SIZING AND COUNTING OF SACCHAROMYCES-CEREVISIAE FLOC POPULATIONS BY IMAGE-ANALYSIS, USING AN AUTOMATICALLY CALCULATED THRESHOLD

A standardized image analysis method has been developed permitting det ermination of the number of yeast flocs and their size distribution. T he method includes image grabbing, image enhancement, automatic determ ination of the appropriate threshold, curve fitting of the area histog ram, determination of the mean single flee area and its standard devia tion, and flee counting. The extension of the method to other applicat ions is immediate and straightforward. Two Saccharomyces cerevisiae fl ee populations (with ages of 48 and 72 h) were analyzed. The results s howed a variation around the mean of 9%-12% for the single flee mean a rea, 6%-7% for the number of single flocs, and 5%-6% for the total num ber of flocs. Aggregates of two flocs (doublets) and three flocs (trip lets) were enumerated. The correctness of the method was checked by an alyzing the parameters of interest as a function of the threshold. The constant correlation between the parameters and the threshold showed the validity and consistency of the method. (C) 1996 John Wiley & Sons , Inc.