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Analysis of the photosynthetic activity and the antioxidant capacity was carried out on the perennial forage grasses: English ryegrass (Lolium perenne L.), Tetramis cultivar, tall fescue (Festuca arundinacea Schreb.) Albena cultivar, meadow fescue (Festuca pratensis Huds.) selected population, red fescue (Festuca rubra L.) ecotype Ravnogor and smooth brome (Bromus inermis Leyss.) Nika cultivar. The analysis was performed during the summer and autumn periods of growth and development. As a basic physiological process, photosynthesis is tightly related to the plant tolerance to different stressors. In addition, tolerance to the secondary exerted oxidative stress directly depends on the antioxidant content. The analysis of the antioxidant capacity was performed by the methods of ferric and molybdate reduction. Photosynthetic activity and the amount of photoprotection were determined by chlorophyll fluorescence methods. The results show about a twofold higher increase in photosynthetic activity of the light phase in F. arundinacea, F. pratensis and B. inermis in summer, which increased with about 20% in L. perenne, F. arundinacea, 25% in F. rubra and decreased with about 15% in B. inermis in autumn. However, the levels of photoinhibition were comparatively low, indicating an absence of stress in practice. The antioxidant capacity was five times higher in the smooth brome from the Nika cultivar, as compared with the other grasses. The tall fescue from the Albena cultivar had the highest photosynthetic activity, uninhibited during the measurements under the high, as well as the low temperatures.

The choice of nitrogen source in a cultivation medium can specifically affect the physiology and biochemistry of microalgae. To increase the production of low-cost valuable biomass, the preferred nitrogen form for each alga should be determined. The aim of our study was to analyze the effects of different nitrogen sources and cultivation times on the growth, biochemical composition and the activities of glutamine synthetase, glutamate synthase, glutamate dehydrogenase, malate dehydrogenase, aspartate aminotransferase and proteases of Chlorella vulgaris R-06/2. Media supplemented with urea or ammonium nitrate provided similarly (p>0.05) high growth rates for a short cultivation time (4 days). The two nitrogen compounds applied simultaneously ensured better biomass yield but for prolonged cultivation. In the exponential growth phase, ammonium nitrate stimulated (p

Cultivars suitable for organic production systems differ in many aspects from those adapted to a conventional one. The present study aimed to evaluate 23 white lupine genotypes for a range of traits: stability, biomass productivity and related parameters, tolerance to Fusarium oxysporum, and nutritional forage value. The goal was to identify white lupine genotypes suitable for organic production conditions in Central Northern Bulgaria. Among the genotypes, Solnechnii, Termis Mestnii, and Tel Keram exhibited the highest dry mass productivity, surpassing 14 t/ha. Solnechnii and Termis Mestnii showed no symptoms of F. oxysporum infection but were unstable in terms of forage yield. On the other hand, the genotypes Bezimenii 1, Barde, 17 Nahrquell, and WAT showed a satisfactory level of stability. Ranking according to basic parameters of biochemical composition, energy, and protein nutritional value determined ranks 1 and 2 for Pink Mutant and Kijewskij Mutant. A genotype with a good balance and complex suitability for organic conditions, considering stability, productivity, and tolerance to F. oxysporum, was identified as Bezimenii 1. This genotype exhibited both stability and productivity while demonstrating high resistance to F. oxysporum (infestation index of 7.18%). [ABSTRACT FROM AUTHOR]

The present study compared the stress response of two microalgal strains - Arthronema africanum (Cyanoprokaryota) and Coelastrella sp. BGV (Chlorophyta), after heavy metals' treatment. Changes of algal growth, pigment and protein content were analyzed after adding Cu, Cd and Pb (50 µM and 100 µM) to the nutrition medium. It was found that Cd and Pb significantly inhibited growth and protein biosynthesis of microalgae, but the effect of Cu remained less pronounced. In both strains, a decrease of chlorophyll content was observed, while carotenoid content markedly increased, especially in Coelastrella sp. BGV biomass. The addition of 100 µM Cd and 100 µM Pb to the medium caused a strong enhancement of malondialdehyde in both microalgal strains, which corresponded to the significant increase of superoxide dismutase and catalase activity. The antioxidant enzymes appeared to be differently altered by heavy metals' exposure. The activity of SOD in the Arthronema africanum cells was most strongly affected by Cd, in contrast to Coelastrella sp. BGV that was highly increased by 100 µM Pb. The application of 100 µM Cd and 100 µM Pb increased in a similar manner catalase activity in both microalgae. The strains that were studied showed a high absorption capacity for metal ions, especially for Pb, which was absorbed largely than Cd and Cu. For that reason, we assumed that both microalga and, in particular, Coelastrella sp. BGV, could be successfully used for treatment of contaminated water bodies. [ABSTRACT FROM AUTHOR]

