Growth, chlorophyll α and protein of the marine microalga Isochrysis galbana in batch cultures with different salinities and high nutrient concentrations

Cultures of the marine microalga Isochrysis galbana were grown under 56 different nutrient concentration-salinity conditions, ranging from 1 to 64 mM NaNO3 and from 0 to 35‰ salinity. Salinity and nutrient concentration were found to be closely related to I. galbana growth and to the biochemical composition. Optimal growth conditions were between 15 and 35‰ salinity and nutrient concentrations of 2, 4 and 8 mM NaNO3, resulting in one doubling/day and a maximum cellular density of 20 × 106cells/ml. Variations in salinity and in nutrient concentration had a greater effect on the final biomass than on the growth velocity. Maximum values of chlorophyll α ml were found with 2, 4 and 8 mM NaNO3 and between 15 and 35‰ salinity. Chlorophyll α cell values were more homogeneously distributed between 15 and 35‰ salinity and 1 to 8 mM NaNO3, although maximum concentrations (37 pg chlorophyll α cell) were reached at 10-15‰ with all the nutrient concentrations. Protein per ml of culture and protein per cell were closely related to salinity and nutrient concentration. Maximum values of 387 μg/ml and 18.6 pg/cell were obtained at 15-35‰ salinity and 4-8 mM NaNO3. The nitrate-protein transformation rate was related to nutrient concentration. Maximum rate was 84% at 15‰ salinity and 1 mM NaNO3. Nutrient concentrations higher than 16 mM NaNO3 produced a strong decrease in the efficiency at all salinities

Biomass production and biochemical composition in mass cultures of the marine microalga Isochrysis galbana Parke at varying nutrient concentrations

Mass cultures of Isochrysis galbana were carried out with four nutrient concentrations ranging from 2 to 16 mM of NaNO3 and salinity 35‰. An air flow of 15 l/min maintained a CO2 transference rate sufficient to keep the pH below 8.4. Using these conditions, equations were calculated by a multiple non-linear least squares regression of order four, enabling predictions to be made of growth kinetics and chemical composition. Maximum cellular density of 65.5 × 106 cells/ml was obtained with 4 mM NaNO3. Cellular volume was constant in the different nutrient concentrations. Protein content reached a maximum value of 374 μg/ml at 4 mM of NaNO3, and this concentration also presented the maximum efficiency of transformation from nitrate to protein, i.e. 114%. As a result, lowest costs for harvesting are obtained at a nutrient concentration of 4 mM NaNO3. Efficiencies decreased to 15% as nutrient concentration increased. Maximum values of chlorophyll a (21.9 μg/ml) and carbohydrates (213 μg/ml) were also obtained with 4 mM NaNO3. In the logarithmic phase, the contents of protein, chlorophyll a, carbohydrates, RNA and DNA per cell were constant. Chlorophyll a reached values between 0.15 and 0.33 pg/cell in the stationary phase. Carbohydrate levels reached the maximum value of 3.16 pg/cell with 4 mM NaNO3 in the stationary phase. The levels of RNA/cell and DNA/cell were constant in all the nutrient concentrations tested and in both growth phases, and ranged from 1.15 to 1.71 pg/cell for RNA and from 0.006 to 0.014 pg/cell for DNA. Growth in mass cultures is closely coupled to changes in nutrient concentrations and variations occur in protein, chlorophyll a and carbohydrate contents, showing differences of 177%, 220% and 136%, respectively, in the stationary phase. This biochemical variability, mainly in protein content, must have a marked effect on the nutritive value of this microalga as a feed in mariculture

Mass culture and biochemical variability of the marine microalga Tetraselmis suecica Kylin (Butch) with high nutrient concentrations

Mass cultures of Tetraselmis suecica were carried out with four nutrient concentrations, ranging from 2 to 16 mM of NaNO3 and salinity 35‰. An air flow of 15 l/min maintained a CO2 transference rate sufficient to keep the pH below 8.4. Using these cultural conditions equations were calculated, by a multiple non-linear least squares regression of order four, enabling predictions to be made of growth kinetics and chemical composition. Maximum cellular densities of 7.83 × 106 and 7.15 × 106 cells/ml were obtained with 8 and 16 mM of NaNO3, respectively. Growth velocity ranged between 0.53 and 0.63 doublings (dbl)/day, although 0.98 dbl/day were reached with 16 mM of NaNO3. Volume increased with nutrient concentration from 252 to 905 μm3. Protein content reached maximum values of 306 μg/ml or 59.8 pg/cell. In the logarithmic phase, protein was regulated by nutrient concentration and decreased according to this concentration. Maximum efficiency of transformation from nitrate to protein was 108%, obtained at 2 mM of NaNO3. Efficiency decreased, to 14%, when nutrient concentration increased. This fact indicates that the lowest cost of harvesting is obtained with a nutrient concentration of 2 mM NaNO3. Chlorophyll a cell reached values between 3.1 and 3.8 pg/cell in the stationary phase. There was a relationship between nutrient concentration and chlorophyll α cell in the logarithmic phase, with an increase from 2.15 pg/cell to 3.74 pg/cell. Changes in chlorophyll α level are related to nitrogen depletion. Carbohydrate/cell was constant at values of 19.84-28.68 pg/cell in the logarithmic and stationary phases and was not related to nitrogen depletion. RNA/cell ranged from 4.17 to 5.48 pg/cell, except at 2 mM of NaNO3 when it was 2.77 pg/cell, probably due to nitrogen depletion. The level of DNA/cell was constant in all the nutrient concentrations assayed and ranged from 0.1 to 1.09 pg/cell. Great variability in the chemical composition of T. suecica has been shown. Growth in mass cultures is closely coupled to changes in nutrient concentrations and variations occur in protein, chlorophyll α and RNA content, showing differences of 215%, 190% and 203%, respectively, in the stationary phase. This biochemical variability, mainly in protein content, must have a marked effect on the nutritive value of this microalga as feed in mariculture

