In recent years, the geographical authentication of different agro-products, including vegetables, has gained an increasing amount of attention. This study investigated different approaches, both ...independently and in combination, to assign the country of origin to commercial tomato samples from Slovenia, Italy, Spain and Morocco. To create a model for their traceability, three sets of parameters were used: stable isotopes of the major bioelements (δ13C, δ15N, δ18O, δ34S), macro and micro elements (P, K, Ca, S, Cl, Zn, Br, Rb, Sr), and chemical markers (total antioxidant potential, total phenolic compounds, ascorbic acid, lutein, nitrates and nitrites, ammonium). The data obtained were analysed using the supervised pattern-recognition technique of multivariate discriminant analysis. The statistical analysis based on leave-one-out cross-validation revealed that the best overall success rate was achieved when using either the combination of all three sets of parameters, or only the elemental content data. In both cases, correct classification was obtained for 80% of the samples. Moreover, the present study highlights the first characterisation and classification of commercial tomato samples using the combination of the methodologies proposed.
•Different approaches to assign the country of origin to commercial tomato samples.•Three sets of parameters were used: stable isotopes, elements, and chemical markers.•The first use of the combination of proposed parameters.•The elemental data provides the same predictive power as the combined data from all three approaches.•In both cases, correct classification was obtained for 80% of samples.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Organic crop production has become a highly attractive way of production over the world and thus the need for robust analytical techniques for their authentication. The main aim of this study is to ...identify appropriate biomarkers to discriminate between organic and conventionally grown chicory. Chicory is an appreciated leafy vegetable among producers and consumers, especially due to its undemanding cultivation and content of bioactive substances. Six different fertility management practices (control, two organic, two mineral, and a combination of organic and mineral fertilizers) were used to produce five chicory cultivars in a glasshouse pot experiment. Analysis of bioactive compounds, nitrogen assimilation, multi-elemental profiling and stable isotope ratio determination of carbon (C), nitrogen (N) and sulphur (S) were performed to differentiate between organic and conventional production. In this study, nitrogen isotopes are found to be an excellent way of identifying organically produced chicory of a different variety with the highest δ15N values. Conversely, the same samples had the lowest δ34S values indicating that also stable isotopes of S could be used as a marker for the authentication of organic production.
•Five chicory cultivars were grown in a pot experiment.•Six different fertility management practices were applied.•Differences in bioactive compounds content and nitrogen assimilation were evaluated.•Multi-elemental profiling and stable isotope ratios of light elements were studied.•Parameters to discriminate organic and conventionally grown chicory were identified.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Prodigiosin produced by marine bacterium Vibrio ruber DSM 14379 exhibits a potent antimicrobial activity against a broad range of Gram positive and Gram negative bacteria. The mechanism of ...prodigiosin antimicrobial action, however, is not known. In this work, the effect of prodigiosin on Bacillus subtilis growth, cell membrane leakage, and induction of autolysins was studied. Treating B. subtilis with prodigiosin resulted in rapid decline of optical density and increased cell membrane leakage measured by β-galactosidase activity. Cell lysis was initiated immediately after treatment with prodigiosin in the middle exponential phase and was completed within 2 h. Lytic activity of prodigiosin in mutant strains with impaired autolysin genes lytABCD decreased for 80% compared to the wild type strain, while in lytABCDEF mutant strain prodigiosin had no bacteriolytic but only bacteriostatic effect. Fast prodigiosin lytic activity on individual B. subtilis cells was confirmed by a modified comet assay. The results indicate that prodigiosin autolysin induction in B. subtilis is growth phase dependent.
