Arthrospira (Limnospira) maxima (A. maxima) and Chlorella vulgaris (Ch. vulgaris) are among the approved microalgae and cyanobacteria (MaC) in the food industry that are known to be safe for consumption. However, both organisms are controversial regarding their vitamin B12 content, due to the possible occurrence of pseudo-cobalamin. Concurrently, their nutrition profiles remain understudied. The main purpose of the present study was to identify their nutrition profiles, focusing mainly on vitamin B12, amino acids, and micronutrients under iron-induced hormesis (10 mg/L Fe in treated samples). Our findings indicate a higher B12 content in A. maxima compared to Ch. vulgaris (both control and treated samples). Using liquid chromatography with tandem mass spectrometry (LC-MS/MS), the cyanocobalamin content was determined as 0.42 ± 0.09 μg/g dried weight (DW) in the A. maxima control and 0.55 ± 0.02 μg/g DW in treated A. maxima, resulting in an insignificant difference. In addition, the iron-enriched medium increased the amount of iron in both tested biomasses (p < 0.01). However, a more pronounced (approximately 100×) boost was observed in Ch. vulgaris, indicating a better absorption capacity (control Ch. vulgaris 0.16 ± 0.01 mg/g Fe, treated Ch. vulgaris 15.40 ± 0.34 mg/g Fe). Additionally, Ch. vulgaris also showed a higher micronutrient content. Using both tested microalgae, meeting the sufficient recommended daily mineral allowance for an adult is possible. By combining biomass from A. maxima and Ch. vulgaris in a ratio of 6:1, we can fulfill the recommended daily allowance of vitamin B12 and iron by consuming 6 tablets/6 g. Importantly, iron hormesis stimulated amino acid composition in both organisms. The profile of amino acids may suggest these biomasses as promising potential nutrition sources.

• Klíčová slova
• Amino acids, Anemia, Cobalamin, Cyanobacteria, Deficiency, Iron, Microalgae,
• MeSH
• aminokyseliny * metabolismus   analýza   MeSH
• Chlorella vulgaris * chemie   metabolismus   růst a vývoj   MeSH
• mikrořasy chemie   metabolismus   růst a vývoj   MeSH
• mikroživiny * analýza   metabolismus   MeSH
• nutriční hodnota MeSH
• Spirulina * chemie   metabolismus   MeSH
• tandemová hmotnostní spektrometrie MeSH
• vitamin B 12 * metabolismus   analýza   MeSH
• železo metabolismus   analýza   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• aminokyseliny * MeSH
• mikroživiny * MeSH
• vitamin B 12 * MeSH
• železo MeSH

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.

• Klíčová slova
• Fatty acids, Lipids, Microalgae, Nutrient deficiency,
• MeSH
• biomasa MeSH
• biopaliva MeSH
• Chlorella vulgaris * metabolismus   MeSH
• dusík metabolismus   MeSH
• fosfor metabolismus   MeSH
• lipidy MeSH
• mastné kyseliny * metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• biopaliva MeSH
• dusík MeSH
• fosfor MeSH
• lipidy MeSH
• mastné kyseliny * MeSH

Amongst per- and polyfluoroalkyl substances (PFAS) compounds, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) have a high persistence in physicochemical and biological degradation; therefore, the accumulation of PFOS and PFOA can negatively affect aquatic organisms and human health. In this study, two microalgae species (Chlorella vulgaris and Scenedesmus obliquus) were exposed to different concentrations of a PFOS and PFOA mixture (0 to 10 mg L-1). With increases in the contact time (days) and the PFAS concentration (mg L-1) from 1 to 7, and 0.5 to 10, respectively, the cell viability, total chlorophyll content, and protein content decreased, and the decrease in these parameters was significantly greater in Scenedesmus obliquus. As another step in the study, the response surface methodology (RSM) was used to optimize the toxicity effects of PFAS on microalgae in a logical way, as demonstrated by the high R2 (>0.9). In another stage, a molecular docking study was performed to monitor the interaction of PFOS and PFOA with the microalgae, considering hydrolysis and the enzymes involved in oxidation-reduction reactions using individual enzymes. The analysis was conducted on carboxypeptidase in Chlorella vulgaris and on c-terminal processing protease and oxidized cytochrome c6 in Scenedesmus obliquus. For the enzyme activity, the affinity and dimensions of ligands-binding sites and ligand-binding energy were estimated in each case.

