Yeast cell factory: Fishing for the best one or engineering it?

Editorial. When today scientists and bioprocess engineers look at a Microbial Cell Factory for the production of a protein or a metabolite of commercial or research interest, they think at the microorganism of choice first from a (i) molecular, then from a (ii) metabolic and finally from a (iii) process point of view. Analyses and manipulations of the pathway(s) involved in the synthesis of the desired product and how this pathway(s) interacts with the overall cell functions and activities are indeed steps required to obtain high yield of the product (g of compound per g of substrate), high production (g/l) and high productivity (g/l/h). Conceptually, the whole set of biochemical reactions that take place in the microbial cell factory should be considered. This is valid for processes involving natural and/or recombinant products in wild type and/or engineered hosts