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

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 EPAwith 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.