• Klíčová slova
• PFOA, PFOS, microalgae, toxicity, water,
• MeSH
• Chlorella vulgaris * metabolismus   MeSH
• fluorokarbony * toxicita   metabolismus   MeSH
• kapryláty toxicita   MeSH
• kyseliny alkansulfonové * toxicita   MeSH
• lidé MeSH
• mikrořasy * metabolismus   MeSH
• simulace molekulového dockingu MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• fluorokarbony * MeSH
• kapryláty MeSH
• kyseliny alkansulfonové * MeSH
• perfluorooctane sulfonic acid MeSH Prohlížeč
• perfluorooctane MeSH Prohlížeč
• perfluorooctanoic acid MeSH Prohlížeč

In vitro ACE-1 inhibitory peptides were characterised previously from a number of microalgal species including Spirulina platensis (peptide IAPG), Chlorella vulgaris (peptides FDL, AFL, VVPPA), Isochrysis galbana (peptide YMGLDLK), Chlorella sorokiniana (peptides IW and LW) and indeed Nannochloropsis oculata (peptides GMNNLTP and LEQ). The isolation of protein from Nannochloropsis oculata using a combination of ammonium salt precipitation and xylanase treatment of resulting biomass combined with molecular weight cut off filtration to produce a permeate and characterisation of bioactive peptides is described. The Angiotensin-1-converting enzyme (ACE-1) IC50 value for the generated permeate fraction was 370 µg/mL. Ninety-five peptide sequences within the permeate fraction were determined using mass spectrometry and eight peptides were selected for chemical synthesis based on in silico analysis. Synthesized peptides were novel based on a search of the literature and relevant databases. In silico, simulated gastrointestinal digestion identified further peptides with bioactivities including ACE-1 inhibitory peptides and peptides with antithrombotic and calcium/calmodulin-dependent kinase II (CAMKII) inhibition. This work highlights the potential of Nannochloropsis oculata biomass as both a protein and bioactive peptide resource, which could be harnessed for use in the development of functional foods and feeds.

• Klíčová slova
• Angiotensin Converting Enzyme-1 (ACE-1), Nannochloropsis oculata, functional foods, health, in silico analysis, metabolic syndrome, microalgae, pro-peptides, protein hydrolysates,
• MeSH
• Chlorella vulgaris * metabolismus   MeSH
• Chlorophyta * metabolismus   MeSH
• hmotnostní spektrometrie MeSH
• inhibitory ACE farmakologie   chemie   MeSH
• peptidy chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• inhibitory ACE MeSH
• peptidy MeSH

Selenium (Se) is an element with many commercial applications as well as an essential micronutrient. Dietary Se has antioxidant properties and it is known to play a role in cancer prevention. However, the general population often suffers from Se deficiency. Green algae, such as Chlorella vulgaris, cultivated in Se-enriched environment may be used as a food supplement to provide adequate levels of Se. We used Raman microspectroscopy (RS) for fast, reliable, and non-destructive measurement of Se concentration in living algal cells. We employed inductively coupled plasma-mass spectrometry as a reference method to RS and we found a substantial correlation between the Raman signal intensity at 252 cm-1 and total Se concentration in the studied cells. We used RS to assess the uptake of Se by living and inactivated algae and demonstrated the necessity of active cellular transport for Se accumulation. Additionally, we observed the intracellular Se being transformed into an insoluble elemental form, which we further supported by the energy-dispersive X-ray spectroscopy imaging.

