γ‐Linolenic acid production by <i>Arthrospira platensis</i> using different carbon sources

Abstract Arthrospira platensis (Spirulina) is an important source of pharmaceuticals and nutraceuticals such as γ‐linolenic acid (GLnA). Effects of several parameters including carbon source (glucose, ethanol, and acetic acid), type of addition (batch or fed‐batch), light intensity (2.0, 3.5, and 5.0 klx) were investigated in the mixotrophic cultivation of Spirulina (using both light and carbon source). The obtained Spirulina was analyzed in terms of biomass, lipid, and GLnA production. Compared to photoautotrophic conditions (i.e., when using light without external carbon source), the biomass concentration was found to be higher when Spirulina was grown mixotrophically. Similarly, the lipid content as well as the GLnA was found at higher levels when using mixotrophic conditions. Effects of different light intensities under photoautotrophic and mixotrophic conditions were studied. The highest final biomass concentration (2.17 g/L), lipid yield of culture medium (128 mg/L), and GLnA yield of the culture medium (32 mg/L) were obtained at the highest light intensity of 5.0 klx. It was also demonstrated that the biomass, lipid, and GLnA production under different light intensities, using ethanol and acetic acid, could be comparable and even better than those of glucose. Practical applications: Spirulina is an attractive source of functional components such as γ‐linolenic acid (GLnA). Results of this study suggest that carbon sources such as ethanol and acetic acid can also be used for the production of GLnA by Spirulina under mixotrophic cultivation (using light and external carbon source).