The role of microbe-matrix interactions in dairy starter culture functionality

Lactococcus lactis is one of the lactic acid bacteria species used for fermentation of cheese, quark and buttermilk and determines taste, texture, and the shelf life of a product. Surface properties of microorganisms are determined by the molecular composition of the cell wall and influence the interactions of microbes with their environment. This study was focused on a better understanding of molecular mechanisms involved in interactions between L. lactis and the matrix of fermented dairy products. The results suggest that cell surface alteration should allow modifying starter culture functionality and developing new concepts in formulating fermented products with an altered texture. Another example of a new concept for the application of lactic acid bacteria could be clean label stabilization of oil-in-water emulsions with L. lactis strains via the Pickering stabilization mechanism. In this study we have shown that bacterial cell aggregation is of importance in this respect as it improves the stabilization of oil droplets. In yet another example starter cells could be employed as structure elements such as inert fillers or as structure breakers in fermented food. While the knowledge of the molecular mechanisms determining L. lactis cell surface properties and, subsequently, the microbe-matrix interactions are far from complete, this work and future research on the microbe-matrix interactions certainly holds a potential for improving current manufacturing processes and developing novel products.