Peatlands play an important role in emissions of the greenhouse gases CO2, CH4 and N2O, which are produced during mineralization of the peat organic matter. To examine the influence of soil type ...(fen, bog soil) and environmental factors (temperature, groundwater level), emission of CO2, CH4 and N2O and soil temperature and groundwater level were measured weekly or biweekly in loco over a one-year period at four sites located in Ljubljana Marsh, Slovenia using the static chamber technique. The study involved two fen and two bog soils differing in organic carbon and nitrogen content, pH, bulk density, water holding capacity and groundwater level. The lowest CO2 fluxes occurred during the winter, fluxes of N2O were highest during summer and early spring (February, March) and fluxes of CH4 were highest during autumn. The temporal variation in CO2 fluxes could be explained by seasonal temperature variations, whereas CH4 and N2O fluxes could be correlated to groundwater level and soil carbon content. The experimental sites were net sources of measured greenhouse gases except for the drained bog site, which was a net sink of CH4. The mean fluxes of CO2 ranged between 139 mg m−2 h−1 in the undrained bog and 206 mg m−2 h−1 in the drained fen; mean fluxes of CH4 were between −0.04 mg m−2 h−1 in the drained bog and 0.05 mg m−2 h−1 in the drained fen; and mean fluxes of N2O were between 0.43 mg m−2 h−1 in the drained fen and 1.03 mg m−2 h−1 in the drained bog. These results indicate that the examined peatlands emit similar amounts of CO2 and CH4 to peatlands in Central and Northern Europe and significantly higher amounts of N2O.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The polysaccharide levan is a homopolymer of fructose and appears in nature as an important structural component of some bacterial biofilms. This paper reports the structural and dynamic properties ...of aqueous solutions of levan of various origin obtained from dynamic rheological, small-angle X-ray scattering, static and dynamic light scattering, as well as density and sound velocity measurements, determination of polymer branching after per-O-methylation, and microscopy. Besides samples of commercially available levan from Zymomonas mobilis and Erwinia herbicola, we also isolated, purified, and studied a levan sample from the biofilm of Bacillus subtilis. The results of dynamic rheological and light scattering measurements revealed very interesting viscoelastic properties of levan solutions even at very low polymer concentrations. The findings were complemented by small-angle X-ray scattering data that revealed some important differences in the structure of the aqueous levan solutions at the molecular level. Besides presenting detailed dynamic and structural results on the polysaccharide systems of various levans, one of the essential goals of this work was to point out the level of structural information that may be obtained for such polymer systems by combining basic physicochemical, rheological, and various light scattering techniques.
Full text
Available for:
IJS, KILJ, NUK, PNG, UL, UM
Extracellular polymeric substances (EPS) play an important role in cell aggregation, cell adhesion, and biofilm formation, and protect cells from a hostile environment. The EPS was isolated by ...trichloroacetic acid/ethanol extraction from broth culture of a marine bacterium isolate. The EPS was composed of glucose and galactose as determined by HPLC and TLC; the protein content was on average 15
±
5% of EPS dry mass. The solution structure of EPS at different values of pH was revealed by small-angle x-ray scattering. Scattering curves of EPS solutions (0.4%, w/v) consistently showed two nearly linear log-log regions with slopes
a and
b in the
q-ranges from 0.06
nm
−1 to 0.26
nm
−1, and from 0.27
nm
−1 to 0.88
nm
−1, respectively. Slope
a was sensitive to pH changes whereas slope
b was not. The observed sensitivity to pH was not a consequence of ionic strength variation with pH, as checked by salt addition. The pH variation causes major rearrangements of EPS structure mainly at length scales above 24
nm. To get a better understanding of the pH effect on EPS structure, the original model proposed by Geissler was refined into a mathematical model that enabled fitting of the experimental scattering curves in the pH range from 0.7 to 11.0. The model describes EPS structure as a network of randomly coiled polymeric chains with denser domains of polymeric chains. The results obtained from the model indicate that dense domains increase in average size from 19
nm at pH 11.0 to 52
nm at pH 0.7. The average distance between the polysaccharide chains at pH 0.7 was 2.3
nm, which indicates a compact EPS structure. Swelling was found to be at a maximum around pH
=
8.8, where the average distance between the chains was 4.8
nm.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•A new tosylic ester of CMC was prepared with anhydride of p-toluensulphonic acid.•The TsCMC has higher viscosity and pseudoplasticity compared to parental CMC.•It has superior emulsification ...properties and decreased wettability compared to parental CMC.•The biodeterioration of TsCMC was significantly reduced compared to parental CMC.•TsCMC biodeteriorated less compared to commercially used modified cellulose thickeners.
