sentence: Cells were grown for 2 – 3 days under aerobic conditions at 30 ° C in YP ( 0.3 % yeast extract and 0.3 % peptone ) , YPS ( YP supplemented with 2 mM CaCl and 2 mM MgSO ) , or PYCa ( 0.1 % yeast extract , 1.5 % peptone , 0.5 % CaCl , 0.1 % glucose ) to an OD of ~ 1.0 .