S182: Engineering Lactococcus lactis for food and health

Lactococcus lactis is an industrially relevant microorganism used worldwide in food fermentations, and is one of the best characterized species of the lactic acid bacteria. The technological breakthroughs in functional genomics, combined with a “generally recognized as safe” (GRAS) status, a relatively simple metabolism, a small genome, and rapid growth, make L. lactis an ideal host for the production of valuable ingredients for the industry (food and pharmaceutical). However, a deep understanding of the metabolic network as well as of the interdependence relationships among the different steps is essential to a rational design of strains. To achieve this goal, genome-wide techniques such as transcriptome analysis need to be complemented with the analysis of the ensemble of metabolites in the cell, desirably as a function of time. Nuclear magnetic resonance (NMR) can provide unique information on intracellular metabolites in a non-invasive way. The application of this technique enables to monitor substrate consumption and end-product formation, as well as to follow changes in the concentration of intracellular metabolites in real time and non-invasively in microbial cell suspensions. Examples of the application of in vivo NMR to elucidate the regulation of sugar metabolism in first generation L. lactis engineered strains will be presented. Guidelines provided by this analysis were used as a foundation to develop L. lactis strains with added value for food and health.