Regulation and control of acid production in lactobacilli: (LABACID)

PROJECT LABACID: One of the most important principles for food preservation and safety is acidity. In fermented foods, production of lactic acid contributes significantly to the safety against food pathogens. Knowledge about lactic acid production is ther efore of paramount importance for the food industry. Despite large efforts in the research of different aspects of lactic acid bacteria world-wide, there is surprisingly little known about the primary metabolism giving lactic acid, i.e. glycolysis. This is especially true for lactobacilli involved in meat and vegetable fermentation, i.e. Lactobacillus sakei and L. plantarum. Some of the questions are: What are the rate-limiting steps? How are the genes and enzymes involved in the metabolism regulated? How d oes external factors affect gene expression and the metabolism? This project will use a combined physiological/gene expression analysis approach to address these questions. Studies of glycolytic flux under many different conditions will give a general pic ture of the metabolism. Expression of key glycolytic genes will be analysed using quantitative PCR/array methods. Engineered strains with modified levels of glycolytic enzymes will be constructed to identify controlling steps in the metabolism. This combi ned approach will give a detailed picture of the metabolism and give opportunities to optimise acid production.