The effects of flue gas, light intensity and nitrogen source on the carbon partitioning and biodiesel source potential of Heterosigma akashiwo and Chattonella subsalsa

Bianco, Colleen
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University of Delaware
This work aims to evaluate Heterosgima akaskiwo and Chattonella subsalsa as biodiesel feedstocks when grown on CO2 and NO rich model flue gas. The growth rates of H. akaskiwo and C. subsalsa where higher when the cultures were bubbled with flue gas compared to when bubbled with air. The ability of H. akashiwo and C. subsalsa to survive high concentrations of NO may be due to a hydrid nitrate reductase, (NR2- 2/2HbN), that may detoxify and convert nitric oxide to nitrate. H. akashiwo was able to grow to a higher cell density when bubbled with flue gas compared to when bubbled with air under nitrate deficient conditions, indicating that H. akashiwo may be able to use NO as an inorganic nitrogen source. When grown on flue gas, both H. akashiwo and C. subsalsa accumulated significantly more carbohydrates than when grown on air. This indicates that the high CO2 concentration in the flue gas was assimilated as carbohydrates, a direct product of photosynthesis. When H. akashiwo was grown at a high light intensity, the growth rate was not significantly different from that at a low light intensity, which suggests that light limitation during mass cultivation would not be an issue during biodiesel production. This work also explored the transcript abundance of key fatty acid synthesis genes to further understand fatty acid synthesis in microalgae. Beta-ketoacyl-ACP synthase transcript abundance varied with almost every treatment and may be a key regulator when H. akashiwo and C. subsalsa are under environmental stress. Overall, this works demonstrates that both H. akaskiwo and C. subsalsa can grown on model flue gas and be producers of high quality biodiesel.
Heterosigma akashiwo , Biofuels , Nitric oxide , Flue gas