Ústav chemie potravin a biotechnologií

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    Free-Standing Bacterial Cellulose/Polypyrrole Composites for Eco-Friendly Remediation of Hexavalent Chromium Ions
    (American Chemical Society, 2024-05-16) Stříž, Radim; Minisy, Islam; Bober, Patrycja; Taboubi, Oumayma; Smilek, Jiří; Kovalčík, Adriána
    Drinking water quality requirements are getting stricter but water sources are limited. Therefore, effective ways to purify it must be developed. In order to remove toxic Cr(VI) from wastewater, efficient, nontoxic, sustainable, resilient biocomposites based on bacterial cellulose (BC) and polypyrrole (PPy) have been fabricated. The free-standing BC/PPy composites, allowing easy handling during and after water treatment, were successfully prepared by the oxidative polymerization of pyrrole on the BC surface. The variation in the physical state of BC sheets used for coating by PPy was done to study the rheological properties and Cr(VI) removal capacity. Characterization techniques like FTIR, SEM, BET, thermogravimetric analysis, and rheological analyses established the morphology and structural properties of the prepared biocomposites. The physical state of the bacterial cellulose used for the coating by PPy positively affected the mechanical and thermal stabilities of the resulting BC/PPy composites but had almost no effect on the removal capacity of hexavalent chromium. The free-standing BC/PPy composites reached a specific surface area of 61.96 m2 g–1 and a pore volume of 0.097 cm3 g–1, showing more than a threefold increase compared to neat BC sheets. The coating of BC by PPy markedly improved the maximum adsorption capacity of Cr(VI). The experimental Cr(VI) adsorption data fitted using Langmuir’s isotherm model indicated homogeneous monolayer adsorption of Cr(VI) ions onto the BC/PPy surface. The Cr(VI) maximum adsorption capacity of BC/PPy composites was determined to be 294.1 mg g–1. Furthermore, the BC/PPy composites were proved to be excellent catalysts for the photocatalytic reduction of toxic Cr(VI) into nontoxic Cr(III) ions. These results suggest that the free-standing BC/PPy composites could be used as alternative materials for eco-friendly remediation of hexavalent chromium ions from wastewater.
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    Methylmercury Effect and Distribution in Two Extremophile Microalgae Strains Dunaliella salina and Coccomyxa onubensis from Andalusia (Spain)
    (MDPI, 2024-02-21) Šimanský, Samuel; Holub, Jiří; Márová, Ivana; Cuaresma, María; Garbayo Nores, Ines; Torronteras, Rafael; Vílchez, Carlos; Gojkovic, Živan
    The main entrance point of highly toxic organic Hg forms, including methylmercury (MeHg), into the aquatic food web is phytoplankton, which is greatly represented by various natural microalgal species. Processes associated with MeHg fate in microalgae cells such as uptake, effects on cells and toxicity, Hg biotransformation, and intracellular stability are detrimental to the process of further biomagnification and, as a consequence, have great importance for human health. The study of MeHg uptake and distribution in cultures of marine halophile Dunaliella salina and freshwater acidophilic alga Coccomyxa onubensis demonstrated that most of the MeHg is imported inside the cell, while cell surface adhesion is insignificant. Almost all MeHg is removed from the culture medium after 72 h. Significant processes in rapid MeHg removal from liquid medium are its abiotic photodegradation and volatilization associated with algal enzymatic activity. The maximum intracellular accumulation for both species was in 80 nM MeHg-exposed cultures after 24 h of exposure for D. salina (from 27 to 34 mu g/gDW) and at 48 h for C. onubensis (up to 138 mu g/gDW). The different Hg intakes in these two strains could be explained by the lack of a rigid cell wall in D. salina and the higher chemical ability of MeHg to pass through complex cell wall structures in C. onubensis. Electron microscopy studies on the ultrastructure of both strains demonstrated obvious microvacuolization in the form of many very small vacuoles and partial cell membrane disruption in 80 nM MeHg-exposed cultures. Results further showed that Coccomyxa onubensis is a good candidate for MeHg-contaminated water reclamation due to its great robustness at nanomolar concentrations of MeHg coupled with its very high intake and almost complete Hg removal from liquid medium at the MeHg levels tested.
