Building a better mousetrap II: Using Design of Experiments with unconfounded ions to compare the growth of different microalgae

• Unconfounded media variations were used to examine microalgal growth.
• The effects of variations in NH4+, NO3−, Na+, K+, PO4−, and Cl− were studied.
• Two strains of Chlorella show significant physiological and functional differences.
• Different microalgae show different effects for growth and lipid content.
• Future work could lead to the development of novel media.

A large number of unconfounded media variations were used with a Scheffe Mix Model to examine in an unambiguous fashion the effects of variations in six important ions; NH4+, NO3−, Na+, K+, PO4−, and Cl−, on the growth of Chlorella vulgaris. This allows several novel observations on media components, for example, the inhibitory effects of chloride, to be made. Using a side by side comparison, it is shown that two strains of Chlorella show significant physiological and functional differences brought out by this approach. Testing selected formulations with a diverse set of algae demonstrated different effects on both growth and cellular lipid content, in some cases driving significant lipid production. This suggests that future work using a larger portion of media composition space could lead to the development of novel media supporting maximal biomass production and lipid production.