Nutrient deficiency induces a variety of cellular responses, including an increase in lipid accumulation in microalgae. Nitrogen starvation is the most studied deprivation. Here, we determine the effects of phosphorus and sulfur limitation on lipid accumulation in Chlorella vulgaris. A set of 9 experiments were performed, varying the initial concentration of these nutrients (set to 0, 50, and 100% of their original composition in Bold's basal medium). According to our results, the variation of P and S modified the specific growth rate, lag phase, and cell generation time. The ratio of 50%P and 0%S significantly increased the total lipid concentration. The fatty acid profile was dominated by C16:0, C18:0, and C18:1; a considerable increase in C20:5 was observed with 0%P and 50%S and 0%P and 100%S. Regarding neutral lipids, the response surface methodology (RSM) indicates that the maximum was observed when S was between 40 and 60% and P was between 95 and 100%. Therefore, the enhanced production of lipids caused by P and S limitation may contribute to the efficient oil production useful for algal biofuels.
Microalgae are the lowest plant organisms producing a wide range of metabolites that make them interesting organisms for industrial applications. Cultivation of green microalgal species Chlorella vulgaris resulted a significant production of extracellular polysaccharide (EPS). Preliminary chemico-spectroscopic studies on EPS revealed its molecular profile, a complex primary structure consisting of six monosaccharide units occurring in both furano and pyrano forms, a high sugar binding variability and the presence of partially methylated derivatives of some sugar constituents. Biological activity tests showed that EPS caused significant bronchodilatory, anti-inflammatory and antitussive effects in test animals. Chlorella EPS appears to be a promising agent for the prevention of chronic airway inflammation, which is the basic pathogenic mechanism of many respiratory diseases, including bronchial asthma.
- MeSH
- alergeny MeSH
- antiastmatika chemie metabolismus farmakologie MeSH
- bronchiální hyperreaktivita farmakoterapie imunologie patofyziologie MeSH
- chemické jevy MeSH
- Chlorella vulgaris metabolismus MeSH
- cytokiny metabolismus MeSH
- extracelulární prostor metabolismus MeSH
- hladké svalstvo účinky léků imunologie metabolismus MeSH
- mediátory zánětu metabolismus MeSH
- modely nemocí na zvířatech MeSH
- morčata MeSH
- polysacharidy biosyntéza chemie farmakologie MeSH
- spektrální analýza MeSH
- zvířata MeSH
- Check Tag
- morčata MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Quantification of selenated amino-acids currently relies on methods employing inductively coupled plasma mass spectrometry (ICP-MS). Although very accurate, these methods do not allow the simultaneous determination of standard amino-acids, hampering the comparison of the content of selenated versus non-selenated species such as methionine (Met) and selenomethionine (SeMet). This paper reports two approaches for the simultaneous quantification of Met and SeMet. In the first approach, standard enzymatic hydrolysis employing Protease XIV was applied for the preparation of samples. The second approach utilized methanesulfonic acid (MA) for the hydrolysis of samples, either in a reflux system or in a microwave oven, followed by derivatization with diethyl ethoxymethylenemalonate. The prepared samples were then analyzed by multiple reaction monitoring high performance liquid chromatography tandem mass spectrometry (MRM-HPLC-MS/MS). Both approaches provided platforms for the accurate determination of selenium/sulfur substitution rate in Met. Moreover the second approach also provided accurate simultaneous quantification of Met and SeMet with a low limit of detection, low limit of quantification and wide linearity range, comparable to the commonly used gas chromatography mass spectrometry (GC-MS) method or ICP-MS. The novel method was validated using certified reference material in conjunction with the GC-MS reference method.
