The Experts below are selected from a list of 222 Experts worldwide ranked by ideXlab platform
Narumon W Harvey - One of the best experts on this subject based on the ideXlab platform.
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removal of lead pb2 by the cyanobacterium Gloeocapsa sp
Bioresource Technology, 2008Co-Authors: Suneerat Raungsomboon, Amnat Chidthaisong, Boosya Bunnag, Duangrat Inthorn, Narumon W HarveyAbstract:Abstract Pb 2+ removal ability of the viable-freshwater cyanobacterium Gloeocapsa sp. was studied in batch experiments. Gloeocapsa sp. was cultured in the Medium 18 with pH adjusted to 3, 4, 5, 6 and 7. Growth was subsequently determined based on the increase of chlorophyll-a content. Gloeocapsa sp. was able to grow at all pH levels tested, except at pH 3. Removal of Pb 2+ was then further studied under pH 4. The results showed that Pb 2+ concentration in the range of 0–20 mg L −1 was not inhibitory to Gloeocapsa sp. growth but reduced its Pb 2+ removal efficiency (by 4.5% when Pb 2+ concentration increased from 2.5 to 20 mg L −1 ). Pb 2+ removal characteristics followed the Langmuir adsorption isotherm with the maximum removal capacity ( q max ) of 232.56 mg g −1 . Adsorption of Pb 2+ by this cyanobacterium followed the second order rate reaction and intraparticle diffusion was likely the rate-determining step. The initial rate of Pb 2+ adsorption during intraparticle diffusion was slower under light than under dark conditions, indicating that light probably slowed down the initial rate of intraparticle diffusion through the repulsion effects on cell membrane.
Stephanie Balor - One of the best experts on this subject based on the ideXlab platform.
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Experimental modeling of calcium carbonate precipitation by cyanobacterium Gloeocapsa sp.
Chemical Geology, 2020Co-Authors: Irina Bundeleva, L S Shirokova, Oleg S Pokrovsky, Pascale Benezeth, Benedicte Menez, Emmanuelle Gerard, Stephanie BalorAbstract:17 pagesInternational audienceThe impact of cyanobacteria Gloeocapsa sp. on calcium carbonate precipitation has been examined by combining physico-chemical macroscopic and in-situ microscopic techniques. For this, Ca adsorption and assimilation and kinetic experiments were used to assess the existence of the metabolic process responsible for CaCO3 mineralization by Gloeocapsa sp. Experimental products were characterized by Scanning and Transmission Electron Microscopy (SEM and TEM) imaging, XRD analyses, coupled with Confocal Laser Scanning Microscopy (CLSM) and Raman micro-spectroscopy. Ca carbonate precipitation experiments were performed at an initial pH of 7.8 to 9.4 and 25 °C in supersaturated solutions (Ωcalcite = 1.5 to 150) in the presence of active cyanobacterial cells. During cyanobacterial photosynthesis, the solution pH increased up to 9.5-10.8 after the first 5-10 days of growth, the Ca concentration decreased and the supersaturation index attained a maximum followed by a gradual decrease due to progressive CaCO3 precipitation. Ca adsorption at the surface of live and inactivated Gloeocapsa sp. cells and Ca intracellular assimilation during cell growth were measured as a function of pH and Ca concentration in solution. The contribution of surface adsorption and intracellular uptake to total Ca removal from solution due to biocalcification does not exceed 10%. The presence of calcium carbonate, identified as calcite using Raman spectroscopy, on active Gloeocapsa sp. surfaces and in the vicinity of bacterial cell surfaces was evidenced using SEM. TEM and CLSM demonstrated cyanobacterial cell encrustation by CaCO3 precipitated in the form of nano-spheres adjacent to the cell surface. In contrast to other previously investigated calcifying bacteria, no cellular protection mechanism against Ca2 + adsorption and subsequent carbonate precipitation has been demonstrated for Gloeocapsa sp. This is most likely linked to the specific cellular organization of this species, which involves several cells in one single capsule. As such, planktonic cultures of Gloeocapsa sp. exhibit significant calcifying potential, making them important CO2-fixing microorganisms for both paleo-environmental reconstructions and technological applications
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experimental modeling of calcium carbonate precipitation by cyanobacterium Gloeocapsa sp
