Résumé
Several recent studies have shown the feasibility of producing both hydrogen and biolipids by coupling dark hydrogen fermentation of organic waste with lipid accumulation by microalgal heterotrophy [1]. Such combination allows the use of dark fermentation by-products (i.e. volatile fatty acids such as acetate, butyrate and lactate) as a low cost substrate to sustain microalgal heterotrophic growth. Nevertheless, little is known about the influence of mixed carbon sources on microalgal growth and some of dark fermentation by-products may act as growth inhibitor (e.g. butyrate) [2]. The objective of this study is to characterize the consumption of acetate, butyrate and lactate as single or mixed carbon sources by two lipid producing heterotrophic microalgae, Chlorella sorokiniana and Auxenochlorella protothecoides, using a kinetic modeling approach. Results will give new insights on microalgal physiology for optimizing the coupling of H2 producing dark fermentation and microalgal lipid production.