(46c) Analysis of Methods for Description of Yeast Cell Morphology

At the present state of the art of technology, the knowledge of characteristics of microbial cell morphology is necessary to conduct many biotechnological processes. For this reason, studies are performed on the modelling of cell growth depending on culture conditions, growth kinetics of specified products produced by microorganisms, or cell disruption kinetics. The paper gives a comparison of description of yeast cells by means of a laser diffraction spectrophotometer and digital microscopic image analysis. Studies were carried out for baker's yeast Saccharomyces cerevisiae. Using a laser analysis, particle size distribution was prepared by the Fraunhofer method. To determine geometric parameters of cells a computer program was applied. An automatic detection and measurement of cells were used. A minimum and maximum cell sizes, their equivalent diameter, surface areas and shape factors were measured. The curves of size analysis obtained by the two methods were compared with results obtained from manual measurements made for basic microscopic images. Basing on mathematical descriptions, good agreement of results of the measurements obtained especially as a result of microscopic image analysis was achieved. Using both the automatic detection and laser analysis, particles bigger than 0.012 mm were detected. This is a result of grouping cells or partial overlapping of their projections. The application of the methods described depending on admissible measurement errors was presented.