Oil and eicosapentaenoic acid production by the diatom Phaeodactylum tricornutum cultivated outdoors in Green Wall Panel (GWP®) reactors (original) (raw)
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Potential of Phaeodactylum tricornutum for Biodiesel Production under Natural Conditions in Chile
Energies
Diatoms are very diverse and highly productive organisms, found in a wide variety of environments. This study aims to analyze the growth and lipid composition of Phaeodactylum tricornutum, cultured in an outdoor pilot-scale bubble column photobioreactor under natural conditions in Chile for biodiesel production. Results showed that P. tricornutum cultures reached their highest biomass concentration (0.96 ± 0.04 kg m −3) after 14 days of culturing, at the stationary phase, with a volumetric productivity of 0.13 kg m −3 d −1. Biomass samples showed a total lipid content of 9.08 ± 0.38 wt %. The fatty acid methyl ester analysis revealed a composition of 24.39% C16-C18 fatty acids, 42.34% saturated fatty acids, 21.91% monounsaturated fatty acids and 31.41% polyunsaturated fatty acids. These findings suggest that P. tricornutum oil can be used as an alternative raw material for the production of biodiesel capable of meeting international quality standards.
Lipid production by Phaeodactylum tricornutum
Bioresource Technology, 1991
The marine diatom Phaeodactylum tricornutum Bohlin is a potential source of the pharmaceutically valuable w3 polyunsaturated fatty acid eicosapentaenoic acid (EPA). The results of indoor continuous growth of Phaeodactylum tricornutum Bohlin are reported.
Eicosapentaenoic acid-rich biomass production by the microalga in a continuous-flow reactor
Bioresource Technol, 1996
The marine diatom Phaeodactylum tricornutum Bohlin is a potential source of the pharmaceutically valuable w3 polyunsaturated fatty acid eicosapentaenoic acid (EPA). The results of indoor continuous growth of Phaeodactylum tricornutum Bohlin are reported. The relationships between dilution rate (D), nitrate concentration and chemical composition were studied. Higher biomass and lipid productivities were obtained at low D values. EPA was found to be an intermediate metabolite and the best productivity (6 mg 1-r day-r) was achieved for D values ranging from 0.32 to 0.50 day-'. Under optimum conditions, 84 and 1170, respectively, of total recovered EPA were present in monogalactosyldia~lglycerol (MGDG) and in triacylglycerol (TG) moieties, respectively. Recorded EPAI! and EPA/20,4 03 ratios for all tested dilution rates were among the highest values ever reported, showing EPA purification to be easier to perform from this starting material than from many others commonly in use.
Journal of Applied Phycology, 2017
Microalgal biotechnology is always in demand for new fast-growing and oil-rich microalgal strains for different industries. A fusiform diatom strain with robust growth attributes was isolated from Coliumo's Bay in the Biobio Region, Chile, in 2005. In order to determine the taxonomic identity of the strain, partial sequences of 18S rDNA and ITS region were obtained. Sequence analysis revealed 99% identity with strains of Phaeodactylum tricornutum Bohlin emend. The effect of autotrophic (combination of irradiances, nitrate, and phosphate concentrations) and mixotrophic (addition of sodium acetate under low light) culture conditions was evaluated on growth and lipid accumulation. Hierarchical analysis clustered the autotrophic culture conditions in three main groups of common growth and lipid accumulation responses. Independently on the irradiance, the lowest nitrate and phosphate concentrations induced the highest total lipid accumulation (26-29% lipids per biomass dry weight) and the maximum saturated fatty acid ratio (ca. 42% of total fatty acids), without negative effect on growth; conversely, the highest nitrate and phosphate concentrations stimulated growth and PUFA proportion (20-25% of total fatty acids), but not total lipid accumulation (ca. 15% lipids per biomass dry weight). On the other hand, mixotrophic conditions stimulated growth but not lipid accumulation. Saturated and monounsaturated fatty acid fractions increased as acetate was added while PUFA fraction decreased. Physiological plasticity demonstrated by the Chilean strain of P. tricornutum studied, when faced with different growing conditions, makes it a potential candidate for commercial oil production for different markets, such as biodiesel or feed/food.
