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Biogenesis, redox properties and catalytic activity of Mn-O-Ca cluster from the green microalga Chlorella sorokiniana
No full textManganese is an essential element for green microalga Chlorella sorokiniana required for
photosynthesis as a component of the oxygen-evolving complex (OEC) in photosystem II, but
can be toxic in higher concentrations. We have previously shown by EXAFS and XANES that
C. sorokiniana accumulates Mn in the form of a multivalent Mn-O-Ca cluster resembling the
structure of the tetramanganese-calcium core of the OEC in photosystem II with Mn in various
oxidation states (+2, +3, +4), when grown in Mn-enriched medium (1 mM).[1]. In this work, the
metabolism of Mn in C. sorokiniana was further investigated. 31P NMR spectroscopy showed
that polyphosphates, most likely from the cell wall, are involved in the transient chelation of Mn
in the early phase of microalgal response. NanoXFM identified acidocalcisomes as the final
compartment of Mn accumulation, where most of the intracellular Mn was stored.
Perpendicular mode low-T EPR showed that the spin of Mn in the cluster is >1/2, while the
parallel mode did not provide any resolvable signal above the noise level, indicating that the
spin of Mn is not an integer. To test potential catalytic activities of the cluster, crude extract of
C. sorokiniana was prepared.[2]. The presence of the cluster in the extract was confirmed by
cyclic and differential pulse voltammetry, which showed same oxidation states of Mn in the
cluster as XANES did with biomass, with peak potentials similar to those in OEC model
compounds.[3]. The catalase and OEC mimetic catalytic activities of the cluster were tested
using oximetry. Like the catalase, the cluster enhanced the disproportionation of H2O2 to H2O
and O2, but decayed during the process, acting as a reagent, rather than a catalyst. OEC
mimetic activity was studied using Ce(IV) ions as single-electron oxidation agent to drive the
water-oxidation reaction, but instead of expected O2 production, Ce(IV) led to O2 depletion. A
more detailed analysis of OEC mimetic activity of the Mn-O-Ca cluster induced by other
oxidation agents is warranted
EARLY SELECTION OF MOST APPROPRIATE POPLAR AND WILLOW CULTIVARS FOR LANDFILL REMEDIATION USING PLANT PHYSIOLOGY PARAMETERS
No full textThe effect of landfills on the environment reflects the dispersion of the contaminants on surrounding soils
by the groundwater plume. Such negative effect can be mitigated with the establishment of vegetative
buffers surrounding landfills. The “TreeRemEnergy” project funded by the Science Fund of Republic of
Serbia – Green program focuses on development of phyto-buffers for landfill phytoremediation with
the use of Short Rotation Woody Crops (SRWC) plantations that can be further used for the biomass
for energy. One of the goals of the project is to select the most appropriate poplar (Populus sp.) and
willow (Salix sp.) clones through phytorecurrent selection that involves testing of various breeding
traits. Physiological parameters serve as a significant contribution to the breeding process aimed at
early detection of potential candidates. This study involved testing the effect of the landfill soils on the
photosynthetic processes of the selected poplar and willow candidates in greenhouse pot trial. For
this purpose, measurements of the gas exchange, chlorophyll content and chlorophyll fluorescence
were measured on the tested plants. There was significant effect of interaction Clone×Substrate in
intercellular CO2 concentration(ci), stomatal conductance (gs) and transpiration rate (E), suggesting
that water regime of the tested clones differed considering tested substrates. Some clones showed
more “generalist” behavior (380, 107/65/9, and PE19/66), while “specialist” behavior was recorded in
clones PE4/68, S1-8, and 79/64/2. On the other hand, there was no significant effect of the tested
substrate on the pigments content measured with SPAD meter. Results of this study allowed us to
narrow the group of clones for further trails in field condition
KOSAGOREVANJE KONTAMINIRANE BIOMASE VRBA (SALIX L.) SA LIGNITOM U PROCESU PROIZVODNJE ENERGIJE
No full textThe share of renewable energy sources (RES) in energy production
processes is growing every day in many countries. Globally, there is a very pronounced
tendency to eliminate fossil fuels for energy production, which are replaced by RES. The
path to decarbonization involves the successive reduction of fossil fuels and their
replacement by RES. One of the possibilities of using RES, which could be used in co-firing
processes with coal, is biomass obtained from fast-growing woody species, such as poplars
and willows. Willows, as effective hyperaccumulators of heavy metals, successfully
