Abstract

Microalgae can be used as both food and a source of bioactive compounds, such as oils, vitamins and biosurfactants. An important factor contributing to the production costs of bioactive compounds, such as biosurfactants, is the carbon source. One way to decrease production costs is by reducing carbon without a concomitant reduction in productivity. Biosurfactants have a wide range of industrial applications, particularly in the food industry, where they are used as emulsifiers and thickeners. We have investigated the use of cyanobacteria Arthrospira sp. LEB 18 and Synechococcus nidulans LEB 25 and of chlorophytes Chlorella minutissima LEB 108, Chlorella vulgaris LEB 106 and Chlorella homosphaera for the production of biosurfactants using autotrophic and mixotrophic cultivation. The strains were grown in Erlenmeyer photobioreactors containing appropriate media with NaHCO₃ as the autotrophic carbon source and glucose or molasses for mixotrophic growth. The results obtained demonstrate the potential of organic carbon sources to stimulate both the growth of microorganisms and biosurfactant production. Furthermore, the data highlight the potential of using molasse, a low-cost byproduct, as an organic substrate for microalgae cultivation.

Key words: Bicarbonate, biosurfactants, glucose, molasse, superficial tension.