Evolutionary trade-offs in dairy fermentation: Environmental modulation of lactococcal enzyme activities and its impact on cheese.

The production of cheese encompasses many different conditions and depends on specific desired traits of the starter bacteria used for production, such as fast acidification rates, robustness or yield of specific metabolites. The starter bacteria need to carry out these functions in the dynamic environment of cheese and thereby face constraints and limitations. This project intends to decipher trade-offs that occur in these bacterial properties, which means that the optimization of one property can only occur at the cost of another. To some extent, these trade-offs may be explained from a protein economy perspective, where nutrient and energy resource allocation in cells is constrained by their proteome synthesis and adjustment. This project in particular focuses on the influence of trade-offs on key enzymes of dairy fermentation that are involved in growth, (post-) acidification, flavor- and texture formation. We will investigate how starter functionality is affected through various culturing and fermentation conditions, especially during the ripening of cheese. This will include the experimental investigation in environments that closely resemble industrial conditions such as our high-throughput cheese model. From an application point of view, a better understanding of the constraints that shape trade-offs in industrially-relevant bacterial properties will open new avenues to modify cheese-production process conditions to modulate flavour formation or skew flavour formation in a certain direction. Such adjustments can influence product properties such as flavor and texture, e.g. increased flavor formation and shorter ripening time, or shorter starter lag phase and/or enhanced processing robustness.