3828 research outputs found
Sort by
Aktivacija antioksidativnog metabolizma micelije Phycomyces blakesleeanus u različitim fazama rasta
No full textUnderstanding the effect of vanadate (V(V)) on the well-studied filamentous fungus, Phycomyces blakesleeanus, is of great importance for establishing the mechanisms of vanadium internalisation and metabolism. Although P. blakesleeanus is not a soil fungus, its short life cycle and evolutionary basal position in the fungal kingdom makes it an excellent model for studying the interactions of fungi with vanadate and other metals as well as the improvement of their use in vanadium recovery (bioaccumulation) and the remediation of contaminated soils. In this study, we investigated the effects of vanadate at three concentrations (1 mM, 5 mM, and 10 mM) on both enzymatic and non-enzymatic components of the antioxidant system of mycelia at different growth stages. The production of ROS was highest in the exponential phase, but its reducing capacity was maintained, probably due to high levels of non-enzymatic antioxidants such as phenols and glutathione. In the stationary phase, while the reducing capacity of the mycelia was somewhat impaired by vanadate (V(V)), it recovered due to the action of the glutathione system and the activation of peroxidases. In the late exponential/early stationary phase, no significant activation of the antioxidative systems was observed, and the reducing capacity was impaired. When we consider the effects of V(V) on mycelial growth, this was the only phase with reduced viability, while the exponential and stationary phases were unaffected, if not stimulated. This study provides insight into the tolerance of P. blakesleeanus mycelia to vanadate, even at concentrations as high as 10 mM, making this fungus a good candidate for V(V) bioaccumulation.Razumevanje efekta vanadata (V(V)) na dobro istraženoj filamentoznoj gljivi, Phycomy-ces blakesleeanus, značajno je za utvrđivanje mehanizama internalizacije i metabolizma vanadijuma. Iako P. blakesleeanus nije zemljišna gljiva, njen kratak životni ciklus i evolu-ciona pozicija u bazi carstva gljiva čine je odličnim modelom za proučavanje interakcija gljiva sa vanadatom i drugim metalima, što može dovesti do poboljšanja primene gljiva u bioakumulaciji vanadijuma i remedijaciji kontaminiranih zemljišta. U ovom istraživanju smo proučavali efekte tri koncentracije vanadata (1 mM, 5 mM i 10 mM) na enzimske i neenzimske komponente antioksidativnog sistema micelije u različitim fazama rasta. Proizvodnja ROS (reaktivnih kiseoničnih vrsta) bila je najviša u eksponencijalnoj fazi, ali je redukujući kapacitet održan zahvaljujući visokom nivou neenzimskih antioksidanata kao što su fenoli i glutation. U stacionarnoj fazi, redukujući kapacitet micelije je donekle bio narušen prisustvom vanadata (V(V)), ali se oporavio zahvaljujući delovanju gluta-tionskog sistema i aktivaciji peroksidaza. U kasnoj eksponencijalnoj/ranoj stacionarnoj fazi nije primećena značajna aktivacija antioksidativnih sistema, i redukujući kapacitet je bio narušen. Kada uzmemo u obzir efekte V(V) na rast micelije, ovo je bila jedina faza sa smanjenom vitalnošću, dok je stopa rasta u eksponencijalnoj i stacionarnoj fazi bila nepromenjena, ako ne i povećana. Ovo istraživanje pruža uvid u toleranciju micelije P. blakesleeanus na vanadat, čak i pri visokim koncentracijama, do 10 mM, što čini ovu gl-jivu dobrim kandidatom za bioakumulaciju V(V)
Smart biofertilizers and bacterial community profiles: from maturation to impact in the field
No full textPlant-based compost mixtures have proven to be a sustainable solution for improving
plant growth and soil fertility. Our aim was to determine the dynamics of bacterial shifts
by amplicon sequencing during the composting process in a 14-day period, to identify
the bacteriobiota in the final product and to test the different formulations in the maize
cropping system. We analyzed the maturation of plant-based compost (T1), with the
addition of biochar after (T2) and during the composting process (T3). In addition, the
same formulations were coated with bacterial formulations (Priestia megaterium and
Glutamicibacter sp., T4-T6) and their effects on maize growth were investigated. T3
showed significant differences compared to T1 and T2. The T3 formulation was
dominated by the taxa Hymenobacter, Pedobacter, Pseudomonas, Rhizobiaceae,
Sphingobacterium and Sphingomonas only on the first day, while Dyadobacter and
Methylobacterium were abundant in T1. Differential analysis revealed that Bacillus,
Cellvibrio and Geobacillus as well as Ureibacillus, Thermobacillus,
Thermoactinomycetaceae and Pusillibacter were significantly more abundant only in
mature T3, while Acinetobacter, Isoptericola and Sphingobacterium were characteristic
of T1 and T2. T3 showed higher values for C/N ratio, P2O5 and K2O compared to the other
varieties. The field results showed that T3 and T6 produced the tallest maize plants, while
T5 and T6 had a higher grain weight. In terms of yield results, T8 was ahead, followed by
T2 and T6. The addition of biochar in combination with bacterial formulations resulted in
different bacterial communities and improved plant growth, underlining its potential as
an effective agricultural supplement.ISBN број није доступан
First assessment of environmental genotoxicity using the the long-fingered bat Myotis capaccinii (Bonaparte 1837) as a bioindicator
