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Marine Microalgae (marine + microalgae)
Selected AbstractsUse of Artificial Zeolites to Reduce Copper Toxicity to Two Marine MicroalgaeJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 2 2002Herlinda Gómez Villa [source] STEROLS AS BIOMARKERS IN GYMNODINIUM BREVE: DISTRIBUTION IN DINOFLAGELLATESJOURNAL OF PHYCOLOGY, Issue 2000J.D. Leblond The sterol composition of marine microalgae has been shown to be a chemotaxonomic property potentially of value in distinguishing members of different algal classes. For example, members of the class Dinophyceae display sterol compositions ranging from as few as two (cholesterol and dinosterol in Alexandrium tamarense) to as many as twelve in certain Heterocapsa species. Certain of these are 4-methyl sterols rarely found in other classes of algae. The ability to use sterol biomarkers to distinguish certain dinoflagellates such as the toxic species Gymnodinium breve, responsible for red tide events in the Gulf of Mexico, from other species within the same class would be of considerable scientific and economic value. Gymnodinium breve has been shown by others to possess two principal novel sterols, (24S)-4a-methylergosta-8(14), 22-dien-3b-ol (ED) and its 27-nor derivative (NED), not previously known to be present in other dinoflagellates. Characterization of free and esterified sterols from laboratory cultures of G. breve and of samples from a recent bloom in the Gulf of Mexico has confirmed the predominance of these two sterols. This has prompted a study of the sterol signatures of more than 30 dinoflagellates. ED and NED were shown also to be the primary sterols of the closely related dinoflagellates G. mikimotoi and G. galatheanum. They are also found as minor components of the more complex sterol profiles of other members of the Gymnodinium-Peridinium-Prorocentrum (GPP) taxonomic group. The more widespread distribution of this sterol pattern is consistent with the known close relationship between G. breve and G. mikimotoi. [source] Antioxidative Responses of Two Marine Microalgae During Acclimation to Static and Fluctuating Natural UV RadiationPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 6 2009Paul J. Janknegt Photoacclimation properties were investigated in two marine microalgae exposed to four ambient irradiance conditions: static photosynthetically active radiation (PAR: 400,700 nm), static PAR + UVR (280,700 nm), dynamic PAR and dynamic PAR + UVR. High light acclimated cultures of Thalassiosira weissflogii and Dunaliella tertiolecta were exposed outdoors for a maximum of 7 days. Dynamic irradiance was established by computer controlled vertical movement of 2 L bottles in a water filled basin. Immediate (<24 h), short-term (1,3 days) and long-term (4,7 days) photoacclimation was followed for antioxidants (superoxide dismutase, ascorbate peroxidase and glutathione cycling), growth and pigment pools. Changes in UVR sensitivity during photoacclimation were monitored by measuring UVR-induced inhibition of carbon assimilation under standardized UV conditions using an indoor solar simulator. Both species showed immediate antioxidant responses due to their transfer to the outdoor conditions. Furthermore, upon outdoor exposure, carbon assimilation and growth rates were reduced in both species compared with initial conditions; however, these effects were most pronounced in D. tertiolecta. Outdoor UV exposure did not alter antioxidant levels when compared with PAR-only controls in both species. In contrast, growth was significantly affected in the static UVR cultures, concurrent with significantly enhanced UVR resistance. We conclude that antioxidants play a minor role in the reinforcement of natural UVR resistance in T. weissflogii and D. tertiolecta. [source] Microalgae for oil: Strain selection, induction of lipid synthesis and outdoor mass cultivation in a low-cost photobioreactorBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2009Liliana Rodolfi Abstract Thirty microalgal strains were screened in the laboratory for their biomass productivity and lipid content. Four strains (two marine and two freshwater), selected because robust, highly productive and with a relatively high lipid content, were cultivated under nitrogen deprivation in 0.6-L bubbled tubes. Only the two marine microalgae accumulated lipid under such conditions. One of them, the eustigmatophyte Nannochloropsis sp. F&M-M24, which attained 60% lipid content after nitrogen starvation, was grown in a 20-L Flat Alveolar Panel photobioreactor to study the influence of irradiance and nutrient (nitrogen or phosphorus) deprivation on fatty acid accumulation. Fatty acid content increased with high irradiances (up to 32.5% of dry biomass) and following both nitrogen and phosphorus deprivation (up to about 50%). To evaluate its lipid production potential under natural sunlight, the strain was grown outdoors in 110-L Green Wall Panel photobioreactors under nutrient sufficient and deficient conditions. Lipid productivity increased from 117 mg/L/day in nutrient sufficient media (with an average biomass productivity of 0.36 g/L/day and 32% lipid content) to 204 mg/L/day (with an average biomass productivity of 0.30 g/L/day and more than 60% final lipid content) in nitrogen deprived media. In a two-phase cultivation process (a nutrient sufficient phase to produce the inoculum followed by a nitrogen deprived phase to boost lipid synthesis) the oil production potential could be projected to be more than 90 kg per hectare per day. This is the first report of an increase of both lipid content and areal lipid productivity attained through nutrient deprivation in an outdoor algal culture. The experiments showed that this marine eustigmatophyte has the potential for an annual production of 20 tons of lipid per hectare in the Mediterranean climate and of more than 30 tons of lipid per hectare in sunny tropical areas. Biotechnol. Bioeng. 2009;102: 100,112. © 2008 Wiley Periodicals, Inc. [source] | ||||||||||