Biodiesel production from marine cyanobacteria cultured in plate and tubular photobioreactors.

Carbon (neutral) based renewable liquid biofuels are alternative to petroleum derived transport fuels that contribute to global warming and are of a limited availability. Microalgae based biofuels are considered as promising source of energy. Lyngbya sp. and Synechococcus sp. were studied for the possibility of biodiesel production in different media such as ASNIII, sea water enrichment medium and BG11. The sea water enrichment medium was found superior in enhancing the growth rate of these microalgae. Nitrogen depletion has less effect in total chlorophyll a content, at the same time the lipid content was increased in both Lyngbya sp. and Synechococcus sp. by 1.4 and 1.2 % respectively. Increase in salinity from 0.5-1.0 M also showed an increase in the lipid content to 2.0 and 0.8 % in these strains; but a salinity of 1.5 M has a total inhibitory effect in the growth. The total biomass yield was comparatively higher in tubular LED photobioreactor than the fluorescent flat plated photobioreactor. Lipid extraction was obtained maximum at 60 ºC in 1:10 sample: solvent ratio. GC-MS analysis of biodiesel showed high content of polyunsaturated fatty acids (PUFA; 4.86 %) than saturated fatty acid (SFA; 4.10 %). Biodiesel production was found maximum in Synechococcus sp. than Lyngbya sp. The viscosity of the biodiesel was closely related to conventional diesel. The results strongly suggest that marine microalgae could be used as a renewable energy source for biodiesel production.

Crecimiento y producción de metabolitos de la cianobacteria marina Synechococcus sp. (Chroococcales) en función de la irradiancia

Growth and metabolite production of the marine cyanobacterium Synechococcus sp. (Chroococcales) in function to irradiance. Changes in salinity, temperature and irradiance during wet and dry seasons have induced metabolic versatility in cyanobacteria from saline environments. Cyanobacteria from these environments have biotechnological potential for the production of metabolites with pharmaceutical and industrial interest. We studied the growth, dry mass and metabolite production of the cyanobacterium Synechococcus sp. MOF-03 in function of irradiance (78, 156 and 234 µmol q m-2 s-1). All batch cultures were maintained by triplicate in constant aeration, 12:12 h photoperiod, 30 ±2ºC and 35‰. Maximum values of protein, carbohydrates and lipids, of 530.19 ±11.16, 408.94 ±4.27 and 56.20 ±1.17 µg ml-1, respectively, were achieved at 78 µmol q m-2 s-1. Pigments, analyzed by HPLC, showed maximum values at 78 µmol q m-2 s-1 for chlorophyll a with 7.72 ±0.16 µg ml-1, and at 234 µmol q m-2 s-1 for ß-carotene and zeaxanthin with 0.70 ±0.01 and 0.67 ±0.05 µg ml-1. Chlorophyll a:ß-carotene ratio decreased from 17.15 to 6.91 at 78 and 234 µmol q m-2 s-1; whereas ß-carotene:zeaxanthin ratio showed no changes between 78 and 156 µmol q m-2 s-1, around 1.21, and decreased at 234 µmol q m-2 s-1, to 1.04. Also, this cyanobacterium produced the greatest cell density and dry mass at 156 µmol q m-2 s-1, with 406.13 ±21.74 x106 cell ml-1 and 1.49 ±0.11 mg ml-1, respectively. Exopolysaccharide production was stable between 156 y 234 µmol q m-2 s-1, around 110 µg ml-1. This Synechococcus strain shows a great potential for the production of enriched biomass with high commercial value metabolites. Rev. Biol. Trop. 56 (2): 421-429. Epub 2008 June 30.

Las cianobacterias de ambientes salinos presentan una versatilidad metabólica inducida por los cambios de salinidad, temperatura e irradiancia, durante los períodos de sequía y lluvias. Por ello es importante la búsqueda en estos ambientes de cianobacterias con potencial biotecnológico para la producción de metabolitos de interés farmacéutico e industrial. Se reporta el crecimiento, masa seca y producción de metabolitos de la cianobacteria Synechococcus sp. MOF-03 en función de la irradiancia (78, 156 y 234 µmol q m-2 s-1). Los cultivos discontinuos por triplicado, fueron mantenidos con aireación constante, fotoperiodo 12:12 h, 30 ±2ºC y a 35‰. Los máximos valores de proteínas, carbohidratos y lípidos de 530.19 ±11.16, 408.94 ±4.27 y 56.20 ±1.17 µg ml-1 respectivamente, fueron obtenidos a 78 µmol q m-2 s-1. Los pigmentos, analizados por HPLC, mostraron los máximos a 78 µmol q m-2 s-1 para clorofila a con 7.72 ±0.16 µg ml-1; y a 234 µmol q m-2 s-1 para ß-caroteno y zeaxantina con 0.70 ±0.01 and 0.67 ±0.05 µg ml-1. La relación clorofila a:ß-caroteno disminuyó de 17.15 hasta 6.91 a 78 y 234 µmol q m-2 s-1; mientras que la relación ß-caroteno:zeaxantina se mantuvo sin cambios entre 78 y 156 µmol q m-2 s-1, con cerca de 1.21 y disminuyó a 234 µmol q m-2 s-1 a 1.04. La cianobacteria produjo la mayor densidad celular y masa seca a 156 µmol q m-2 s-1, con 406.13 ±21.74 x106 cel ml-1 y 1.49 ±0.11 mg ml-1 respectivamente. La producción de exopolisacáridos se mantuvo alrededor de 110 µg ml-1 entre 156 y 234 µmol q m-2 s-1. Así, esta cepa de Synechococcus muestra un gran potencial para la producción de biomasa enriquecida con metabolitos de alto valor comercial.