Growth and biochemical variability of the marine microalga Chlorella stigmatophora in batch cultures with different salinities and nutrient gradient concentration

[Abstract] Chlorella stigmatophora was cultured under 56 different combinations of nutrient-salinity concentrations, ranging from 1 to 64 mM NaNO3 and from 0 to 35%. salinity. Optimal growth conditions for obtaining maximum cellular densities were between 1 and 8 mM NaNO3 for any salinity, with a maximum growth rate at the logarithmic phase of 0·51 doublings d-1. Production over the 15 days as measured by chlorophyll a estimation were maximal between 5 and 20%. and 8–32 mM NaNO3. Maximum protein per ml occurred at 8 and 16 mM NaNO3 for all the salinities, whereas maximum protein/cell contents were obtained at 16 and 32 mM NaNO3. Protein content per ml and per cell was not affected by salinity. The nitrate/protein transformation rate is related to nitrate concentration. Maximum rates were obtained at 1 mM NaNO3, with values between 92% and 100%. Nutrient concentration produced changes in the biomass production and biochemical composition of this marine microalga, with wide variations in the chlorophyll a and protein content per ml (up to 700% and 500%, respectively). This microalga shows an important capacity to adapt to changes in salinity, ranging from freshwater (0%.) to oceanic sea-water (35%.). The significance of these results for the possible utilization of Ch. stigmatophora as source of Single Cell Protein (SCP) is discussed.Comisión Asesora de Investigación Científica y Técnica; AC86-000

The marine microalga Chlorella stigmatophora as a potential source of single cell protein: Enhancement of the protein content in response to nutrient enrichment

Mass cultures of Chlorella stigmatophora were carried out in order to obtain maximum protein production and to study the chemical variations in function of the nutrient concentration. Cultures reached maximum cellular densities of 2.2·108 cells/ml, with a growth velocity between 0.49 and 0.55 doublings/day. Carbohydrate content in the stationary phase ranged between 2.23 and 2.74 pg/cell, RNA between 0.78 and 1.36 pg/cell and DNA between 0.013 and 0.016 pg/cell. The maximum value for chlorophyll a was 0.13 pg/cell. Maximum protein content was obtained with a nutrient concentration of 16 mM of NaNO3, giving 4.85 pg/cell and a protein concentration of 0.7 g/l. The protein content can be manipulated by changes in the nutrient concentration, showing differences up to a 9.2-fold increase. This characteristic makes Chlorella stigmatophora a suitable source of single cell protein

Changes in protein, carbohydrates and gross energy in the marine microalga Dunaliella tertiolecta (Butcher) by nitrogen concentrations as nitrate, nitrite and urea

Cultures of the marine microalga Dunaliella tertiolecta were grown in nitrate, nitrite and urea at concentrations ranging from 0·25 to 16 mg atom. N/litre. Great biochemical variability has been shown in this microalga as a function of high nitrogen concentrations for all the sources used. Cellular protein and carbohydrates and gross energy per ml of culture increased proportionally to the increase in the N concentration, under conditions that maintain constant the N P ratio. Two kinds of cultures are defined: low nitrogen cultures 2 mg atom. N/litre. Variability mainly appears in the second type of cultures. Protein/cell values of up to 4·94, 5·47 and 1·41 times higher have been observed in nitrate, nitrite and urea cultures, respectively, when comparing protein/cell values obtained in high N cultures with those obtained in low N cultures. Similar variations have been observed in the carbohydrates/cell content, with values up to 3·16, 3·30 and 1·77 times higher in the high than in the low N cultures. Biochemical variability is greater in nitrate and nitrite cultures (inorganic sources of nitrogen) than in urea cultures (organic source of N). Lipid/carbohydrates ratio seems to be a convenient parameter for characterizing the physiological state of a microalgal population. This biochemical variability must have a marked effect on the value of this microalga as a source of single cell protein, chemicals or as feed in mariculture

