A spontaneous flocculation mutant (Cgflo1) was obtained from Candida glabrata. Flocculation of Cgflo1 was dependent on divalent cations such as Ca2+ and Me2+ and was inhibited by galactose. Cgflo1 is believed to be a useful strain for bioethanol production based on its flocculation ability at higher temperatures. (c) 2008, The Society for Biotechnology, Japan. All rights reserved.