This study utilized a renewable energy source, agricultural waste, in anaerobic digestion (AD) at appropriate conditions to obtain biogas and biomethane as an energy carrier. Maize stalks underwent ultrasound (US) pre-treatment for better accessibility for microorganisms, as lignocelluloses have a stable structure, insoluble in water and resist both mechanical and enzymatic attack. The digestate after an anaerobic digestion process was used for cultivation of algae after adsorption with activated carbon for clarification. Photosynthetic microalgae have industrial and economic perspectives, so their low-cost cultivation has a great potential for many applications. The results showed the impact of US pre-treatment of maize stalks as a sole substrate and co-digested with algal biomass. The total yields were 1116 cm3/L, 1350.5 cm3/L and 1293.25 cm3/L for the untreated, ultrasonically pre-treated and microwaved maize stalks. The possibility of accumulating algal biomass using anaerobic digestate as a medium was demonstrated. US pre-treatment (400 W) showed high efficiency with respect to the extractives obtained per unit of energy input. Addition of 4 g/L of microalgal biomass as a co-substrate led to an increase in the biogas yield compared to native stalks. A small closed circle system, starting from anaerobic digestion of lignocellulosic substrates followed by microalgae cultivation in the digestate and subsequent return of microalgal biomass back in the bioreactor as a co-substrate was realized, encouraging circular economy. The suggested scheme is a simple and low-cost technology, as the substrate used is freely available and renewable, and algae proved to grow in a waste effluent as medium. [ABSTRACT FROM AUTHOR]

Taking into account the rising trend of the incidence of cancers of various organs, effective therapies are urgently needed to control human malignancies. However, almost all chemotherapy drugs currently on the market cause serious side effects. Fortunately, several studies have shown that some non‐toxic biological macromolecules, including algal polysaccharides, possess anti‐cancer activities or can increase the efficacy of conventional chemotherapy drugs. Polysaccharides are characteristic secondary metabolites of many algae. The efficacy of polysaccharides on the normal and cancer cells is not well investigated, but our investigations proved a cell specific effect of a newly isolated extracellular polysaccharide from the red microalga Porphyridium sordidum. The investigated substance was composed of xylose:glucose and galactose:manose:rhamnose in a molar ratio of 1:0.52:0.44:0.31. Reversible electroporation has been exploited to increase the transport through the plasma membrane into the tested breast cancer tumor cells MCF‐7 and MDA‐MB231. Application of 75 µg/mL polysaccharide in combination with 200 V/cm electroporation induced 40% decrease in viability of MDA‐MB231 cells and changes in cell morphology while control cells (MCF10A) remained with normal morphology and kept vitality. [ABSTRACT FROM AUTHOR]

The red microalga Porphyridium cruentum, a potential source of bioactive substances, was the subject of a study on the effect of nutrients and different CO2 concentrations (0.04 and 2%) on the growth, biochemical composition and synthesis of phycobiliproteins and polysaccharides. For this purpose the alga was grown on two nutrition media, referred in this manuscript as M1 and M2 (M1 is richer in chloride and nitrogen substances). We have estimated that the abovementioned parameters varied under different cultivation conditions. Best yield was observed in M1 in the presence of 2% CO2, with a peak of the measured biomass equal to 4.0±0.1 g L-1. On the other side, compared to M1, M2 stimulated the pigment synthesis when the culture was enriched with 2% CO2. The highest amount of carbohydrates and pigments was observed when the alga was grown with 0.04% CO2. These results confirm that Porphyridium cruentum posesses great adaptive capabilities that can be used in future biotechnological practices. [ABSTRACT FROM AUTHOR]

Mycorrhizal fungi, algae and cyanobacteria are some of the most important soil microorganisms and major components of a sustainable soil-plant system. This study presents for the first time evidence of the impact of green alga and cyanobacterium solely and in combination with arbuscular mycorrhizal fungi (AMF) on plant-antioxidant capacity. In order to provide a better understanding of the impact of AMF and soil microalgae on Ocimum basilicum L. performance, changes in the pattern and activity of the main antioxidant enzymes (AOEs), esterases and non-enzymatic antioxidants including phenols, flavonoids, ascorbate, and α-tocopherols were evaluated. The targeted inoculation of O. basilicum with AMF or algae (alone and in combination) enhanced the antioxidant capacity of the plants and the degree of stimulation varied depending on the treatment. Plants in symbiosis with AMF exhibited the highest antioxidant potential as was indicated by the enhanced functions of all studied leaf AOEs: 1.5-, 2- and more than 10-fold rises of superoxide dismutase (SOD), glutathione-S-transferase (GST) and glutathione reductase (GR), respectively. The greatest increase in the total esterase activity and concentration of phenols, flavonoids and ascorbate was marked in the plants with simultaneous inoculation of mycorrhizal fungi and the green algae. 2,2-diphenyl-1-pycril-hydrazyl (DPPH) free radical scavenging method and ferric reducing antioxidant power (FRAP) assay proved the increased plant antioxidant capacity after co-colonization of green algae and mycorrhizae. [ABSTRACT FROM AUTHOR]

