Calorimetric control of the specific growth rate during fed-batch cultures of Saccharomyces cerevisiae

Accurate control of the specific growth rate (µ) of microorganisms is dependent on the ability to quantify the evolution of biomass reliably in real time. Biomass concentration can be monitored online using various tools and methods, but the obtained signal is often very noisy and unstable, leading to inaccuracies in the estimation of μ. Furthermore, controlling the growth rate is challenging as the process evolves nonlinearly and is subject to unpredictable disturbances originating from the culture’s metabolism. In this work, a novel feedforward-feedback controller logic is presented to counter the problem of noise and oscillations in the control variable and to address the exponential growth dynamics more effectively. The controller was tested on fed-batch cultures of Kluyveromyces marxianus, during which μ was estimated in real time from online biomass concentration measurements obtained with dielectric spectroscopy. It is shown that the specific growth rate can be maintained at different setpoint values with an average root mean square control error of 23 ± 6%.

Download Full-text

Novel Strategy for the Calorimetry-Based Control of Fed-Batch Cultivations of Saccharomyces cerevisiae

Processes ◽

10.3390/pr9040723 ◽

2021 ◽

Vol 9 (4) ◽

pp. 723

Author(s):

Jérémy Kottelat ◽

Brian Freeland ◽

Michal Dabros

Keyword(s):

Saccharomyces Cerevisiae ◽

Growth Rate ◽

Specific Growth Rate ◽

Growth Rates ◽

Specific Growth ◽

Fed Batch ◽

Estimation And Control ◽

Novel Strategy ◽

Specific Growth Rates ◽

Mean Square Errors

Typical controllers for fed-batch cultivations are based on the estimation and control of the specific growth rate in real time. Biocalorimetry allows one to measure a heat signal proportional to the substrate consumed by cells. The derivative of this heat signal is usually used to evaluate the specific growth rate, introducing noise to the resulting estimate. To avoid this, this study investigated a novel controller based directly on the heat signal. Time trajectories of the heat signal setpoint were modelled for different specific growth rates, and the controller was set to follow this dynamic setpoint. The developed controller successfully followed the setpoint during aerobic cultivations of Saccharomyces cerevisiae, preventing the Crabtree effect by maintaining low glucose concentrations. With this new method, fed-batch cultivations of S. cerevisiae could be reliably controlled at specific growth rates between 0.075 h−1 and 0.20 h−1, with average root mean square errors of 15 ± 3%.

Download Full-text

The relationship between nutrient feed rate and specific growth rate in fed batch cultures

European Journal Of Applied Microbiology ◽

10.1007/bf00929159 ◽

1977 ◽

Vol 4 (2) ◽

pp. 87-92 ◽

Cited By ~ 1

Author(s):

R. C. Jones ◽

R. M. Anthony

Keyword(s):

Growth Rate ◽

Specific Growth Rate ◽

Feed Rate ◽

Specific Growth ◽

Fed Batch ◽

Batch Cultures ◽

The Relationship ◽

Nutrient Feed

Download Full-text

Influence of organic acids and organochlorinated insecticides on metabolism of Saccharomyces cerevisiae

Zbornik Matice srpske za prirodne nauke ◽

10.2298/zmspn0508207p ◽

2005 ◽

pp. 207-215 ◽

Cited By ~ 1

Author(s):

Dusanka Pejin ◽

Vesna Vasic

Keyword(s):

Saccharomyces Cerevisiae ◽

Growth Rate ◽

Sugar Beet ◽

Specific Growth Rate ◽

Glycogen Content ◽

Specific Growth ◽

Raw Materials ◽

Stress Factors ◽

Adaptive Mechanism ◽

Ribonucleic Acids

Saccharomyces cerevisiae is exposed to different stress factors during the production: osmotic, temperature, oxidative. The response to these stresses is the adaptive mechanism of cells. The raw materials Saccharomyces cerevisiae is produced from, contain metabolism products of present microorganisms and protective agents used during the growth of sugar beet for example the influence of acetic and butyric acid and organochlorinated insecticides, lindan and heptachlor, on the metabolism of Saccharomyces cerevisiae was investigated and presented in this work. The mentioned compounds affect negatively the specific growth rate, yield, content of proteins, phosphorus, total ribonucleic acids. These compounds influence the increase of trechalose and glycogen content in the Saccharomyces cerevisiae cells.

Download Full-text

Anaplerotic reactions active during growth of Saccharomyces cerevisiae on glycerol

FEMS Yeast Research ◽

10.1093/femsyr/foz086 ◽

2019 ◽

Vol 20 (1) ◽

Cited By ~ 1

Author(s):

Joeline Xiberras ◽

Mathias Klein ◽

Celina Prosch ◽

Zahabiya Malubhoy ◽

Elke Nevoigt

Keyword(s):

Saccharomyces Cerevisiae ◽

Growth Rate ◽

Specific Growth Rate ◽

Pyruvate Carboxylase ◽

Reference Strain ◽

Specific Growth ◽

Glyoxylate Cycle ◽

Maximum Specific Growth Rate ◽

The Glyoxylate Cycle ◽

Anaplerotic Reactions

ABSTRACT Anaplerotic reactions replenish TCA cycle intermediates during growth. In Saccharomyces cerevisiae, pyruvate carboxylase and the glyoxylate cycle have been experimentally identified to be the main anaplerotic routes during growth on glucose (C6) and ethanol (C2), respectively. The current study investigates the importance of the two isoenzymes of pyruvate carboxylase (PYC1 and PYC2) and one of the key enzymes of the glyoxylate cycle (ICL1) for growth on glycerol (C3) as a sole carbon source. As the wild-type strains of the CEN.PK family are unable to grow in pure synthetic glycerol medium, a reverse engineered derivative showing a maximum specific growth rate of 0.14 h−1 was used as the reference strain. While the deletion of PYC1 reduced the maximum specific growth rate by about 38%, the deletion of PYC2 had no significant impact, neither in the reference strain nor in the pyc1Δ mutant. The deletion of ICL1 only marginally reduced growth of the reference strain but further decreased the growth rate of the pyc1 deletion strain by 20%. Interestingly, the triple deletion (pyc1Δ pyc2Δ icl1Δ) did not show any growth. Therefore, both the pyruvate carboxylase and the glyoxylate cycle are involved in anaplerosis during growth on glycerol.

Download Full-text