remediate the soil, producing biomass that can be used in energy production, both
independently and through co-firing with coal. The aim of this paper is to determine the
energy potential of contaminated willow biomass, as well as to determine the most
favourable type of willow that would be used to improve the calorific value of lignite in cofiring processes, in different percentage ratios. The biomass obtained from willows
contaminated with heavy metals (Cd, Cu, Cr, Ni, Pb and As) is characterized by a higher
calorific value than the value of the examined lignite samples. Two types of willows, basket
willow (Salix viminalis) and white willow (S. alba), clone B-44, as well as three coal
samples, sampled from three different locations in Kolubara Mining Basin, Elektroprivreda
Srbije AD, were examined. The obtained results indicate the dependence of the calorific
value of lignite on the coal deposit, while the calorific value of willow depends on the type
of willow. White willow (clone B-44) has a higher energy potential than basket willow, and
co-firing processes are economically justified, if lower percentage ratios (about 10%) of
biomass were used.Uvećanje procenta upotrebe obnovljivih izvora energije (OIE) u
procesima proizvodnje energije svakim danom raste u mnogim zemljama. U svetu je veoma
izražena tendencija eliminacije fosilnih goriva za proizvodnju energije, čiju supstituciju
vrše OIE. Put ka dekarbonizaciji uključuje sukcesivno umanjivanje fosilnih goriva i njihovu
zamenu OIE. Jedna od mogućnosti upotrebe OIE, koja bi mogla da se koristi u procesima
kosagorevanja sa ugljem, predstavlja biomasa dobijena od brzorastućih drvenastih vrsta,
kao što su topole i vrbe. Vrbe, kao dobri hiperakumulatori teških metala, uspešno vrše
rekultivaciju zemljišta, proizvodeći biomasu koja se može upotrebiti u proizvodnji energije,
kako samostalno, tako i kroz kosagorevanje sa ugljem. Cilj ovog rada je utvrđivanje
energetskog potencijala biomase kontaminiranih vrba, kao i utvrđivanje najpovoljnije vrste
vrba koja bi se koristila za poboljšanje kalorijske vrednosti lignita u procesima
kosagorevanja, u različitim procentualnim odnosima. Biomasu, dobijenu od vrba
kontaminiranim teškim metalima (Cd, Cu, Cr, Ni, Pb i As), karakteriše veća kalorijska
vrednost od vrednosti ispitivanih uzoraka lignita. Ispitivane su dve vrste vrba, košarasta
vrba (Salix viminalis) i bela vrba (S. alba), klon B-44, kao i tri uzorka uglja, uzorkovana sa
tri različita lokaliteta u RB Kolubara, Elektroprivreda Srbije AD. Dobijeni rezultati
ukazuju na zavisnost kalorijske vrednosti lignita od ležišta uglja, dok je kalorijska vrednost
vrba zavisna od vrste vrba. Bela vrba (klon B-44) ima veći energetski potencijal od
košaraste vrbe, a procesi kosagorevanja su ekonomski opravdani, ukoliko bi se koristili
manji procentualni odnosi (oko 10%) biomas
Electrocatalysis of hydrogen and oxygen electrode reactions in alkaline media by Rh-modified polycrystalline Ni electrode
No full textDeveloping novel electrocatalysts for energy conversion applications is of utmost importance for reaching the energy security of modern society. Here we present a comprehensive investigation of rhodium-modified polycrystalline nickel as an electrocatalyst for hydrogen and oxygen electrode reactions in alkaline media. The surface modification of nickel electrodes was achieved by facile galvanic displacement (up to 30 s) from a highly concentrated acidic Rh3+ solution. The results demonstrate a significant enhancement in the electrocatalytic activity for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) on the Rh-modified Ni electrodes, positioning galvanic displacement as a viable approach to engineering advanced electrocatalysts for clean energy applications. On the other hand, the hydrogen oxidation (HOR) and oxygen reduction reaction (ORR) activities of the Rh-modified electrodes are lower compared to polycrystalline platinum. It is suggested that semiconducting Rh2O3 has a detrimental role on the HOR and ORR performance, while the activities of HER and OER, dominantly taking place on metallic Rh and conductive RhO2, are very high. This research sheds light on the mechanisms underlying the enhanced electrode kinetics on Rh-modified Ni electrodes and provides insights into the development of efficient and cost-effective electrocatalysts for renewable energy technologie
Low-dose ionizing radiation generates a hormetic response to modify lipid metabolism in Chlorella sorokiniana
No full textAlgal biomass is a viable source of chemicals andmetabolites for various energy, nutritional, medicinal
and agricultural uses. While stresses have commonly been used to induce metabolite accumulation in
microalgae in attempts to enhance high-value product yields, this is often very detrimental to growth.
