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Brewing Change: Dark Fermentation of Photosynthetic Microalgae

Kuehnle, Adelheid, Schurr, Robert
Industrial biotechnology 2019 v.15 no.1 pp. 3-8
active ingredients, beers, biotechnology, brewing, consumer acceptance, fermentation, hydrocarbons, manufacturing, markets, microalgae, organic acids and salts, personal care products, photosynthesis, photosynthetic algae, raw materials, stainless steel, sugars, tanks, yeasts
Microalgae are commonly viewed as being photosynthetic, requiring light for growth. However, certain algae can grow much more efficiently in the dark, in enclosed tanks, when provided hydrocarbons like sugar or organic acids. This facultative ability of some photosynthetic algae to switch to a dark aerobic fermentation process results in bioactive or functional compounds being produced in a fraction of the time and using a fraction of the water otherwise required for conventional photosynthetic production. Stainless steel tanks—like those used for yeast culture in beer breweries—can be coupled with sophisticated control systems and strategies for the precision cultivation of specialty microalgae cells. The “craft brewing” approach has proven a commercial success for a few species and target compounds. Extending this approach to additional photosynthetic algal species could provide advantages over current practices and sources of raw materials. This overview describes our company's use of dark aerobic fermentation for the manufacture of whole-cell and extracted raw material from carotenogenic microalgae. One outcome is an industrial process adopting more resource-friendly practices required for consumer acceptance in certain market applications. A second outcome is a path to supplying sustainable products to replace chemically synthesized products in markets where it appears reasonable to do so. In addition, methods are being discovered for the production of innovative compounds for use in personal care products and other formulations. Broad application of the technology will succeed through engagement with corporate partners committed to sustainable production and products.