- MeSH
- Chlorella vulgaris metabolismus MeSH
- limita detekce MeSH
- lineární modely MeSH
- malonáty MeSH
- methansulfonáty MeSH
- methionin analýza metabolismus MeSH
- pronasa MeSH
- reprodukovatelnost výsledků MeSH
- selenomethionin analýza metabolismus MeSH
- tandemová hmotnostní spektrometrie metody MeSH
- vysokoúčinná kapalinová chromatografie metody MeSH
- Publikační typ
- časopisecké články MeSH
Alkaline flocculation has been studied due to its potential as a low-cost harvesting method for microalgae. However, surface properties (zeta potential, contact angles) as inputs into physicochemical interaction models have not yet been applied systematically. In this work, forced alkaline flocculation of the freshwater microalgae Chlorella vulgaris induced by calcium phosphate precipitates was studied as a model system. Response surface methodology was used to quantify the effect of independent variables (concentration of Ca2+ (0.5-0.5 mM) and PO43- (0.05-0.35 mM), pH (8-12) and ionic strength (1-19 mM)) on the zeta potential (ZP) of microalgae, and the turbidity (T) of inorganic precipitates. Flocculation tests and their modified versions were carried out. The flocculation efficiencies obtained were interpreted with respect to predictions of physicochemical interaction models. It was found that flocculation was possible under conditions where appropriate precipitates were formed in the presence of cells. Under these conditions, flocculation of negatively charged Chlorella vulgaris was induced not only by positively charged, but also by negatively charged calcium phosphate precipitates at an early phase of nucleation. The driving force for interactions between oppositely charged cells and precipitate particles was electrostatic attraction, while the attraction between equally charged entities may have resulted from a negative total balance of apolar (Lifsitz-van der Waals) and polar (acid-base) interactions. Medium components did not interfere with flocculation, while cellular organic matter decreased flocculation efficiency only to a very limited extent.
Despite the extensive research, the mechanism of the antimicrobial and biocidal performance of silver nanoparticles has not been unequivocally elucidated yet. Our study was aimed at the investigation of the ability of silver nanoparticles to suppress the growth of three types of algae colonizing the wetted surfaces or submerged objects and the mechanism of their action. Silver nanoparticles exhibited a substantial toxicity towards Chlorococcales Scenedesmus quadricauda, Chlorella vulgaris, and filamentous algae Klebsormidium sp., which correlated with their particle size. The particles had very good stability against agglomeration even in the presence of multivalent cations. The concentration of silver ions in equilibrium with nanoparticles markedly depended on the particle size, achieving about 6 % and as low as about 0.1 % or even less for the particles 5 nm in size and for larger ones (40-70 nm), respectively. Even very limited proportion of small particles together with larger ones could substantially increase concentration of Ag ions in solution. The highest toxicity was found for the 5-nm-sized particles, being the smallest ones in this study. Their toxicity was even higher than that of silver ions at the same silver concentration. When compared as a function of the Ag(+) concentration in equilibrium with 5-nm particles, the toxicity of ions was at least 17 times higher than that obtained by dissolving silver nitrite (if not taking into account the effect of nanoparticles themselves). The mechanism of the toxicity of silver nanoparticles was found complex with an important role played by the adsorption of silver nanoparticles and the ions released from the particles on the cell surface. This mechanism could be described as some sort of synergy between nanoparticles and ions. While our study clearly showed the presence of this synergy, its detailed explanation is experimentally highly demanding, requiring a close cooperation between materials scientists, physical chemists, and biologists.
- MeSH
- antiinfekční látky metabolismus toxicita MeSH
- Chlorella vulgaris účinky léků metabolismus MeSH
- ionty metabolismus MeSH
- kovové nanočástice toxicita MeSH
- roztoky MeSH
- Scenedesmus účinky léků metabolismus MeSH
- stříbro metabolismus toxicita MeSH
- testy toxicity MeSH
- velikost částic MeSH
- Publikační typ
- časopisecké články MeSH
The freshwater alga Chlorella, a highly productive source of starch, might substitute for starch-rich terrestrial plants in bioethanol production. The cultivation conditions necessary for maximizing starch content in Chlorella biomass, generated in outdoor scale-up solar photobioreactors, are described. The most important factor that can affect the rate of starch synthesis, and its accumulation, is mean illumination resulting from a combination of biomass concentration and incident light intensity. While 8.5% DW of starch was attained at a mean light intensity of 215 µmol/(m2 s1), 40% of DW was synthesized at a mean light intensity 330 µmol/(m2 s1). Another important factor is the phase of the cell cycle. The content of starch was highest (45% of DW) prior to cell division, but during the course of division, its cellular level rapidly decreased to about 13% of DW in cells grown in light, or to about 4% in those kept in the dark during the division phase. To produce biomass with high starch content, it is necessary to suppress cell division events, but not to disturb synthesis of starch in the chloroplast. The addition of cycloheximide (1 mg/L), a specific inhibitor of cytoplasmic protein synthesis, and the effect of element limitation (nitrogen, sulfur, phosphorus) were tested. The majority of the experiments were carried out in laboratory-scale photobioreactors, where culture treatments increased starch content to up to about 60% of DW in the case of cycloheximide inhibition or sulfur limitation. When the cells were limited by phosphorus or nitrogen supply, the cellular starch content increased to 55% or 38% of DW, respectively, however, after about 20 h, growth of the cultures stopped producing starch, and the content of starch again decreased. Sulfur limited and cycloheximide-treated cells maintained a high content of starch (60% of DW) for up to 2 days. Sulfur limitation, the most appropriate treatment for scaled-up culture of starch-enriched biomass, was carried out in an outdoor pilot-scale experiment. After 120 h of growth in complete mineral medium, during which time the starch content reached around 18% of DW, sulfur limitation increased the starch content to 50% of DW.