Therefore, understanding how to modify metabolism without deleterious consequences is highly
beneficial. We demonstrate that low-doses (1–5 Gy) of ionizing radiation in the X-ray range induces a
non-toxic, hormetic response in microalgae to promote metabolic activation. We identify specific
radiation exposure parameters that give reproducible metabolic responses in Chlorella sorokiniana
caused by transcriptional changes. This includes up-regulation of >30 lipid metabolismgenes, such as
genes encoding an acetyl-CoA carboxylase subunit, phosphatidic acid phosphatase,
lysophosphatidic acid acyltransferase, and diacylglycerol acyltransferase. The outcome is an
increased lipid yield in stationary phase cultures by 25% in just 24 hours, without any negative effects
on cell viability or biomass
Evolution of ferroelectric and piezoelectric properties of BiFeO3 ceramics doped with lanthanum and zirconium
No full textIn this study, we performed cation substitutions at Bi-site (La3+) and Fe-site (Zr4+) to investigate their possible benefit for the ferroelectric properties of BiFeO3 ceramics. The cations with higher valence (Zr4+) ought to suppress the formation of structural defects during syntheses, such as oxygen vacancies and Fe2+. These defects are responsible for high leakage currents and low breakdown voltages characteristic of the pure BiFeO3. However, doping only with Zr did not improve the ferroelectric properties of bismuth ferrite. These samples were unable to persist electric fields above 30 kV/cm. On the other hand, the increase in lanthanum concentration resulted in improved ferroelectric and piezoelectric properties of the samples, sustaining electric fields above 100 kV/cm. Among the investigated samples, the highest remnant polarization of 24 μC/cm2 and piezoelectric coefficient (d33) of 34 pC/N reached Bi0.85La0.15FeO3 sample at 160 kV/cm. The share of non-ferroelectric contribution to the total polarization of this sample was the lowest (∼ 11 %). When it comes to the co-doped samples, the addition of Zr transformed the behavior from leaky ferroelectric to predominantly leaky dielectric. It indicated that doping with La significantly improved the ferroelectric properties of bismuth ferrite ceramics. In contrast, even a low Zr concentration of 1 mol% could outbalance the influence of much larger La concentrations (10 and 15 mol%)
Encapsulated Thuja plicata essential oil into biopolymer matrix as a potential pesticide against Phytophthora root pathogens
No full textA new formulation that gradually released encapsulated Thuja plicata essential oil (TPEO) as an active component from a biopolymer matrix within a given period was obtained. Antimicrobial activity was determined in in-vitro tests where pure TPEO successfully inhibited the development of different Phytophthora species. The TPEO essential oil was encapsulated into the biopolymer matrix and an oil-in-water emulsion was formed. FTIR spectra analysis confirmed the formation of electrostatic interaction between these polymers, and hydrogen interactions between active components of TPEO and polymer chains. The stability of the emulsions was confirmed by zeta potential measurements, with a value of about 30 mV, even after 14 days of aging. UV‐Vis spectra analysis revealed that >60 % of TPEO remained in the emulsion after 14 days of exposure to ambient conditions, whereas pure TPEO evaporated faster, and around 20 % remained after 6 days. Encapsulated TPEO almost completely inhibited the growth of Phytophthora species during the ten-day day's exposition being statistically significantly improved compared to fungicide treatment. It was demonstrated that the emulsion exhibited a prolonged antimicrobial effect and successfully suppressed the growth of Phytophthora species, and can be considered as a means of protection in forests and crops
A novel lignin-based nanomaterial from silicon-doped dehydrogenated polymer of coniferyl alcohol
