CD Laboratory for Growth-decoupled protein production in yeast

Recombinant proteins are often produced using biotechnologically modified yeasts, whereby the protein yield increases with yeast growth. This CD Laboratory is now looking for ways to decouple protein synthesis and yeast growth.

As protein synthesis and secretion correlate with yeast growth, the biomass must grow continuously to enable efficient product formation. However, the high biomass concentrations achieved can lead to technical problems during the large-scale production of proteins. A process that allows efficient production of recombinant proteins using relatively low concentrations of biomass would therefore be desirable, but is not yet technically feasible.

The rate of yeast growth is primarily regulated by the supply of nutrients. In order to be able to produce proteins in a predictable manner even when yeast cultures are growing slowly, knowledge of their living conditions and cell regulation mechanisms under extreme nutrient deficiency must be deepened. To this end, the yeast Pichia pastoris is to be cultivated in retentostat cultures. Retentostat cultures are characterised by the fact that the nutrient medium is removed from the biomass reactor until the amount of used nutrient medium just covers the nutritional requirements of the existing biomass, but does not stimulate further growth. In this system, all the characteristic metabolic properties of the yeast cell are analysed in order to draw conclusions about which metabolic pathways are active at which point in the cycle.

This fundamental knowledge forms the scientific basis for the prediction and development of novel genetically modified yeasts, so-called cell engineering strategies, which are able to decouple protein synthesis and secretion from growth. The genetically modified strains are then validated by cultivating them under controlled conditions at very low specific growth rates. The aim is to prove that protein synthesis and secretion have indeed been decoupled from biomass formation.

The knowledge of growth and secretion processes established through the research of this CD Laboratory opens up possibilities for the development of optimised production platforms and processes in the future.