Oscillations in continuous cultures of budding yeast: A segregated parameter analysis

Abstract

Sustained oscillations have been observed in continuous cultures of Saccharomyces cerevisiae. These oscillations appear spontaneously under aerobic conditions and may constitute a severe limitation for process control. We have found that oscillations arise only in a well defined range of dilution rates and dissolved oxygen values. The period of the oscillations is related, but not equal, to the mass doubling time, and shows a relation ship with both the parent cells and daughter cells generation times. At high dilution rates two oscillatory regimens, with different periods, are observed. The analysis of the budding index shows a marked degree of synchronization of the culture, however significant differences, both in phase and in amplitude, are ob served if the budding index of parent cells and of daughter cells are considered separately. The complex changes of the cell population are clearly demonstrated by the continuous and periodic modification of both cell volume distributions and protein distributions. Ethanol is always accumulated before the drop of dissolved oxygen concentration and one of the peaks of budding index. We propose a model that explains the insurgence of these oscillation as a consequence of changes in cell cycle parameters due to alternate growth in glucose and in ethanol.

Interaction of the GTS1 gene product with glyceraldehyde‐ 3‐phosphate dehydrogenase 1 required for the maintenance of the metabolic oscillations of the yeast Saccharomyces cerevisiae

“…Synthetic oligonucleotides for 5¢ and 3¢ primers, 3 and 4 for TDH1, Table 1. List of synthetic oligonucleotides used for primers (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13) or probes (14,15) in this experiment.…”

Periodic and chaotic solutions for a model of a bioreactor with cell recycle

“…Porro (4) for instance examined the occurrence of spontaneous oscillations in the continuous cultures of the budding yeast, S. cerevisiae, and found that periodic behavior is strongly dependent on the dissolved oxygen levels.…”

Oscillatory, stochastic and chaotic growth rate fluctuations in permittistatically controlled yeast cultures

“…Continuous culture methods are frequently used for studying 'steady-state' microbial growth, although fluctuations in NADH levels and the respiration rate of bacteria (Degn and Harrison, 1969;Harrison, 1970), and of various metabolic intermediates and fermentation parameters in cultures of yeast (Satroutdinov et al, 1992;612 et al, 1993) have been reported in these systems, and numerous studies have shown that the restricted (Rieger et al, 1983;Sonnleitner and Kappeli, 1986) respiro-fermentative metabolism of baker's yeast is capable of oscillations (Porro et al, 1988;Richard et al, 1994) and indeed chaos (Markus et al, 1985). Oscillations in the biomass content of yeast in a chemostat have been reported (Striissle et al, 1988(Striissle et al, , 1989Chen et al, 199Oa,b;Munch et al, 1992;Auberson et al, 1993), although of course the overall growth rate of such cultures remains constant, whilst (possibly entrained) growth rate oscillations were also recently observed in fedbatch cultures of a recombinant strain of Escherichiu co/i (Ye et al, 1994).…”