Efficient Extraction of Starch from Microalgae Using Ultrasonic Homogenizer and Its Conversion into Ethanol by Simultaneous Saccharification and Fermentation

To utilize starch and protein contained in microalgae as carbon and nitrogen sources for ethanol production, an extraction method, i.e. ultrasonic treatment using a homogenizer, and simultaneous saccharification and fermentation (SSF) of extracted microalgae solution were studied using Chlamydomonas fasciata Ettl 437. 30 min of ultrasonic treatment gave the maximum extraction ratio of starch contained in microalgae, i.e. 93.8%, that corresponded to 0.408 g-starch/g-dry microalgae. SSF of the extracted solution obtained from ultrasonic treated microalgae at 30 min by glutase-AN and Saccahromyces cerevisiae AM12 provided 0.194 and 0.168 g-ethanol/g-dry microalgae with and without yeast extract, respectively, corresponding to 79.5 and 68.8% of theoretical ethanol yield.