- MeSH
- biomasa MeSH
- biotechnologie metody MeSH
- Chlorella vulgaris metabolismus MeSH
- dusík metabolismus MeSH
- fosfor metabolismus MeSH
- fotobioreaktory MeSH
- mikrořasy metabolismus MeSH
- síra metabolismus MeSH
- škrob biosyntéza metabolismus MeSH
- sluneční záření MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
A series of rhodanine derivatives was prepared. The synthetic approach, analytical and spectroscopic data of all synthesized compounds are presented. Lipophilicity of all the discussed rhodanine derivatives was analyzed using the RP-HPLC method. The compounds were tested for their ability to inhibit photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts and reduce chlorophyll content in freshwater alga Chlorella vulgaris. Structure-activity relationships between the chemical structure, physical properties and biological activities of the evaluated compounds are discussed. For majority of the tested compounds the lipophilicity of the compound and not electronic properties of the R1 substituent were decisive for PET-inhibiting activity. The most potent PET inhibitor was (5Z)-5-(4-bromobenzylidene)-2-thioxo-1,3-thiazolidin-4-one (IC(50) = 3.0 μmol/L) and the highest antialgal activity was exhibited by (5Z)-5-(4-chlorobenzylidene)-2-thioxo-1,3-thiazolidin-4-one (IC(50) = 1.3 μmol/L).
- MeSH
- Chlorella vulgaris účinky léků metabolismus MeSH
- chloroplasty účinky léků metabolismus MeSH
- fotosyntéza účinky léků MeSH
- hydrofobní a hydrofilní interakce MeSH
- nukleární magnetická rezonance biomolekulární MeSH
- rhodanin analogy a deriváty chemická syntéza farmakologie MeSH
- Spinacia oleracea účinky léků metabolismus MeSH
- transport elektronů účinky léků MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Unsubstituted, halogenated and/or alkylated pyrazine-2-carboxylic acid amides connected via -CONH- bridge with substituted anilines were synthesized using currently known synthetic pathways. The synthetic approach, analytical, spectroscopic, lipophilicity and biological data of 20 newly synthesized compounds are presented. Structure-activity relationships among the chemical structures, the antimycobacterial, antifungal, photosynthesis inhibiting and antialgal activity of the evaluated substituted N-phenylpyrazine-2-carboxamides are discussed. 5-tert-Butyl-6-chloro-N-(3-trifluoromethylphenyl)pyrazine-2-carboxamide (19) has shown the highest activity against Mycobacterium tuberculosis H(37)Rv (MIC=3.13 microg/mL). The highest antifungal effect against Trichophyton mentagrophytes, the most susceptible fungal strain tested, was found for N-(3-trifluoromethylphenyl)pyrazine-2-carboxamide (14, MIC=62.5 micromol/mL). The highest reduction of chlorophyll content in Chlorella vulgaris was found for pyrazine-2-carboxylic acid (3-trifluoromethylphenyl)amide (9, IC(50)=12.1 micromol/L).
- MeSH
- amidy farmakologie chemická syntéza chemie MeSH
- antibakteriální látky farmakologie chemická syntéza chemie MeSH
- antifungální látky farmakologie chemická syntéza chemie MeSH
- Cercopithecus aethiops MeSH
- Chlorella vulgaris metabolismus účinky léků MeSH
- chlorofyl metabolismus MeSH
- chloroplasty metabolismus účinky léků MeSH
- financování organizované MeSH
- herbicidy farmakologie chemická syntéza chemie MeSH
- mikrobiální testy citlivosti MeSH
- Mycobacterium tuberculosis účinky léků MeSH
- pyraziny farmakologie chemická syntéza chemie MeSH
- Spinacia oleracea metabolismus účinky léků MeSH
- Vero buňky MeSH
- vztahy mezi strukturou a aktivitou MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