No full textCoal remains a major energy source around the world, although it contains radioactive elements, metals, and organic compounds that can adversely affect the DNA of exposed organisms [1]. Bats, with their widespread distribution, are frequently impacted by environmental pollution, taking in contaminants through their diet, water, skin, and even by inhalation. They act as sensitive bioindicators, making them valuable for assessing environmental quality [2]. One such species, the long-fingered bat Myotis capaccinii (Bonaparte 1837) is recognized as endangered in Europe and it is strictly protected by the Serbian legislation. The aim of this study was to investigate the genotoxic response in M. capaccinii blood cells using the alkaline comet assay. It also sought to identify variations in response related to the age groups and sex of the bats, as well as the sampling season. Additionally, follow-up analyses were conducted to measure the levels of 11 elements (As, Cd, Co, Cr, Cu, Fe, Li, Mn, Ni, Pb, and Zn) in the bats' hair. The sampling was conducted in two caves in eastern Serbia, Bogovinska Cave and Sesalačka Cave, natural monuments and protected natural resources of III category, both located near coal mining activities. In 2024 during summer and autumn, 24 bats were studied and categorized into groups based on sex (male/female), age (juveniles/adults), and season (summer/autumn). For the analysis of elemental concentration, a total of 24 hair samples were collected from the dorsal side of the specimens and subsequently transferred into vials for inductively coupled plasma optical emission spectrometry (ICP-OES) analysis. For the comet assay, 15 samples of capillary blood were obtained through a non-lethal technique from the intrafemoral vein and stored in 1 mL of cryopreservation medium in liquid nitrogen until analysis. The findings indicated that DNA damage was significantly higher in bats sampled during summer compared to their autumn counterparts. There were no statistically significant differences detected between sexes or age groups. A significant positive correlation was found between chromium concentrations and DNA damage, suggesting a potential link to environmental contamination, likely resulting from mining activities. Conversely, a significant negative correlation was observed between zinc concentrations and DNA damage, which may support its role as a protective agent against DNA damage and oxidative stress. This study is the first to utilize M. capaccinii as a bioindicator, and the results suggest that this species could be a useful indicator of the genotoxic potential in the environment
Isolation and characterization of Agrobacterium vacciniicorymbosi sp. nov. originating from crown galls in blueberry (Vaccinium corymbosum) in Serbia
No full textSeven bacterial isolates were obtained from crown gall in blueberry plants (Vaccinium corymbosum)
growing in Serbia in 2020. Phylogenetic analysis of the novel isolates using four housekeeping genes
– atpD, dnaK, glnA, and rpoB, as well as gene 16 S rRNA – revealed their distinct position, separate
from other known Agrobacterium species, but closest to A. vaccinii, A. rosae and A. rubi. Genome
sequencing of one of these blueberry isolates revealed less than 86% average nucleotide identity
(ANI) between the blueberry isolate and type strains of Agrobacterium species, indicating that it does
not belong to any previously described species. Although genome sequencing revealed absence of
the tumor-inducing (Ti) plasmid, stabbing the crown region with bacterial cultures induced gall-like
structures formed on blueberry plants (cultivar Duke). Phenotypically, these blueberry isolates were
differentiated from closely related Agrobacterium species in their utilization of dulcitol, d-tagatose and
xylitol. On the basis of these results, Serbian blueberry isolates are considered to represent a novel
species of the genus Agrobacterium, for which the name Agrobacterium vacciniicorymbosi sp. nov. is
proposed, with BA1120T (NCPPB 4800 = CFBP 9290) as the type strain. This isolate and BA2520 (NCPPB
4801 = CFBP 9291) have been deposited in public collections of plant pathogenic bacteria
IDENTIFICATION OF THE GENE POOL OF WOODY SPECIES IN ZVEZDARA FOREST – A FOUNDATION FOR GENETIC CONSERVATION AND BIODIVERSITY PROTECTION
No full textZvezdara Forest is part of Belgrade’s urban green system infrastructure within the
urban area. It covers approximately 137 ha, of which 80.57 ha are protected as a
IUCN Category III – Natural Monument or Feature. It was declared a protected area to
preserve the natural values, structure, and quality of the forest, soil, and air, as well
as to enhance a spatial unit shaped by human activity, which forms an important part
of the city's green space. The forest primarily contributes to preventing landslides,
regulating and improving microclimatic conditions, as well as providing space for
rest and recreation. The largest afforestation was done in the period 1948-1950,
as part of voluntary afforestation actions. It continued with large-scale planting,
and as a result Zvezdara was designated as a park-forest in the General Urban Plan
from 1972. In 2024, a reconnaissance of the terrain and recording of woody species
was conducted at 112 points, in order to identify the gene pool of woody species.
