Petite-negative mutants of Saccharomyces cerevisiae

A series of yeast mutants has been isolated with the inability to grow on fermentable carbon sources whilst growing normally on ethanol media. One of the mutants, namely MC16/206 lacks pyruvate decarboxylase activity and does not grow on glucose at 37 degrees C but grows on both ethanol and glucose at 27 degrees C. In this strain rho- petites are non-viable.