Background: Algae offers many advantages as a biofuels source including: high growth rates, high lipid content, the ability to grow on non-agricultural land, and the versatility to improve strains rapidly and produce co-products. Extensive research is ongoing to make algae biofuels a more financially attractive alternative energy option; however, it is increasingly becoming evident that the economic viability of many algae-based fuels may hinge upon the identification of high-value co-products. This work evaluated the potential of using one such co-product, algae extract, as a nutrient source in cell culture media.

Results: Algae extract for this study was prepared from autolysed cells of the green alga Chlamydomonas reinhardtii harvested from a photobioreactor. The nutrient content of the algae extract was evaluated and found to be similar in composition to commercially available yeast extract. Specifically the nutrient content of the algae extract was determined to be 2.99% protein, 9.22% total carbohydrate, and 3.86% free α-amino acid. The effects of algae extract on the growth and metabolism of common laboratory strains of Escherichia coli and Saccharomyces cerevisiae were tested by substituting algae extract for yeast extract in the most common laboratory growth complex media recipes for LB and YPAD media. Complex laboratory media supplemented with algae extract in place of yeast extract showed markedly improved effects on growth and metabolism of common laboratory microorganisms in every test with the exception of ethanol production rate in yeast.

Conclusions: This study showed that algae extract derived from autolysed Chlamydomonas reinhardtii cells is similar, if not superior for certain applications, to commercially available yeast extract in both nutrient content and its effects on the growth and metabolism of E. coli and S. cerevisiae. Based on these results we can conclude that algae extract would serve as a reasonable replacement for yeast extract in most laboratory applications. Bacto^TM yeast extract is valued at US $0.15 to $0.35 per gram, thus if algae extract was sold at a similar cost, it could serve as a high value co-product in an algae-based fuel process. Given the performance of algae extract in this study, we therefore conclude that algae extract could serve as a valuable co-product of algae-based fuels.

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