[Age structure of methanol-assimilating Candida boidinii cells]

A population of Candida boidinii was grown under the chemostat conditions at a dilution rate of 0.14-0.20 h-1 in a mineral medium with methanol as a sole source of carbon and energy. Its age structure was analysed taking account of the reproductive age (the number of cycles) and the cyclic age of the cells (the phase of a cell cycle). Four morphological phases of the cycle, namely, one phase of preparation for budding and three successive budding phases, were compared with the phases G1, S, G2 and M. In terms of their reproductive age, the cells can be arranged as follows: (1) cells that formed no buds at all, 43 +/- 5%; (2) cells after one cycle of budding, 28 +/- 4%; (3) cells from which two and more daughter cells have separated, 29 +/- 4%. The age structure of an yeast population must be analysed when it is necessary to estimate its physiological heterogeneity or to elaborate the cultivation of microorganisms involving the control over the age structure of the population.