Figure 1

The assembly of a multi-trait yeast cell factory. The future yeast cell factory strains will require combinations of several traits, each of which will be encoded by a specific genetic module (depicted by strings of arrows) engineered using the state-of-the-art synthetic biology approaches, such as marker-free multiplex genome editing and orthogonal promoter libraries. In the future, individual “ready-to-use” modules should become available for fast transfer of the desired traits to the recipient strain in any combination. The order in which the respective modules are introduced will depend upon the specific conditions/requirements. Left Depending on the biotechnological process, different robustness traits will have to be introduced into the starting strain (e.g. tolerance to extreme pH, osmotic stress, organic acids or other toxic substances). Following the isolation of strains with superior performance with regard to specific traits (depicted by different colours), causal genes can be identified by polygenic trait analysis and/or by bioinformatics methods, as described in the text. Centre Optimization of the strains for efficient utilization of renewable feedstocks is another important aspect in engineering multi-trait yeast cell factories. Utilization of pentoses, especially xylose, and in the future also of lignin, will enable more cost-effective production of biochemicals. The next generation of yeast cell factories will be capable of consolidated bioprocessing (CBP), as described in the text. Right The biosynthesis pathway for the desired product could consist of a number of endogenous and/or heterologous genes. These genes will be combined with standard modules that will provide common building blocks or contribute to cofactor balance (The image in “B” is a detail from “Champs DSC01354" by Daplaza, licensed under CC BY-SA 2.5).