I. Cytochrome oscillations in continuous culture: Action of chloramphenicol on Saccharomyces carlsbergensis and Candida utilis

Oscillations in the A, B and C group cytochromes of Saccharomyces carsbergensis and Candida utilis have been observed in continuous culture following the addition and removal of chloramphenicol. With S. carlsbergensis reproduction of these oscillations proved difficult due to the fermentative nature of the yeast. With C. utilis at D = 0.1 h⁻¹ the oscillations in teh A group cytochromes were statistically significant and 3–6 times the standard deviation observed in steady sate. The oscillations provide evidence of a feedback loop controlling cytochrome synthesis and have a period of the same order of that predicted by Goodwin for the protein (enzyme) component of his model (viz. 6–8 h). With C. utilis the period of these oscillations was a function of the growth rate varying from approx. 10 h at a growth rate of 0.1 h⁻¹ (mean generation time 6.9 h) to 3 h at a growth rate of 0.3 h⁻¹ (mean generation time 2.3 h).