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    ELEMENTAL ANALYSIS OF CZECH WINES INCLUDING WINES FROM ORGANIC PRODUCTION
    (SLOVAK UNIV AGRICULTURE NITRA, 2024-01-31) Slavíková, Zuzana; Pořízka, Jaromír; Diviš, Pavel
    Ensuring the safety of wine as worldwide major beverage commodity is of paramount importance for many control institutions and research groups. This study delves into the elemental composition of Czech wines, with a particular focus on wines from organic production, to comprehensively assess their safety in terms of elemental contaminants. The investigation aims to shed light on potential risks associated with trace elements and heavy metals in wines and to compare these risks between conventionally produced and organically produced wines. The work further focuses on major nutritionally important elements in wine. The aim of this article was screening of elemental composition (Mg, Ca, Cr, Zn, Pb, Cd, Co, Mn, Fe, Cu, Ni, Al, P) of Czech white wines (Moravia region) of different varieties and vintages. Total of 45 samples of different vintage and varieties were analyzed. 35 samples were conventionally produced, 10 samples were produced in the organic production regime. Elemental composition comparison of organic and conventional wines was evaluated. Inductively coupled plasma optical emission spectrometry (ICP-OES) was used for the analysis of wine. Analysis of variance (ANOVA) and principal component analysis (PCA) were used for the data evaluation. Results of this study extended the knowledge about the elemental composition of Czech wines and presents the comparison with wines from different important wine regions. Results showed that Czech wines are not deviating fundamentally from wines from Europe, Australia, and South America in terms of concentration of Mg, Ca, K, P, Zn, Pb, Cd, Co, Mn, Fe, Cu, Ni and Al. Important fact, connected to food safety, is that all tested wines complied with national and European legislation and with OIV limits. Statistically significant differences were found in case of Zn, Ni, Mn, Al, Cd and Mg on significancy level 0.05. Except magnesium, higher concentrations of these metals were found in samples of conventional wines. A more in-depth analysis has attributed these differences to application of synthetic pesticides, for example dithiocarbamate mancozeb.
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    Abundance of G-Quadruplex Forming Sequences in the Hepatitis Delta Virus Genomes
    (American Chemical Society, 2024-01-09) Brázda, Václav; Válková, Natálie; Dobrovolná, Michaela; Mergny, Jean-Louis
    Hepatitis delta virus (HDV) is a highly unusual RNA satellite virus that depends on the presence of hepatitis B virus (HBV) to be infectious. Its compact and variable single-stranded RNA genome consists of eight major genotypes distributed unevenly across different continents. The significance of noncanonical secondary structures such as G-quadruplexes (G4s) is increasingly recognized at the DNA and RNA levels, particularly for transcription, replication, and translation. G4s are formed from guanine-rich sequences and have been identified in the vast majority of viral, eukaryotic, and prokaryotic genomes. In this study, we analyzed the G4 propensity of HDV genomes by using G4Hunter. Unlike HBV, which has a G4 density similar to that of the human genome, HDV displays a significantly higher number of potential quadruplex-forming sequences (PQS), with a density more than four times greater than that of the human genome. This finding suggests a critical role for G4s in HDV, especially given that the PQS regions are conserved across HDV genotypes. Furthermore, the prevalence of G4-forming sequences may represent a promising target for therapeutic interventions to control HDV replication.
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    Raman spectroscopy online monitoring of biomass production, intracellular metabolites and carbon substrates during submerged fermentation of oleaginous and carotenogenic microorganisms
    (BMC, 2023-12-18) Dzurendová, Simona; Olsen, Pernille Margrethe; Byrtusová, Dana; Tafintseva, Valeria; Shapaval, Volha; Horn, Svein Jarle; Kohler, Achim; Szotkowski, Martin; Márová, Ivana; Zimmermann, Boris
    Background: Monitoring and control of both growth media and microbial biomass is extremely important for the development of economical bioprocesses. Unfortunately, process monitoring is still dependent on a limited number of standard parameters (pH, temperature, gasses etc.), while the critical process parameters, such as biomass, product and substrate concentrations, are rarely assessable in-line. Bioprocess optimization and monitoring will greatly benefit from advanced spectroscopy-based sensors that enable real-time monitoring and control. Here, Fourier transform (FT) Raman spectroscopy measurement via flow cell in a recirculatory loop, in combination with predictive data modeling, was assessed as a fast, low-cost, and highly sensitive process analytical technology (PAT) system for online monitoring of critical process parameters. To show the general applicability of the method, submerged fermentation was monitored using two different oleaginous and carotenogenic microorganisms grown on two different carbon substrates: glucose fermentation by yeast Rhodotorula toruloides and glycerol fermentation by marine thraustochytrid Schizochytrium sp. Additionally, the online FT-Raman spectroscopy approach was compared with two at-line spectroscopic methods, namely FT-Raman and FT-infrared spectroscopies in high throughput screening (HTS) setups. Results: The system can provide real-time concentration data on carbon substrate (glucose and glycerol) utilization, and production of biomass, carotenoid pigments, and lipids (triglycerides and free fatty acids). Robust multivariate regression models were developed and showed high level of correlation between the online FT-Raman spectral data and reference measurements, with coefficients of determination (R-2) in the 0.94-0.99 and 0.89-0.99 range for all concentration parameters of Rhodotorula and Schizochytrium fermentation, respectively. The online FT-Raman spectroscopy approach was superior to the at-line methods since the obtained information was more comprehensive, timely and provided more precise concentration profiles. Conclusions: The FT-Raman spectroscopy system with a flow measurement cell in a recirculatory loop, in combination with prediction models, can simultaneously provide real-time concentration data on carbon substrate utilization, and production of biomass, carotenoid pigments, and lipids. This data enables monitoring of dynamic behaviour of oleaginous and carotenogenic microorganisms, and thus can provide critical process parameters for process optimization and control. Overall, this study demonstrated the feasibility of using FT-Raman spectroscopy for online monitoring of fermentation processes.