysis Heterostructure Nanocomposite Methyl orange Terephthalic acid
Objavljeno v RUNG: 08.09.2016; Ogledov: 4738; Prenosov: 0
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19.
Efficient mineralization of aqueous organic pollutants by photocatalytic ozonation
Urška Lavrenčič Štangar, Marko Kete, predavanje na tuji univerzi

Opis: Photocatalytic ozonation process using TiO2 photocatalyst (O3/TiO2/UV – PH-OZ) conducted in acidic water environment often leads to synergistic effect in terms of decomposition and mineralization of aqueous organic contaminants, which makes the process suitable for waste water treatment or pretreatment of drinking water. [1,2] The synergism is among other factors (pH, O3 dose, T,…) greatly influenced by photocatalyst physicochemical properties and pollutant type. In the first part of the study, five different commercial TiO2 photocatalysts (P25, PC500, PC100, PC10 and JRC-TiO-6) were used in O2/TiO2/UV, O3/TiO2 and O3/TiO2/UV advanced oxidation systems for degradation of two pollutants (dichloroacetic acid - DCAA and thiacloprid – neonicotinoid pesticide), simultaneously present in water solution. [3] Results of PH-OZ (O3/TiO2/UV) experiments showed that in contrast to DCAA which adsorbs on TiO2 surface, synergistic effect is much more expressed in the case of thiacloprid which doesn’t adsorb. The influence of BET surface area of the photocatalyst and its dispersivity will be discussed. In the second part of this study, selected catalysts were immobilized on a proper support to avoid post-filtration step in the process of greywater treatment. A good adhesion of a catalyst on various supports was successfully achieved by immobilization of commercial TiO2 powders (P25, P90, PC500) with the help of a sol-gel silica-titania binder [4]. For the purpose of simulated greywater treatment, special compact reactor was designed and developed, utilizing Al2O3 porous reticulated monolith foams as TiO2 carriers and UVA-lamps inside (Fig. 1). [5] With degradation of LAS+PBIS and Reactive blue 19 (RB 19) as representatives of surfactants and textile dyes respectively, commonly found in household greywater, and phenol as trace contaminant, an evaluation of PH-OZ and photocatalytic oxidation has been performed (an example in Fig. 2). Synergistic effect of PH-OZ was generally much more expressed in mineralization reactions, showing TOC half lives of less than one hour for the mixture of pollutants in compact reactor. [5] Due to its superior cleaning capacity, PH-OZ process employing efficient photocatalysts is suitable for treating wastewaters also with higher loading of organic pollutants. 1. U. Černigoj, U.Lavrenčič Štangar, J. Jirkovsky, J. Hazard. Mater. (2010) 177:399–406. 2. U. Černigoj, U.Lavrenčič Štangar, P. Trebše, Appl. Catal. B Environ. (2007) 75:229–238. 3. M. Kete, U. Černigoj, U. Lavrenčič Štangar: Photocatalytic ozonation – study of reaction parameters and mechanism, article under submission 4. M. Kete, E. Pavlica, F. Fresno, G. Bratina, U. Lavrenčič Štangar, Environ. Sci. Pollut. Res. (2014) 21:11238–11249. 5. M. Kete: Towards efficient removal of contaminants in water from household appliances by TiO2-photocatalysis: design, optimization and performance studies of the photoreactor with immobilized catalysts, Doctoral dissertation (2015), University of Nova Gorica, Nova Gorica.
Ključne besede: photocatalysis, ozonation, TiO2, dichloroacetic acid, thiacloprid, mechanisms, LAS+PBIS, Reactive blue 19, phenol
Objavljeno v RUNG: 21.07.2016; Ogledov: 6760; Prenosov: 0
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20.
Reducing treatments in cattle superovulation protocols by combining a pituitary extract with a 5% hyaluronan solution: Is it able to diminish activation of the hypothalamic pituitary adrenal axis compared to the traditional protocol?
Andrea Biancucci, Tatiana Sbaragli, Antonella Comin, Lakamy Sylla, Maurizio Monaci, Tanja Peric, Giuseppe Stradaioli, 2016, izvirni znanstveni članek

Opis: Traditional superovulation protocols that include multiple gonadotropin treatments are time-consuming and labor intensive. These protocols require multiple handling and restraining of embryo donors. This will likely increase the risks of injuries in both animals and humans and induce stress that may lead to a reduced superovulatory response. These are more evident when working with cattle that are rarely handled or raised on extensive grazing. The objectives of this experiment were to compare the efficacy of a split-injection protocol of porcine pituitary-derived porcine FSH (pFSH) preparation (slow release [SR] group) to the traditional 4-day treatment with pFSH administered twice daily (C group) and to determine the concentrations of cortisol in the hair as a marker of activation of the hypothalamic-pituitary-adrenal (HPA) axis during the two superovulatory treatments. Thirty-two heifers were stimulated twice in a 2 × 2 crossover design and compared for ovarian response and numbers and characteristics of recovered ova-embryo among treatments. No differences between SR and C groups were found in terms of percentage of responsive animals (100% vs. 93.8%) and ovulation rate (83.7 ± 1.1 vs. 79.5 ± 1.0%). A positive correlation was found between the number of follicles responsive to pFSH (2-8 mm) at the beginning of treatments and the superovulatory response, and no differences were found in these follicular populations between the two treatment groups. The numbers of CLs, ova-embryos, fertilized ova, transferable and freezable embryos recovered per cow were found to be significantly higher in SR compared with C group (14.0 ± 1.6 vs. 10.6 ± 1.0, 12.1 ± 1.6 vs. 7.6 ± 1.0, 11.1 ± 1.1 vs. 7.3 ± 1.0, 9.6 ± 1.4 vs. 6.6 ± 1.0, and 9.4 ± 1.4 vs. 6.0 ± 1.0 for SR and C group, respectively). The SR group produced also a significantly greater number of excellent- and/or good-quality embryos compared with the C group. The concentrations of cortisol in the hair at Days 14 and 21 were significantly greater in the C compared with the SR group (P < 0.05). In conclusion, these results indicate that the dilution of gonadotropin in a 5% hyaluronan solution, reducing the administration frequency, improves the quantitative and qualitative superovulatory response of Marchigiana heifers. Further studies using other breeds of cattle are needed to verify the results herein obtained and to confirm the lower activation of the hypothalamic-pituitary-adrenal axis caused in the donor by the split-injection protocol.
Ključne besede: Beef heifer, Bovine, Hair cortisol, Hyaluronic acid, Slow release, Superovulation
Objavljeno v RUNG: 01.03.2016; Ogledov: 4479; Prenosov: 312
.pdf Celotno besedilo (403,15 KB)
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