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Biodiesel production from Stichococcus strains at laboratory scale



BACKGROUND: This paper reports the results of an experimental campaign of autotrophic cultures of Stichococcus strains aiming at selecting the most promising strain for biofuel production. The strain selected—S. bacillaris 158/11—was cultivated in 1 L lab-scale bubble column photobioreactors under fed-batch and semi-continuous conditions. A Bold basal medium supplemented with NaNO3 as nitrogen source was adopted. Tests were carried out at 23 °C, 140 µE m−2 s−1, and air flow rate ranging between 0.4 and 4 vvm. Cultures were characterized in terms of pH, concentration of total nitrogen, total organic carbon, total inorganic carbon, biomass, lipid fraction and methyl-ester distribution of transesterified lipids.

RESULTS:S. bacillaris 158/11 proved to be the best strain to produce biodiesel. Methyl-ester distribution was characterized by a large fraction of methyl palmitate, methyl linolenate, methyl linoleate, and methyl oleate along with phytol. The process photosynthetic efficiency—fraction of available light stored as chemical energy - was about 1.5%. Specific biomass productivity was ∼60 mgDM L−1 day−1 under the semi-continuous conditions tested. Total lipid productivity was 14 mg L−1 day−1 at a dilution rate of 0.050 L day−1.

CONCLUSION:S. bacillaris 158/11 is a potential strain for massive microalgae cultures for biofuel production. Higher biomass/total-lipid productivity could be obtained in sunlight. Copyright © 2011 Society of Chemical Industry