Chemical Geology, 2014Co-Authors: Irina Bundeleva, L S Shirokova, Oleg S Pokrovsky, Pascale Benezeth, Benedicte Menez, Emmanuelle Gerard, Stephanie BalorAbstract:The impact of cyanobacteria Gloeocapsa sp. on calcium carbonate precipitation has been examined by combining physico-chemical macroscopic and in-situ microscopic techniques. For this, Ca adsorption and assimilation and kinetic experiments were used to assess the existence of the metabolic process responsible for CaCO3 mineralization by Gloeocapsa sp. Experimental products were characterized by Scanning and Transmission Electron Microscopy (SEM and TEM) imaging, XRD analyses, coupled with Confocal Laser Scanning Microscopy (CLSM) and Raman micro-spectroscopy. Ca carbonate precipitation experiments were performed at an initial pH of 7.8 to 9.4 and 25 °C in supersaturated solutions (Ωcalcite = 1.5 to 150) in the presence of active cyanobacterial cells. During cyanobacterial photosynthesis, the solution pH increased up to 9.5-10.8 after the first 5-10 days of growth, the Ca concentration decreased and the supersaturation index attained a maximum followed by a gradual decrease due to progressive CaCO3 precipitation. Ca adsorption at the surface of live and inactivated Gloeocapsa sp. cells and Ca intracellular assimilation during cell growth were measured as a function of pH and Ca concentration in solution. The contribution of surface adsorption and intracellular uptake to total Ca removal from solution due to biocalcification does not exceed 10%. The presence of calcium carbonate, identified as calcite using Raman spectroscopy, on active Gloeocapsa sp. surfaces and in the vicinity of bacterial cell surfaces was evidenced using SEM. TEM and CLSM demonstrated cyanobacterial cell encrustation by CaCO3 precipitated in the form of nano-spheres adjacent to the cell surface. In contrast to other previously investigated calcifying bacteria, no cellular protection mechanism against Ca2 + adsorption and subsequent carbonate precipitation has been demonstrated for Gloeocapsa sp. This is most likely linked to the specific cellular organization of this species, which involves several cells in one single capsule. As such, planktonic cultures of Gloeocapsa sp. exhibit significant calcifying potential, making them important CO2-fixing microorganisms for both paleo-environmental reconstructions and technological applications.
Aran Incharoensakdi - One of the best experts on this subject based on the ideXlab platform.
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uv radiation induced biosynthesis stability and antioxidant activity of mycosporine like amino acids maas in a unicellular cyanobacterium Gloeocapsa sp cu2556
Journal of Photochemistry and Photobiology B-biology, 2014Co-Authors: Rajesh P Rastogi, Aran IncharoensakdiAbstract:Abstract The biosynthesis of natural sunscreening compounds as influenced by ultraviolet radiation, their stability and antioxidant activity were studied in the cyanobacterium Gloeocapsa sp. CU-2556. An analysis by high-performance liquid chromatography (HPLC) with photodiode-array (PDA) detection revealed the biosynthesis of two MAAs, shinorine (UVλmax 333 nm) and an unknown MAA designated as M-307 (UVλmax 307 nm) with retention times of 5.9 and 6.4 min, respectively. Induction of the synthesis of MAAs was studied under 395 (PAR), 320 (PAR + UV-A) and 295 (PAR + UV-A + UV-B) nm cut-off filters. MAAs induction was significantly increased with an increase in exposure time up to 72 h in the samples covered with 295 nm cut-off filters. Contrary to shinorine, the biosynthesis of M-307 was more dominant in this unicellular cyanobacterium. Both MAAs were highly stable to some physico-chemical stressors such as UV radiation, heat and a strong oxidizing agent. The MAA M-307 was more stable under strong oxidative stress than shinorine. Moreover, UV-C radiation drastically decreased the stability of both MAAs. The MAAs (shinorine + M-307) also exhibited efficient antioxidant activity which was dose-dependent. The results indicate that MAAs may perform a vital role in survival and sustainability of Gloeocapsa sp. CU-2556 in harsh environmental conditions by its ability to absorb/screen short wavelength UV radiation and antioxidant function.
Hristo Najdenski - One of the best experts on this subject based on the ideXlab platform.