Microbial biodegradation and biodeterioration of cellulose based thickeners is a serious problem in industry. A new tosylic ester of carboxymethyl cellulose (TsCMC) was prepared with anhydride of p-toluensulphonic acid. The TsCMC has improved rheological properties, higher viscosity and pseudoplasticity, superior emulsification properties and decreased wettability compared to parental CMC. The biodeterioration of TsCMC was significantly reduced compared to parental CMC or other commercially used modified cellulose thickeners in water based paint industry. Improved rheological properties combined with low biodeterioration make TsCMC a promising new material for industrial applications with a potential to reduce the use of hazardous antimicrobial agents.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Temperature is an important environmental factor which can dramatically affect biochemical processes in bacteria. Temperatures above optimal cause heat shock, while low temperatures induce cold ...shock. Since the physiological response of the bacterium Escherichia coli to slow temperature fluctuation is not well known, we investigated the effect of periodic temperature cycling between 37° and 8°C with a period of 2 h on proteome profile, cold shock CspA and CspB protein and gene production.
Several proteins (i.e. succinyl-CoA synthetase subunit alpha, periplasmic oligopeptide-binding protein, maltose-binding periplasmic protein, outer membrane porin protein, flavodoxin-1, phosphoserine aminotransferase) were up or down regulated during temperature cycling, in addition to CspA and CspB production. The results indicate that transcription of cspA and cspB increased during each temperature downshift and consistently decreased after each temperature upshift. In sharp contrast CspA-FLAG and CspB-FLAG protein concentrations in the cell increased during the first temperature down-shift and remained unresponsive to further temperature fluctuations. The proteins CspA-FLAG and CspB-FLAG were not significantly degraded during the temperature cycling.
The study demonstrated that slow periodic temperature cycling affected protein production compared to cells constantly incubated at 37°C or during classical cold shock. Bacterial cspA and cspB mRNA transcript levels fluctuated in synchrony with the temperature fluctuations. There was no corresponding pattern of CspA and CspB protein production during temperature cycling.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Melamine resins are extensively used as chemical consolidate agents in the preservation of different waterlogged archaeological wood artifacts. For successful consolidation, it is essential to ...control the rate of melamine polymerization. Currently, the understanding of melamine polymerization in waterlogged archaeological wood is qualitative, and is based on the experiences and skills of the conservators-restorers. In this study, we have tested different environmental conditions and additives that influence the rate of Kauramin 800 polymerization in waterlogged archaeological wood by Fourier transform infrared (FTIR) spectroscopy. The results show a fast polymerization reaction of Kauramin 800 at pH values below 7. The polymerization rate of Kauramin 800 increased in the presence of glycine and archaeological wood. On the other hand, slower polymerization was observed with the addition of Kraft lignin. The results indicate that FTIR spectroscopy is a powerful tool in monitoring the process of Kauramin 800 polymerization during the preservation of archaeological waterlogged wood.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Pigments such as melanin, scytonemin and carotenoids protect microbial cells against the harmful effects of ultraviolet (UV) radiation. The role in UV protection has never been assigned to the ...prodigiosin pigment. In this work, we demonstrate that prodigiosin provides a significant level of protection against UV stress in Vibrio sp. DSM 14379. In the absence of pigment production, Vibrio sp. was significantly more susceptible to UV stress, and there was no difference in UV survival between the wild-type strain and non-pigmented mutant. The pigment's protective role was more important at higher doses of UV irradiation and correlated with pigment concentration in the cell. Pigmented cells survived high UV exposure (324 J/m²) around 1,000-fold more successfully compared to the non-pigmented mutant cells. Resistance to UV stress was conferred to the non-pigmented mutant by addition of exogenous pigment extract to the growth medium. A level of UV protection equivalent ot that exhibited by the wild-type strain was attained by the non-pigmented mutant once the prodigiosin concentration had reached comparable levels to those fond in the wild-type strain. In co-culture experiments, prodigiosin acted as a UV screed, protectin both the wild-type and non-pigmented mutants. Our results suggest a new ecophysiological role for prodigiosin. '
Full text
Available for:
BFBNIB, EMUNI, NMLJ, NUK, PNG, SAZU, SBMB, SBNM, UL, UM, UPUK
PDF