These points were previously projected within the borders of six compartments,
covering the area of forest management unit of park-forest entire area. A total of
90 woody species from 30 families (61 genera), were recorded. Among them, 16
species were highlighted as having particular conservation significance within the
forest resources of the Republic of Serbia. These include endemic species (Celtis
australis), relict species (Corylus colurna, Ostrya carpinifolia, Taxus baccata), rare
or threatened species (Acer campestre, Betula pendula, Fraxinus excelsior, Juglans
regia, Malus sylvestris, Prunus domestica, Ulmus laevis, U. glabra, U. minor), and
species at risk (Prunus avium, Pyrus pyraster, Sorbus torminalis). The gene pool of
these species is represented by individual trees and/or groups of trees, which were
georeferenced, mapped and measured for height, DBH and max crown spread.
Also, database was created as a basis for long-term monitoring, conservation and
sustainable use
Effect of ferric ions on the UV-induced degradation of piroxicam in acidic aqueous solution
No full textPiroxicam (PRX) is a nonsteroidal anti-inflammatory drug (NSAID) belonging to their oxicam class, widely recognized for its analgesic, antipyretic, and anti-inflammatory effects [1]. While PRX is effective in alleviating pain, inflammation, and stiffness associated with rheumatoid and osteoarthritis, its presence in environmental waters such as surface water, groundwater, drinking water, and effluents from wastewater treatment plants [2] become a growing ecological concern. Understanding the interactions between PRX and Fe³⁺ ions in aquatic environments is essential for developing effective removal strategies, particularly those based on advanced oxidation processes (AOPs) that can be initiated or enhanced by ultraviolet (UV) irradiation. In this study, the photodegradation of PRX in the presence of Fe³⁺ ions at pH 5 was investigated using UV-Vis spectroscopy and cyclic voltammetry (CV). Under acidic conditions, PRX is resistant to degradation by UVA and UVB irradiation. However, in the presence of Fe³⁺, the formed Fe³⁺-PRX complex becomes susceptible to oxidation by HO• radicals generated through UV-induced photolysis of Fe³⁺–OH⁻ complexes. These findings were confirmed by CV analysis, which implied that chelation with Fe³⁺ increases the oxidative susceptibility of PRX, as indicated by a shift in oxidation/anodic peak potentials to lower values. Finally, the toxicity of the photodegradation products was assessed using Artemia salina, providing insight into the potential ecological impact of the degradation process
Effect of beneficial bacteria on antioxidative and amino acid metabolic responses of cabbage plants infected with Xanthomonas campestris pv. campestris
No full textCabbage cv. Futoški is well recognized in Serbia as an autochthonous cultivar with exceptional
quality attributes and nutritional traits. The projected annual yield of cabbage is threatened by
the black rot disease caused by phytopathogenic bacterium Xanthomonas campestris pv.