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Antibacterial and antifungal activities of selected microalgae and cyanobacteria
International Journal of Food Science and Technology, 2013Co-Authors: Hristo Najdenski, Liliana Gigova, Ivan Iliev, P. Pilarski, Jaromir Lukavský, Iva Tsvetkova, Mariana Ninova, Vesselin KussovskiAbstract:Summary In vitro activity of nine cyanobacterial and ten microalgal newly isolated or culture collection strains against eight significant food-borne pathogens has been evaluated and compared. Water extracts and culture liquids of Gloeocapsa sp. and Synechocystis sp. demonstrated the widest spectrum of activity with minimal inhibitory concentration (MIC) ranging from 1.56 to 12.5 mg mL−1. Culture liquid of Anabaena sp. had the highest activity (MIC = 0.39 mg mL−1) but only to Gram-positive bacteria. Ethanol extracts and fatty acids from all cyanobacteria and microalgae were active against Streptococcus pyogenes and/or Staphylococcus aureus. The fatty acids of Synechocystis sp. inhibited the growth of Bacillus cereus, Escherichia coli and Candida albicans (MIC values of 2.5–1.25 mg mL−1, respectively). Exopolysaccharides (EPS) of Gloeocapsa sp. were the sample that exhibited activity against all test pathogens with lowest MIC values (0.125–1 mg mL−1). High activity with a narrower range of susceptible targets demonstrated the exopolysaccharides of Synechocystis sp. and Rhodella reticulata. Antimicrobial activity was proven for phycobiliproteins isolated from Synechocystis sp., Arthrospira fusiformis, Porphyridium aerugineum and Porphyridium cruentum, respectively. In conclusion Gloeocapsa sp. and Synechocystis sp. and especially their exopolysaccharides showed the most promising potential against the examined food pathogens.
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suboptimal growth temperatures enhance the biological activity of cultured cyanobacterium Gloeocapsa sp
Journal of Applied Phycology, 2013Co-Authors: G. Gacheva, Liliana Gigova, Reneta Toshkova, Elena Gardeva, Natalia Ivanova, Ivan Iliev, Vesselin Kussovski, Hristo NajdenskiAbstract:The cytotoxic, antibacterial, and antifungal activities of cyanobacterium Gloeocapsa sp. strain Gacheva 2007/R-06/1 were investigated and the possibility for an enhancement of these activities by changing the culture conditions evaluated. Fatty acids of this cyanobacterium were found to be active against Streptococcus pyogenes. Exopolysaccharides inhibited the growth of both Gram-positive and Gram-negative bacteria and the fungus Candida albicans. Both exopolysaccharides and fatty acid mixtures also significantly decreased the viability of human cervical carcinoma cells, HeLa. Greater biological activities were exhibited by Gloeocapsa sp., cultured at suboptimal temperatures (15–26°C) than at optimal and supraoptimal ones. In comparison with higher light intensity, the low-light cultivation stimulated the cytotoxicity of the fatty acids. In general, low temperatures decreased the growth of Gloeocapsa sp., but promoted its biological activity. Prolonged cultivation also had a beneficial impact on the bioactivity. Compared to 4 days, the 17-day cultivation resulted in fourfold higher antibacterial and antifungal activities of exopolysaccharides and more than twice increases in their cytotoxicity. The study revealed that this cyanobacterial isolate is a new source of natural products with potential for pharmacological and medical applications.
