A brief period of darkness induces changes in fatty acid biosynthesis towards accumulation of saturated fatty acids in Chlorella vulgaris UMT-M1 at stationary growth phase.

Abstract

The effects of a brief (3days) and prolonged (6days) period of incubation in darkness and light on the biomass content, lipid content and fatty acid profile in Chlorella vulgaris UMT-M1 were determined. Three days of incubation in darkness increased saturated fatty acid (SFA) content from 34.0 to 41.4% but decreased monounsaturated fatty acid (MUFA) content from 36.7 to 29.8%. Palmitic acid (C16:0) contentwas increased from 23.2 to 28.9%, whereas oleic acid (C18:1) contentwas reduced from 35.4 to 28.8%. Total oil content was slightly decreased from 20.4 to 18.7% after 3days of darkness, without a significant reduction in biomass compared to 3days of incubation in light. Biomass and oil content was highest in cultures incubated for 6days in light, however the stimulatory and inhibitory effects of darkness (or light) on SFA and MUFA content was no longer present at 6days of incubation. Findings from this study suggests that fatty acid composition in C. vulgaris could be modulated to favor either C16:0 or C18:1 by a brief period of either darkness or light incubation, prior to harvesting.