Evaluation of microalgae as vegetarian source of dietary polyunsaturated fatty acids under autotrophic growth conditions

Abstract

Twelve indigenous microalgae, comprising of three fresh water and nine marine strains, were evaluated for their potential as source of dietary polyunsaturated fatty acids (PUFAs) under autotrophic growth conditions. The microalgal lipids showed higher content of omega-3 PUFAs as reflected in lower omega-6 to omega-3 ratios between 0.1 and 0.75. Alpha linolenic acid (ALA), was the predominant omega-3 PUFA in fresh water green algal strains. Scenedesmus dimorphus and Chlorococcum sp. showed higher content of ALA with an average productivity of 3 mgL−1 day−1. Long chain omega-3 PUFAs, eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) were observed in marine strains. Nannochloropsis and Chlorella sp. had higher content of EPA with Chlorella sp. showing an average productivity of 2 mgL−1 day−1. Isochrysis sp. showed higher DHA content with average productivity of 0.37 mgL−1 day−1. Presence of EPA and DHA contributed to higher degree of unsaturation in lipids of marine strains. Among the marine strains, the growth and lipid profile of Nannochloropsis sp. and Chlorella sp. remained unaffected by growth medium, whereas strains like T. theli showed a differential response to media. Spirulina platensis SP6 from CFTRI algal culture repository was also included as a reference strain since its nutritional benefits have been well elucidated. Gamma Linolenic acid (GLA) was the predominant PUFA in Spirulina sp. with an average productivity of 0.73 mgL−1 day−1.