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Data of Thesis

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Author: Carolina Tolomini Miranda.

Title: Effects of light intensity in growth and lipid production by Akistrodesmus sp. (Chlorophyceae) for biodiesel production. 

Year: 2011.            Full text (in Portuguese)

Abstract:

The variation in light intensity can promote changes in morphology and photosynthetic characteristics of microalgae. However, is still unclear if high light intensities could have a role in lipids production. The aim of this study was to investigate the variation of lipids accumulation during growth of a strain of Ankistrodesmus sp. (ANRF-01) under different light intensities: 900, 1400 and 2000 μmols photons.m-2.s-1. Cultures were grown during 20 days in bath culture conditions, ASM-1 medium, at 24±1ºC, pH 8 and light\dark cycles of 12 hours. Sampling was done every two days for analysis of cell number, chlorophyll-a and carbohydrates concentration. Lipid production was determined at: 4th (exponential phase), 8th (early stationary phase), 12th and 19th (stationary phase) days. The maximum yield of increase (defined as maximum cells number divided of the inoculum cells) was 0,62 in 900 μmols photons.m-2.s-1. In 1400 and 2000 μmols photons.m-2.s-1 these rates were 0,59 and 0,58 respectively. Biomass production was highest at the lowest light intensity (894 ± 53mg.L-1). These values were 841 ± 40.3mg.L-1 for 1400 μmols photons.m-2.s-1 and 771 ± 3.2mg.L-1 for 2000 μmols photons.m-2.s-1. In contrast the highest percentages of lipid extracts were obtained in 2000 μmols photons.m-2.s-1, reaching 46 ± 7.3% of biomass, while in 900 μmols photons.m-2.s-1 it reached 40 ± 4% and 33 ± 7,8% in 1400 μmols photons.m-2.s-1. The highest yield of fatty acid esters (68 ± 20.5%) were obtained in 1400 μmols while in 900 and 2000 μmols photons.m-2.s-1 were 37±4.4 and 33±5.7% respectively. Gas chromatography analysis showed that ester profile is adequate to biodiesel production. Data showed that light intensities usually found in surface water column are high enough to allow a good biomass and synthesis of fatty acid esters adequate to biodiesel production.

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