Freshwater diatoms as source of lipids for biofuel
Until recently, biodiesel production has been derived from terrestrial plants such as soybean and canola, leading to competition between biodiesel production and agricultural production for source materials. Microalgae have the potential to synthesize 30 times more oil per hectare than terrestrial plants without competing for agricultural land. We examined four genera (Cyclotella, Aulacoseira, Fragilaria, Synedra) of common freshwater diatoms (Bacillariophyceae) for growth and lipid content in deWned medium (sD11) that replicates hypereutrophic conditions in lakes and wastewater treatment plant eZuents and optimized the medium for silicon content. Cyclotella and Aulacoseira produced the highest levels of total lipids, 60 and 43 g total lipids/ml, respectively. Both diatoms are rich in fatty acids C14, C16, C16:1, C16:2,7,10, and C22:5n3. Of the diatoms examined, Cyclotella reached the highest population density (>2.5 £ 10 6 cells/ml) in stationary phase when many of the cells appeared to be Wlled entirely with oil. Silicon enrichment studies indicated that for optimal utilization of phosphorus and nitrogen by diatoms growing in wastewater eZuent, the amount of silicon present or added to the eZuent should be 17.5 times the mass of phosphorus in the eZuent. With high growth rates, high lipid contents, and rapid settling rates, Cyclotella and Aulacoseira are candidates for biodiesel production.
Potential of lipid metabolism in marine diatoms for biofuel production
Biotechnology for Biofuels, 2015
Background: Diatoms are an ecologically relevant group of microalgae that are not commonly considered for bio-oil production even if they are responsible for massive blooms at sea. Seventeen diatom species were screened for their capacity to produce biomass and lipids, in relation to their growth rate. Triglyceride levels were also assessed as a preferential source of biofuels. Results: Using statistical analysis, two centric diatoms, Thalassiosira weissflogii and Cyclotella cryptica, were selected as good candidates for oil production. Lipid levels significantly increased when the two diatoms were cultivated in a two-stage process under nitrogen limitation. The effect was less pronounced in cultures where silicon was reduced to 20% of the standard supply. Nitrogen limitation did not affect growth rates but led to lipid remodeling and de novo synthesis of triacylglycerols. Conclusions: Triacylglycerols in T. weissflogii and C. cryptica can account for up to 82% and 88% of total glycerolipids, thereby suggesting that the two species are promising candidates for large-scale experimentation for biofuel production.
Nutrient resupplementation arrests bio-oil accumulation in Phaeodactylum tricornutum
Applied Microbiology and Biotechnology, 2013
Phaeodactylum tricornutum is a marine diatom in the class Bacillariophyceae and is important ecologically and industrially with regards to ocean primary production and lipid accumulation for biofuel production, respectively. Triacylglyceride (TAG) accumulation has been reported in P. tricornutum under different nutrient stresses, and our results show that lipid accumulation can occur with nitrate or phosphate depletion. However, greater lipid accumulation was observed when both nutrients were depleted as observed using a Nile Red assay and fatty acid methyl ester (FAME) profiles. Nitrate depletion had a greater effect on lipid accumulation than phosphate depletion. Lipid accumulation in P. tricornutum was arrested upon resupplementation with the depleted nutrient. Cells depleted of nitrogen showed a distinct shift from a lipid accumulation mode to cellular growth postresupplementation with nitrate, as observed through increased cell numbers and consumption of accumulated lipid. Phosphate depletion caused lipid accumulation that was arrested upon phosphate resupplementation. The cessation of lipid accumulation was followed by lipid consumption without an increase in cell numbers. Cells depleted in both nitrate and phosphate displayed cell growth upon the addition of both nitrate and phosphate and had the largest observed lipid consumption upon resupplementation. These results indicate that phosphate resupplementation can shut down lipid accumulation but does not cause cells to shift into cellular growth, unlike nitrate resupplementation. These data suggest that nutrient resupplementation will arrest lipid accumulation and that switching between cellular growth and lipid accumulation can be regulated upon the availability of nitrogen and phosphorus.
Renewable Energy, 2016
The lipid content, composition and productivity of the marine benthic diatom Halamphora coffeaeformis were studied in order to evaluate its potential as feedstock for biodiesel production. Cultures were carried out in two stages: I) in photobioreactors (PBRs) to increase the biomass as inoculum for larger volumes, and II) in raceway ponds to increase naturally the triacylglycerol (TAG) content during the stationary growth phase. Biomass concentrations of 0.64 g L À1 and 0.23 g L À1 were reached in the PBR and the raceway pond, respectively. Total lipid content was 54.4 (±11.6) % ash free dry weight (AFDW) in the raceway pond on day 19 (harvest day), with a neutral lipid content of 34% AFDW. The TAG productivity in the raceway pond was 1.2 mg L À1 d À1. The indicators of biodiesel, calculated from fatty acid profile composition, showed that H. coffeaeformis oil was of good quality, according to international standards. Some hypothetical aspects are proposed in order to improve lipid productivity and net energy ratio in processes at larger scales.