Fermentation of Saccharomyces cerevisiae - Combining kinetic modeling and optimization techniques points out avenues to effective process design.

A combined experimental/theoretical approach is presented, for improving the predictability of Saccharomyces cerevisiae fermentations. In particular, a mathematical model was developed explicitly taking into account the main mechanisms of the fermentation process, allowing for continuous computation of key process variables, including the biomass concentration and the respiratory quotient (RQ). For model calibration and experimental validation, batch and fed-batch fermentations were carried out.

Monitoring cellular stress responses using integrated high-frequency impedance spectroscopy and time-resolved ELISA.

We have developed a lab-on-a-chip system for continuous and non-invasive monitoring of microfluidic cell cultures using integrated high-frequency contactless impedance spectroscopy. Electrically insulated microfabricated interdigitated electrode structures were embedded into four individually addressable microchambers to reliably and reproducibly detect cell-substrate interactions, cell viability and metabolic activity. While silicon nitride passivated sensor substrates provided a homogeneous cell culture surface that minimized cell orientation along interdigitated electrode structures, the application of high-frequency AC fields reduced the impact of the 300 nm thick passivation layer on sensor sensitivity.