No full textIn this study, we proposed a novel approach to synthesize nanomaterial utilizing dehydrogenated polymer (DHP) derived from coniferyl alcohol (CA) with silicon doping. The synthesis of DHP involves enzymatic dehydrogenation of CA in a phosphate buffer using horseradish peroxidase (HRP) and hydrogen peroxide. This is followed by the hydrothermal synthesis of nanoparticles in the presence of ethylenediamine, which acts as a cross-linking agent and introduces amine groups in the final nanoparticle structure. Previous research has demonstrated that the introduction of silicon in the process of enzymatic polymerization significantly reduces the formation of large fractions of DHP and introduces Si-OH groups in the DHP structure [1]. We utilize silicon-doped DHP to improve the resulting nanoparticles' size, physicochemical properties, and performance. Our findings show that silicon significantly influences the structure and reduces the size of nanoparticles, as evidenced by a comparison of nanoparticles with and without incorporated silicon. The physicochemical properties and morphology of the synthesized nanoparticles are characterized using analytical techniques such as dynamic light scattering (DLS) and atomic force microscopy (AFM). As lignin-derived materials, these nanoparticles have the potential to act as antimicrobial agents. Considering that DHP demonstrated antibacterial activity [2], nanomaterials based on this polymer offers a promising path for the development of advanced materials for the pharmaceutical industry. Moreover, silicon-doped nanomaterials, mimicking lignin with improved characteristics due to silicon incorporation, hold significant promise for diverse applications such as drug carriers for targeted drug delivery or fabrication of biocides for agricultural production
Novel batavia lettuce cultivars-choosing the optimal cultivar for fresh and processed products using WASPAS method-Abstract
No full textSix Batavia lettuce cultivars ('Tourbillon', 'Champollion', 'Impression', 'Voltron', 'Bataille', and
'Batsun') were grown in the black marsh soil in March-May 2020. 'Tourbillon' is a standard
Batavia cultivar, while five others are not registered on the Variety list in Serbia. This study
aimed to select the optimal Batavia cultivar according to agronomic parameters, suitable for the
fresh market and processed products by applying the WASPAS (Weighted Aggregates Sum
Product Assessment) method. The correlation analysis was carried out to reduce the number of
criteria having high coefficient values above 0.8 to exclude double influence on the ranking
results. The study involved six alternatives (cultivars) and six different criteria regarding
agronomic parameters (rosette height, rosette fresh weight, number of leaves, stem diameter,
stem fresh weight, and core ratio). According to the expert’s opinion, we depicted morphological
traits of interest significant for fresh and processed lettuce products. Thus, according to the
selected criteria and both scenarios, the obtained results showed that cultivar A2-'Voltron' was
the best-ranked for fresh and processed products, while cultivar A3-'Champollion' showed the
least favorable results. A SAW (Simple Additive Weighting) method was applied to verify and
confirm the obtained results by the WASPAS method. Therefore, this study showed that the
WASPAS method could present an initial step toward decision-making in the selection of novel
lettuce cultivars for the fresh market and ready-to-eat salads and highlighted the importance of
choosing the adequate cultivar for different purposes to avoid quality and economic losses
Genome sequence data for 61 isolates of Xanthomonas campestris pv. campestris from Brassica crops in Serbia
No full textThis Technical Resource describes genome sequencing data for 61 isolates of the bacterial pathogen Xanthomonas campestris
pv. campestris collected from Brassica and Raphanus crops between 2010 and 2021 in Serbia. We present the raw
sequencing reads and annotated contig-level
genome assemblies and determine the races of ten isolates. The data can be
used to test hypotheses and phylogeographic analyses and inform the design of informative molecular markers for population
genetics studies. When combined with phenotypic data, they could be used to dissect relationships between genotypes
and phenotypes such as host range and virulence. Finally, these genome sequences expand our inventory of plasmids
known to reside in this pathogen