• Klíčová slova
• Chlorella vulgaris, EDX, ICP-MS, Raman spectroscopy, algae, bioaccumulation, selenium,
• MeSH
• bioakumulace MeSH
• chemické látky znečišťující vodu analýza   metabolismus   MeSH
• Chlorella vulgaris chemie   metabolismus   MeSH
• Ramanova spektroskopie * MeSH
• selen analýza   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• chemické látky znečišťující vodu MeSH
• selen MeSH

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.

• Klíčová slova
• Anti-asthmatic effect, Extracellular polysaccharide, Green microalgae,
• 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
• Názvy látek
• alergeny MeSH
• antiastmatika MeSH
• cytokiny MeSH
• mediátory zánětu MeSH
• polysacharidy MeSH

Selenium (Se) is an indispensable microelement in our diet and health issues resulting from deficiencies are well documented. Se-containing food supplements are available on the market including Se-enriched Chlorella vulgaris (Se-Chlorella) which accumulates Se in the form of Se-amino acids (Se-AAs). Despite its popular uses, data about the bioaccessibility of Se-AAs from Se-Chlorella are completely missing. In the present study, gastrointestinal digestion times were optimized and the in vitro bioaccessibility of Se-AAs in Se-Chlorella, Se-yeast, a commercially available Se-enriched food supplement (Se-supplement) and Se rich foods (Se-foods) were compared. Higher bioaccessibility was found in Se-Chlorella (∼49%) as compared to Se-yeast (∼21%), Se-supplement (∼32%) and Se-foods. The methods used in production of Se-Chlorella biomass were also investigated. We found that disintegration increased bioaccessibility whereas the drying process had no effect. Similarly, temperature treatment by microwave oven also increased bioaccessibility whereas boiling water did not.

• Klíčová slova
• Bioaccessibility, Gas chromatography atmospheric pressure chemical ionization high resolution mass spectrometry (GC-APCI-HRMS), Methanesulfonic acid (PubChem CID: 6395), Methylselenocysteine (PubChem CID: 147004), Selenium enriched Chlorella vulgaris, Selenium enriched food supplement, Selenium rich foods, Selenized yeast, Selenoamino acids, Selenocysteine (PubChem CID: 6326983), Selenomethionine (PubChem CID: 15103),
• MeSH
• biomasa MeSH
• Chlorella vulgaris metabolismus   MeSH
• fortifikované potraviny analýza   MeSH
• hmotnostní spektrometrie metody   MeSH
• limita detekce MeSH
• plynová chromatografie s hmotnostně spektrometrickou detekcí metody   MeSH
• potravní doplňky analýza   MeSH
• Saccharomyces cerevisiae metabolismus   MeSH
• selen chemie   metabolismus   MeSH
• selenocystein analýza   metabolismus   MeSH
• selenomethionin analýza   metabolismus   MeSH
• teplota MeSH
• vysokoúčinná kapalinová chromatografie MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• selen MeSH
• selenocystein MeSH
• selenomethionin 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.

• Klíčová slova
• Calcium phosphate precipitates, DLVO theory, Microalgae, Surface interactions, Thermodynamic model,
• MeSH
• Chlorella vulgaris účinky léků   metabolismus   MeSH
• fosforečnany vápenaté farmakologie   MeSH
• mikrořasy účinky léků   metabolismus   MeSH
• termodynamika MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• calcium phosphate MeSH Prohlížeč
• fosforečnany vápenaté 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.

• Klíčová slova
• Diethyl ethoxymethylenemalonate, Liquid chromatography mass spectrometry, Methanesulfonic acid, Methionine, Protease XIV, Selenomethionine,
• 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
• Názvy látek
• diethyl (ethoxymethylene)malonate MeSH Prohlížeč
• malonáty MeSH
• methanesulfonic acid MeSH Prohlížeč
• methansulfonáty MeSH
• methionin MeSH
• pronasa MeSH
• selenomethionin MeSH

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.

• Klíčová slova
• Algae, Concentration of silver ions in equilibrium with silver nanoparticles, Silver ions, Silver nanoparticles, Toxicity, Uptake of silver by algae,
• 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
• Názvy látek
• antiinfekční látky MeSH
• ionty MeSH
• roztoky MeSH
• stříbro MeSH