campestris (Xcc). In an effort to suppress the disease in an ecologically friendly manner,
bacterial strains with antagonistic activity are being evaluated for their efficacy in disease
suppression. This study examined the response of cabbage plants to infection with Xcc and
preventive treatment with the indigenous Bacillus velezensis strain RD-FC 88. To fully
understand the plant–pathogen–biocontrol agent interaction, we analyzed changes in the plant’s
primary and antioxidative metabolism, focusing on antioxidative enzymes activity, redox status
of ascorbate and glutathione, and the soluble amino acid content. Results showed that the
activities of catalase (CAT) and polyphenol oxidase (PPO) were not significantly affected by
Xcc infection. However, peroxidase (POD) activity was reduced twofold in Xcc infected plants
compared to respective controls. The preventive application of the biocontrol strain to infected
plants did not modify the response compared to treatment with Xcc alone. Infection with Xcc
led to an increased concentration of reduced glutathione (GSH), while the level of reduced
ascorbate (AsA) was lowered compared to the corresponding controls. This could imply a
central role of GSH in maintaining redox homeostasis and the regeneration of ascorbate through
the ascorbate–glutathione cycle contributing to the overall plant’s antioxidative defense
metabolism. Additionally, Xcc infection resulted in a reduction in the levels of most free amino
acids, including those involved in the three biosynthetic pathways of glucosinolates. The most
significant decreases were observed in aliphatic amino acids such as alanine, valine and leucine,
but also in the content of aromatic acids e.g. tyrosine and tryptophan in the presence of the
pathogen Xcc. Notably, the application of the biocontrol strain restored the levels of nearly all
measured amino acids, with the most pronounced recovery observed in lysine and tryptophan
concentrations. Infection with Xcc modifies the components of the antioxidative and amino
acid metabolism in cabbage cv. Futoški. While application of Bacillus velezensis strain RD-FC
88 did not restore enzyme activity, it showed promising results in recovering amino acid levels,
highlighting its potential as a biocontrol agent. Understanding interactions between biocontrol
agents, pathogens, and host plants, particularly their effects on plant metabolism, is essential
for their effective and sustainable use in field conditions
Machine Learning Methods for Prediction of Wöhler Curves of Steel Ck 35
No full textThe fatigue behavior of materials is often analyzed using S-N (Wohler) curves that express the relationship between a stress level and the number of cycles to failure. This study is dealing with predictions of S-N behavior of quenched and tempered steel Cl 35 (DIN/EN) for different groups of specimens using three macine learning models: Support Vector Machine (SVM), Linear Regression (LR), and Gaussian Process Regression (GPR), implemented in the software package MATLAB. Using a material identifier extracted from sample codes, the dataset is partitioned into distinct groups. Available fatigue data for each group is alternatively split into training and test sets. The better fit the expected S-N curve relationship, both the stress (S) and cycle count (N) values are converted to a logarithmic scale. Each model is trained separately to predict fatigue life based on applied stress. Each model's predictive performance was evaluated using mean absolute percentage error. SVM and GPR models trained all groups and performed better than classical linear regression, particularly in nonlinear groups. Each group's predicted and experimental S-N curves were compared to assess accuracy. This approach indicates that there is a possibility of reducing the scope of experimental testing through the application of intelligent algorithms
Evaluation of Honey Authenticity and Quality Using HPLC‑PAD and Fluorescence with MCR‑ALS
No full textFake honey can negatively impact human health by introducing harmful
substances and affecting nutritional quality, making its detection
essential to prevent potential risks. This study investigates the sugar
profiles of pure honey samples and fake honey using High-Performance
Liquid Chromatography (HPLC) with a Pulsed Amperometric
Detection (PAD) method. The goal was to determine if spectrofluorimetry,
combined with multivariate analysis, could differentiate authentic
honey from honey adulterated with artificial sugars. In this study,
HPLC-PAD and spectrofluorimetry with Multivariate Curve Resolution-
Alternating Least Squares (MCR-ALS) were employed to distinguish genuine honey from counterfeit honey. The results from HPLC-PAD
analysis revealed the presence of monosaccharides Glucose (Glu),
Fructose (Fru), and Sucrose (Suc) in meadow honey, while the adulterated
honey contained only glucose. Spectrofluorimetric analysis identified
three emission components: at 350-360 nm (which corresponds
to proteins), 400 nm, and 440 nm (which corresponds to phenols) for
natural honey and fake honey. Fluorescence spectroscopy combined
with multivariate curve resolution–alternating least squares (MCR–
ALS) was used to determine the ratio of the spectral components
originating from phenol and proteins. Furthermore, the phenolic-toprotein
ratio in fake honey was significantly lower at 1.716, compared
to the ratio of 3.1967 found in authentic honey. These findings demonstrate
the potential of these methods in detecting honey adulteration
and ensuring the authenticity of honey products, contributing to
better public health safety
Catalase Activity in Honey Samples as an Indicator of Varroa destructor Infestation Levels in Honeybee Colonies
No full textVarroa destructor, a parasitic mite, represents a major threat to honeybee
colonies worldwide, causing significant colony losses and
reducing honey yield. The presence of Varroa mites disrupts the
health of the colony, leading to weakened bees and decreased productivity.
Honey is a highly nutritious food, containing substances
such as carbohydrates, amino acids, enzymes, and minerals in its
composition. In this study, we research the correlation between
enzyme activity in honey samples and the level of infestation in
honeybee hives. The catalase activity values obtained from honey
samples were averaged for samples originating from hives with
high, medium, and low levels of Varroa infestation. The R² value of
0.9988 indicates a strong linear correlation, and the results show a
significant increase in catalase enzyme activity in honey samples
from hives with high Varroa infestation compared to honey samples
from control hives. The observed increase in catalase activity
may be used as an indicator for assessing Varroa infestation levels
in beehives. These findings are consistent with the literature, which
suggests that changes in catalase activity can indicate oxidative
stress conditions in bee colonies