Flocculation of wall-deficient cells of Chlamydomonas reinhardtii mutant cw15 by calcium and methanol

► Wall-deficient cells of C. reinhardtii mutant cw15 flocculate in CaCl2 at pH 8.4. ► Wildtype cells do not flocculate similarly. ► Methanol facilitates calcium-induced flocculation of cw15. ► A flocculation inhibitor is produced or a facilitator is consumed during cw15 growth.