A DIFFERENTIAL AND DIAGNOSTIC PLATING METHOD FOR POPULATION STUDIES OF RESPIRATION DEFICIENCY IN YEAST

Abstract

A differential plating method has been devised for studies of mixed populations of respiration sufficient (AER) and deficient (aer) yeast. It employs a control medium enabling both AER and aer cells to form colonies and a selective medium enabling only AER cells to form colonies. Model experiments with mixtures of AER and aer yeasts in various proportions indicated good correspondence between calculated and found population percentage over a wide range of compositions, even at low concentrations of AER cells in a predominantly aer population (where the differential count is large). The precision of the differential method becomes poorer as one approaches the other population extreme of low concentration of aer cells in a predominantly AER population (where the differential count is small). The selective medium may be applied qualitatively to the identification and isolation of a few AER cells in a predominantly aer population.