Find any reference for YBGM or similar medium that is used for lacZ expression
in yeast. You need near neutral pH to detect xgal-->blue.
RELATED QUESTION: Anyone know of a yeast color indicator that does not need
neutral pH? -----Thanks
Sanford Silverman >Opinions expressed here are my own<
sandy at pt.cyanamid.com, silvermans at pt.cyanamid.com "Yeast is Best"