We studied the impact of drought on growth regulation in leaves of 13 maize varieties with different drought sensitivity and geographic origins (Western Europe, Egypt, South Africa) and the inbred line B73. Combining kinematic analysis of the maize leaf growth zone with biochemical measurements at a high spatial resolution allowed us to examine the correlation between the regulation of the cellular processes cell division and elongation, and the molecular redox-regulation in response to drought. Moreover, we demonstrated differences in the response of the maize lines to mild and severe levels of water deficit. Kinematic analysis indicated that drought tolerant lines experienced less impact on leaf elongation rate due to a smaller reduction of cell production, which, in turn, was due to a smaller decrease of meristem size and number of cells in the leaf meristem. Clear differences in growth responses between the groups of lines with different geographic origin were observed in response to drought. The difference in drought tolerance between the Egyptian hybrids was significantly larger than between the European and South-African hybrids. Through biochemical analyses, we investigated whether antioxidant activity in the growth zone, contributes to the drought sensitivity differences. We used a hierarchical clustering to visualize the patterns of lipid peroxidation, H2O2 and antioxidant concentrations, and enzyme activities throughout the growth zone, in response to stress. The results showed that the lines with different geographic region used different molecular strategies to cope with the stress, with the Egyptian hybrids responding more at the metabolite level and African and the European hybrids at the enzyme level. However, drought tolerance correlated with both, higher antioxidant levels throughout the growth zone and higher activities of the redox-regulating enzymes CAT, POX, APX, and GR specifically in leaf meristems. These findings provide evidence for a link between antioxidant regulation in the leaf meristem, cell division, and drought tolerance. [ABSTRACT FROM AUTHOR]

The influence of different nitrogen sources (ammonium nitrate, urea and ammonium nitrate + urea) and different concentration of the medium, containing both nitrogen sources on the growth and the content of pigment, protein, carbohydrate and lipid of a newly isolated green alga Scenedesmus sp. BGP was studied. Even though the two nitrogen sources were present in the medium routinely used in the lab, the experiments showed that the use of medium with each one of them separately gave a better yield of algal biomass for the whole cultivation period. The best growth was observed in urea-containing medium, where the dry weight reached 9.0 g/l. Dilution of the standard medium (2-, 4- and 8-fold) had positive impact on the growth, in contrast to 2-fold concentrated. The total amount of pigments (chlorophyll a+b and carotenoids) correlated with the change of growth in the different media. As a whole, carbohydrates, followed by proteins and lipids, dominated the biochemical composition of Scenedesmus sp. BGP. The biomass of the alga, grown in urea- or ammonium nitrate-containing medium was characterized by stable qualitative content over the entire period of cultivation (about 29% proteins, 41% carbohydrates and 24% lipids). These results showed that the medium with urea was most suitable for cultivation of Scenedesmus sp. BGP, because as a nitrogen source, urea is more efficient in terms of productivity and is less expensive. [ABSTRACT FROM AUTHOR]

In this study, the contribution of nonenzymatic (ascorbate, glutathione) and enzymatic antioxidants (superoxide dismutase, catalase, glutathione reductase, glutathione S-transferase) in the first hours of recovery of the resurrection plant Haberlea rhodopensis from drought- and freezing-induced desiccation was assessed. The initial stage of recovery after desiccation is critical for plants, but less investigated. To better understand the alterations in the activity of antioxidant enzymes, their isoenzyme patterns were determined. Our results showed that ascorbate content remained high during the first 9 h of rehydration of desiccated plants and declined when the leaves′ water content significantly increased. The glutathione content remained high at the first hour of rehydration and then strongly decreased. The changes in ascorbate and glutathione content during recovery from drought- and freezing-induced desiccation showed great similarity. At the beginning of rehydration (1–5 h), the activities of antioxidant enzymes were significantly increased or remained as in dry plants. During 7–24 h of rehydration, certain differences in the enzymatic responses between the two plant groups were registered. The maintenance of a high antioxidant activity and upregulation of individual enzyme isoforms indicated their essential role in protecting plants from oxidative damage during the onset of recovery. [ABSTRACT FROM AUTHOR]

Isolation and characterization of new biologically active substances affecting cancer cells is an important issue of fundamental research in biomedicine. Trehalose lipid was isolated from Rhodococcus wratislaviensis strain and purified by liquid chromatography. The effect of trehalose lipid on cell viability and migration, together with colony forming assays, were performed on two breast cancer (MCF7—low metastatic; MDA-MB231—high metastatic) and one "normal" (MCF10A) cell lines. Molecular modeling that details the structure of the neutral and anionic form (more stable at physiological pH) of the tetraester was carried out. The tentative sizes of the hydrophilic (7.5 Å) and hydrophobic (12.5 Å) portions of the molecule were also determined. Thus, the used trehalose lipid is supposed to interact as a single molecule. The changes in morphology, adhesion, viability, migration, and the possibility of forming colonies in cancer cell lines induced after treatment with trehalose lipid were found to be dose and time dependent. Based on the theoretical calculations, a possible mechanism of action and membrane asymmetry between outer and inner monolayers of the bilayer resulting in endosome formation were suggested. Initial data suggest a mechanism of antitumor activity of the purified trehalose lipid and its potential for biomedical application. [ABSTRACT FROM AUTHOR]