Search results for "algae"
showing 10 items of 403 documents
Isoprenoid biosynthesis in eukaryotic phototrophs: a spotlight on algae.
2011
Isoprenoids are one of the largest groups of natural compounds and have a variety of important functions in the primary metabolism of land plants and algae. In recent years, our understanding of the numerous facets of isoprenoid metabolism in land plants has been rapidly increasing, while knowledge on the metabolic network of isoprenoids in algae still lags behind. Here, current views on the biochemistry and genetics of the core isoprenoid metabolism in land plants and in the major algal phyla are compared and some of the most pressing open questions are highlighted. Based on the different evolutionary histories of the various groups of eukaryotic phototrophs, we discuss the distribution an…
Removal of algae from biological cultures: a challenge for electrocoagulation?
2014
BACKGROUND In the search for novel technologies for the treatment of urban wastewater, combined anaerobic–algae membrane bioreactors have become a very interesting choice. Recovery of algae produced in these reactors has become the key point to obtain a good economic efficiency with this technology. In this work, electrocoagulation is studied as an alternative for the coarse removal of algae from a biological culture. RESULTS Results demonstrate that the electrochemical technology is a suitable technology for this purpose allowing the removal of more than 90% of the algae without modifying significantly the pH and with an operating cost below 0.04 € m−3. The same general trends are observed…
Model performance of partial least squares in utilizing the visible spectroscopy data for estimation of algal biomass in a photobioreactor
2018
[EN] Spectroscopy technology and statistical methods (Partial Least Squares) have been integrated to develop a model that allows estimating the microalgal biomass in a photobioreactor. The model employing PLS combines the absorption spectrum measurements in the visible range (400-750 nm) with a microalgae cell density in a water sample. First, a calibration model was constructed using a calibration data set, and then, the predictive capacity of the model was determined by cross validation. Finally, an external validation of the predictive performance of the model was carried out with an independent data set. To test the accuracy of the model it was applied to different culture conditions yi…
Size-fractionated δ15N and δ13C isotope ratios elucidate the role of the microbial food web in the pelagial of Lake Tanganyika
2003
Food web structure of the pelagic community in Lake Tanganyika was studied using the stable nitrogen and carbon isotopes 15N and 13C. Size-fractionated seston, zooplankton, shrimps, medusae and fish were sampled in the northern part of Lake Tanganyika. Picoplankton fractions as well as cyanobacteria-dominated nano/microplankton fractions had very low nitrogen isotope signatures typical for nitrogen-fixing organisms. Fractions containing mainly dead organic matter (and associated bacteria) or nano/microalgae (chlorophytes and diatoms) had δ15N 2 to 4‰ higher. The low δ15N signatures of small cyclopoids and shrimps suggest they are feeding on nitrogen-fixing cyanobacteria (picoplankton or lar…
Biodiversity Patterns and Ecological Preferences of the Photobionts Associated With the Lichen-Forming Genus Parmelia
2021
The worldwide, ecologically relevant lichen-forming genusParmeliacurrently includes 41 accepted species, of which theParmelia sulcatagroup (PSULgp) and theParmelia saxatilisgroup (PSAXgp) have received considerable attention over recent decades; however, phycobiont diversity is poorly known inParmelias. lat. Here, we studied the diversity ofTrebouxiamicroalgae associated with 159 thalli collected from 30 locations, including nineParmeliaspp.:P. barrenoae, P. encryptata, P. ernstiae, P. mayi, P. omphalodes, P. saxatilis, P. serrana, P. submontana, andP. sulcata. The mycobionts were studied by carrying out phylogenetic analyses of the nrITS. Microalgae genetic diversity was examined by using …
Pulsed electric field (PEF) recovery of biomolecules from Chlorella: Extract efficiency, nutrient relative value, and algae morphology analysis
2023
This study investigated the effects of pulsed electric field (PEF) (3 kV/cm, 44 pulses, 99 kJ/kg), solvent (H2O or 50 % DMSO) and time (0, 10, 20, 30, 60, 90, 120 and 180 min) on the extraction of Chlorella antioxidant biomolecules and minerals. The results showed that PEF treatment increased the biomolecules recovery. For the extraction time of 120 min, more proteins and polyphenols were obtained using water, while more chlorophyll a and b, and carotenoids were obtained using 50 % DMSO as the extraction solvent. The extracts mineral concentration (PEF vs control) were analysed including Mg, P, Ca, Fe and Zn, and the Relative Nutrient Values results indicated that Chlorella H2O-extracts cou…
Botanical names in Southern Hemisphere Veronica (Plantaginaceae ): sect. Detzneria , sect. Hebe , and sect. Labiatoides
2007
The classification of the Southern Hemisphere Veronica complex is discussed in the light of recent findings that these segregate genera are nested within the hitherto northern Veronica clade. In order to render Veronica monophyletic, we transfer Chionohehe, Derwentia, Detzneria, Hebe, Hebejeebie, Heliohebe, Leonohebe, and Parahebe to Veronica subgen. Pseudoveronica. Correct names are listed for all species in Veronica subgen. Pseudoveronica, according to the International Code of Botanical Nomenclature. Those species previously included in Derwentia together with other Australian species of Veronica are now classified in Veronica sect. Labiatoides, that in Detzneria is now classified in Ver…
Chronic toxicity of methylparathion to the rotifer Brachionus calyciflorus fed on Nannochloris oculata and Chlorella pyrenoidosa
1993
The effect of sublethal levels of methylparathion (0,1, 3, 5, 7 mg 1−1) on the freshwater rotifer, Brachionus calyciflorus, during their entire life cycle was studied. Rotifers were fed on two species of unicellular algae: Nannochloris oculata and Chlorella pyrenoidosa; both algal concentrations were 5 × 105 cell ml−1.
Morphological determination of the phototrophic community composition of biological soil crusts in coastal sand dunes in northern Germany
2022
This dataset comprises the microbial community composition of biological soil crusts in north-German sand dunes. For this we obtained enrichment cultures of phototrophic microorganisms, by placing fragments of biocrusts of the same Petri dishes as used for sequencing, in Petri dishes with Bold Basal (1N BBM) agarized medium (Bischoff and Bold 1963). Cultures were grown under standard laboratory conditions: with a 12-hour alteration of light and dark phases and irradiation of 25 μmol photons m-2 s-1 at a temperature 20 ± 5 ºС. Microscopic study of these raw cultures began in the third week of cultivation. Morphological examinations were performed using Olympus BX53 light microscope with Noma…
Phytoplankton strategies and diversity under different nutrient levels and planktivorous fish densities in a shallow Mediterranean lake
2005
Two mesocosm experiments were carried out to investigate the dynamic effects of nutrients (nitrogen and phosphorus) and planktivorous fish additions on phytoplankton strategies and diversity. The phylogenetic and functional approaches were used to understand phytoplankton ecology in shallow Mediterranean lakes. The experimental approach is new for the study of algal functional groups. Nutrient loading and fish stocks enhanced biomass of small algae but decreased phytoplankton diversity and species richness. Faster species replacement and fluctuations in diversity occurred above loadings of 1 μM P and 21 μM N. Mesotrophic conditions favoured a diverse pool of species, including nostocales an…