Background: Nowadays, chlorophycean microalgae have attained a broad-spectrum attention
as a potential candidate for biomass and bioenergy production. Despite their appreciated
benefits, one of major problems is their low biomass and lipid productivity. Here we investigated
the heterotrophic culture in shake flasks and stirred tank bioreactor to improve the lipid and biomass
production in a naturally isolated strain of Chlorella vulgaris.
Methods: A naturally isolated C. vulgaris strain was cultivated in BG-11 medium in shake flask
and bioreactor. Its biochemical composition and growth kinetic parameters were investigated.
Results: The biomass productivity was improved (3.68 fold) under heterotrophic culture compared
to basal autotrophic culture condition in shake flask experiment. The total lipid content increased to
44% of total Dry Cell Weight (DCW) during heterotrophic growth after 21 days. Moreover, a great
Fatty Acid Methyl Esters (FAME) yield was observed under heterotrophic cultivation. Total biomass
and lipid content of microalgae in bioreactor experiment increased to 4.95 and 2.18 g L-1 respectively,
during 5 days of the experiment compared to its basic autotrophic culture.
Conclusion: The techno-economic aspects of exploiting C. vulgaris as a biodiesel feedstock werealso
evaluated. The results imply that heterotrophic cultivation could compensate the low biomass
productivity in microalgae for green energy production. Ever growing rates of established patents
on application of various genetic and bioengineering-based methods have made it possible to
achieve higher lipid contents with reduced total costs for microalgal biodiesel production as well.
Keywords: Biomass, Chlorella vulgaris, heterotrophic culture, lipid, techno-economic assessment, food supplements.
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