Falla de estado y pérdida de bienestar para la sociedad

Se ha descrito en los textos que tratan la economía del sector público como parte de la microeconomía, sobre lo costosa que es para la sociedad la falla de mercado: a saber externalidades negativas como la contaminación, provisión insuficiente de bienes públicos y el monopolio que abusa de su poder de mercado, entre otras; pero poco se menciona sobre la falla del Estado, en que consiste, cual es el comportamiento del actor económico gobierno y como su accionar interfiere en el desarrollo de mercados sanos y competitivos, generando una inmensa destrucción de valor y riqueza, que se aprecia en pérdida de bienestar o pesos muertos en la sociedad. A continuación se enfatiza sobre la corrupción y las políticas de tipo populista como las fallas de Estado o Gobierno más graves incluyendo el enorme tamaño medido en término del ingreso nacional que está alcanzando el Estado del Bienestar. &nbsp

Composición florística y estructural de la vegetación arbórea de un bosque seco tropical del alto magdalena en el departamento del Tolima

92 p. Recurso ElectrónicoINTRODUCCIÓN 1. OBJETIVOS 1.1. OBJETIVO GENERAL 1.2. OBJETIVOS ESPECÍFICOS 2. MARCO TEÓRICO 2.1. ACERCA DEL BOSQUE SECO TROPICAL 2.2 ESTUDIO Y DINÁMICA DE LOS BOSQUES NATURALES 2.2.1. Estructura horizontal 2.2.2. Índice de valor de importancia (IVI) 2.2.3. Alfadiversidad 2.2.4. Índices convencionales 2.2.4.1. Índice de Shannon-Wiener 2.2.4.2. Índice de Simpson (D) 2.2.4.3. Índice de diversidad de Margalef 2.2.5. Distribución diamétrica 3. METODOLOGÍA 3.1. ÁREA DE ESTUDIO 3.2. COMPOSICIÓN FLORÍSTICA DE LOS FRAGMENTOS 3.3. MARCACIÓN Y UBICACIÓN GEOGRÁFICA DE LOS INDIVIDUOS EN LAS PARCELAS 3.4. TOMA DE MUESTRAS 4. RESULTADOS 4.1. COMPOSICIÓN FLORÍSTICA 4.2. CARACTERIZACIÓN FLORÍSTICA 4.2.1. Alfadiversidad 4.2.1.1. Índice de Simpson 4.2.1.2. Índice de Shannon 4.2.1.3. Índice de Margalef 4.2.2. Betadiversidad 4.3. ESTRUCTURA HORIZONTAL 4.4. DISTRIBUCIÓN DIAMÉTRICA 5. DISCUSIÓN 6. CONCLUSIONES REFERENCIAS ANEXO

Growth of the marine microalga Tetraselmis suecica in batch cultures with different salinities and nutrient concentrations

The marine microalga Tetraselmis suecica is known for its ability to tolerate a wide range of salt concentrations. Cultures were grown under 48 different nutrient concentration-salinity conditions, ranging from 2 to 64 mM NaNO3 and from 0 to 35‰ S. Salinity was more important for the growth rate of the microalgae when it was related to the nutrient concentration in the culture medium. Optimal growth conditions were between 25 and 35‰ salinity and nutrient concentrations of 2, 4 and 8 mM of NaNO3, resulting in 0.55 doublings/day and a maximum cellular density of 1.3 × 106 cells/ml. Variations in salinity and in nutrient concentration had a greater effect on the final biomass than on the growth velocity. The total protein of the culture and protein per cell increased when the salinity increased for a given nutrient concentration. The total protein of the cultures decreased when the nutrient concentration increased for a given salinity. Protein per cell decreased with increasing salinity up to 20‰ but from this point of the process was reversed. The nitrate-protein transformation rate increased with the salinity and decreased with increasing nutrient concentrations. The maximum rate was 64%

Response of the Marine Microalga Dunaliella tertiolecta to Nutrient Concentration and Salinity Variations in Batch Cultures

The marine microalga Dunaliella tertiolecta is known for its ability to tolerate a wide range of salt concentrations. Cultures were grown under 56 different nutrient concentration-salinity conditions. Optimal growth conditions were between 25 and 35 ‰ salinity and with nutrient concentrations between 8 and 32 times higher than the standard concentrations, resulting in maximum cellular densities between 8.41 x 106 and 16.74x 106 cells/ml. Growth is more affected by nutrient concentration than by salinity. No growth was obtained with the lowest salinities tested (0 and 5 ‰) at any of the nutrient concentrations used. Variations in salinity and in nutrient concentration had a greater effect on the final biomass than on the velocity of growth. Chlorophyll-a/ml was affected by salinity and nutrient concentrations and maximum values were found with 30 ‰ salinity and nutrient concentrations between 8 and 64 mM of NaNO3. Chlorophyll-a/cell reached maximum values between 2.02 and 3.51 pg/cell and is only significantly affected by the nutrient concentration. These maximum values were reached with low nutrient concentrations (1-2 mM of NaNO3). Protein per ml of culture and protein per cell were closely related to salinity and nutrient concentrations. Maximum protein per ml occurred at 20-25 ‰ salinity and 64mM of NaNO3, with values between 926 and 957 μml. Maximum protein/ cell concentrations were obtained also at 64 mM of NaNO3 for all the salinities. The nitrate-protein transformation rate was related to nutrient concentration and was independent of salinity. Maximum rate was 100% at 20 ‰ salinity and 1 mM of NaNO3. This rate decreased as nutrient concentrations increased