‘Evolution’ often optimises one trait at the cost of another. This project will reveal how such trade-offs affect industrial fermentations, investigating the role of the enzymes involved in growth, acidification, and flavour and texture development in dairy production.

In engineering and economics trade-offs are well known. Similarly, evolutionary trade-offs in microbial cells are defined as the optimization of one trait at the cost of another. For instance if a cells puts lots of energy into the production of costly molecules like exo-polysaccharides, little energy is available for cell growth.

This project focuses on the influence of trade-offs on industrial fermentations. We will investigate the role for key enzymes in dairy fermentations, including enzymes involved in growth, (post-)acidification, flavour- and texture formation. Industrially relevant parameters will be investigated including temperature, salt, starvation and pH stress. These conditions change rapidly throughout cheese manufacturing, and we will investigate how these changes influence functionality of the starter culture in the fermented dairy product. The results of this project are designed to allow us to develop new starter cultures, shorten lag-phases, increase flavour formation, and shorten cheese-ripening times and improve the robustness of the fermentation process.

Main deliverables

• Proteome turnover in L. lactis under industrial relevant conditions.
• Enzymatic activity decay data on at least 10 flavour- and growth-related enzymes at industrially relevant conditions.
• Impact of environmental transitions on heterogeneity, outgrowth and fermentation times in milk.
• Modulation of the catalytic capacity of a starter culture.
• Extended metabolic model to identify trade-offs based on data generated in the deliverables above.
• Alteration of starter functionalities (in whey, milk and cheese) by exploiting trade-offs.

Project info

• Project leader: Dr Herwig Bachmann
• Time Frame: 2016 – 2020
• Project code: 16MF01