PhD project title: Lactic Acid Bacteria for Efficient Delivery of Vitamin K2
Duration: Sept 2016 - Sept 2020
Vitamin K is a fat-soluble vitamin that is essential to human health. It acts as an enzyme co-factor required for the activation of proteins involved in vital physiological processes including haemostasis, calcium metabolism and cell growth regulation. Vitamin K exists in two forms: vitamin K1 (phylloquinone) derived from plants and vitamin K2 (menaquinons) of bacterial origin. Intake of vitamin K2 was recently reported to be associated with a reduced risk of coronary heart disease. Optimization of vitamin K2 production and its delivery to the human host have not yet been explored extensively. Lactic acid bacteria (LAB) are key players in various food fermentation processes. Some LAB strains produce vitamin K2 in the bacterial cell membrane as electron carriers in the respiratory electron transport chain. These properties make LAB ideal vehicles for vitamin K2 fortification. Meanwhile, emerging evidence of extracellular membrane vesicle production in Gram-positive bacteria including LAB, potentially provides a novel method to improve the delivery of the lipid soluble vitamin K2 to the human body. In this study we focus on the exploration and exploitation of high vitamin K2 producing LAB which secrete membrane vesicles, with the aim to obtain generic knowledge of the membrane vesicle production process and to elucidate factors that affect vitamin K2 loading.