G. Gacheva - One of the best experts on this subject based on the ideXlab platform.
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growth biochemical and enzymatic responses of thermal cyanobacterium Gloeocapsa sp cyanophyceae to temperature and irradiance
Phycological Research, 2013Co-Authors: G. Gacheva, Liliana Gigova, Natalia Ivanova, P. Pilarski, Jaromir LukavskýAbstract:Summary The present study describes a strain of Gloeocapsa sp. designated as Gacheva 2007/R-06/1, originally isolated from a geothermal flow located in Rupite, Bulgaria. To evaluate whether this cyanobacterium is locally adapted to hot environment or has the ability to tolerate lower temperatures, its growth, biochemical composition, enzyme isoforms and activity of the main antioxidant enzymes and proteases were characterized under various temperatures and two irradiance levels. The strain was able to grow over the whole temperature range (15–40°C) under two different photon fluence densities – 132 μmol photons m−2 s−1 (unilateral, low light, LL) and 2 × 132 μmol photons m−2 s−1 (bilateral, high light, HL). The best growth occurred at either 34°C and LL or at 36°C and HL, but significant growth inhibition was noted at 15°C and 40°C. Low temperature treatment (15°C) resulted in higher levels of total protein and an increased activity of manganese superoxide dismutase (MnSOD) and glutathione reductase, as compared to optimum growth temperatures. After simultaneous exposure to 15°C and HL, increases in lipid content and activity of iron superoxide dismutase and catalase (CAT) were also observed. Cultivation of cells at 40°C enhanced MnSOD, CAT and peroxidase activities, regardless of irradiance level. Increased total protein content and protease activity at 40°C was only associated with the HL treatment. Overall, these results indicate that Gloeocapsa sp. strain Gacheva 2007/R-06/1 used different strategies to enable cells to efficiently acclimate and withstand adverse low or high temperatures. This strain obviously tolerates a wide range of temperatures below its natural habitat temperature, and does not seem to be locally adapted to its original thermal regime. It behaved as a thermotolerant rather than a thermophilic cyanobacterium, which suggests its wider distribution in nature.
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suboptimal growth temperatures enhance the biological activity of cultured cyanobacterium Gloeocapsa sp
Journal of Applied Phycology, 2013Co-Authors: G. Gacheva, Liliana Gigova, Reneta Toshkova, Elena Gardeva, Natalia Ivanova, Ivan Iliev, Vesselin Kussovski, Hristo NajdenskiAbstract:The cytotoxic, antibacterial, and antifungal activities of cyanobacterium Gloeocapsa sp. strain Gacheva 2007/R-06/1 were investigated and the possibility for an enhancement of these activities by changing the culture conditions evaluated. Fatty acids of this cyanobacterium were found to be active against Streptococcus pyogenes. Exopolysaccharides inhibited the growth of both Gram-positive and Gram-negative bacteria and the fungus Candida albicans. Both exopolysaccharides and fatty acid mixtures also significantly decreased the viability of human cervical carcinoma cells, HeLa. Greater biological activities were exhibited by Gloeocapsa sp., cultured at suboptimal temperatures (15–26°C) than at optimal and supraoptimal ones. In comparison with higher light intensity, the low-light cultivation stimulated the cytotoxicity of the fatty acids. In general, low temperatures decreased the growth of Gloeocapsa sp., but promoted its biological activity. Prolonged cultivation also had a beneficial impact on the bioactivity. Compared to 4 days, the 17-day cultivation resulted in fourfold higher antibacterial and antifungal activities of exopolysaccharides and more than twice increases in their cytotoxicity. The study revealed that this cyanobacterial isolate is a new source of natural products with potential for pharmacological and medical applications.
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Growth inhibitory activity of selected microalgae and cyanobacteria towards human cervical carcinoma cells (HeLa)
2011Co-Authors: Liliana Gigova, Reneta Toshkova, Elena Gardeva, G. Gacheva, Natalia J. Ivanova, Liliya Yossifova, Georgi D. PetkovAbstract:Although a large number of strains have been shown to possess anticancer activity, the microalgal and cyanobacterial potential is still largely unexplored. The present study was aimed to evaluate and compare the growth inhibitory activity of 33 extracts, 15 fatty acid mixtures and five exopolysaccharides from 19 species on HeLa cells, using MTT assay. All investigated strains showed growth inhibitory activity of at least one tested extract/constituent. More than 80% decrease in Hela cells viability was registered for the crude hot water extract of Gloeocapsa sp. and ethanol extracts of the new Bulgarian isolates Gloeocapsa sp. and Chlorella sp. Most active cell-free culture liquids were these of Anabaena sp. and Synechocystis sp., while the exopolysaccharides of Gloeocapsa sp. exhibited the lowest IC 50 value (24.4 µg/ml). An interesting and useful finding of our investigation was that the isolated fatty acid mixtures from five out of eight cyanobacterial strains and from four out of seven microalgal strains studied had potent activity against HeLa tumor cells with the IC 50 values under 30 µg/ml and even under 15 µg/ml. High percentage of the active Bulgarian isolates among the strains tested fulfil the effort of screening cyanobacteria and microalgae of local habitats. In conclusion, the most promising strains for further study are the thermal cyanobacteria Synechocystis sp. and especially Gloeocapsa sp., which showed the strongest inhibition of tumor cell growth and produced wider range of active components.