Abstract
BackgroundVitamin K2 (menaquinone, MK-n) is a lipid-soluble vitamin that functions as a carboxylase co-factor for maturation of proteins involved in many vital physiological processes in humans. Notably, long-chain vitamin K2 is produced by bacteria, including some species and strains belonging to the group of lactic acid bacteria (LAB) that play important roles in food fermentation processes. This study was performed to gain insights into the natural long-chain vitamin K2 production capacity of LAB and the factors influencing vitamin K2 production during cultivation, providing a basis for biotechnological production of vitamin K2 and in situ fortification of this vitamin in food products.ResultsWe observed that six selected Lactococcus lactis strains produced MK-5 to MK-10, with MK-8 and MK-9 as the major MK variant. Significant diversities between strains were observed in terms of specific concentrations and titres of vitamin K2. L. lactis ssp. cremoris MG1363 was selected for more detailed studies of the impact of selected carbon sources tested under different growth conditions [i.e. static fermentation (oxygen absent, heme absent); aerobic fermentation (oxygen present, heme absent) and aerobic respiration (oxygen present, heme present)] on vitamin K2 production in M17 media. Aerobic fermentation with fructose as a carbon source resulted in the highest specific concentration of vitamin K2: 3.7-fold increase compared to static fermentation with glucose, whereas aerobic respiration with trehalose resulted in the highest titre: 5.2-fold increase compared to static fermentation with glucose. When the same strain was applied to quark fermentation, we consistently observed that altered carbon source (fructose) and aerobic cultivation of the pre-culture resulted in efficient vitamin K2 fortification in the quark product.ConclusionsWith this study we demonstrate that certain LAB strains can be employed for efficient production of long-chain vitamin K2. Strain selection and optimisation of growth conditions offer a viable strategy towards natural vitamin K2 enrichment of fermented foods, and to improved biotechnological vitamin K2 production processes.
Highlights
Vitamin K is a fat-soluble vitamin that is essential for human health [1]
Strain diversity in vitamin K2 production To reveal the natural capacity of vitamin K2 production in different lactic acid bacteria (LAB) strains, we examined MK forms and levels in strains of L. lactis ssp. lactis, L. lactis ssp. cremoris and Lc. mesenteroides (Fig. 1)
Among the L. lactis strains, a large diversity of vitamin K2 producing capacity was demonstrated by the specific concentrations: L. lactis ssp. cremoris MG1363 and L. lactis ssp. lactis FM03 produced the highest amount of vitamin K2, reaching 125 nmol/g cell dry weight (CDW); L. lactis ssp. cremoris DSM20481 produced the lowest amount, 13 nmol/g CDW (Fig. 1a)
Summary
Vitamin K is a fat-soluble vitamin that is essential for human health [1] It functions as an enzyme cofactor for γ-carboxylation of glutamate (Gla) residues in Gla-proteins, which play key roles in a number of vital physiological processes including haemostasis, calcium and bone metabolism, as well as cell growth regulation [1, 2]. The main dietary sources of long-chain MKs are fermented foods [3, 4]. Vitamin K2 (menaquinone, MK-n) is a lipid-soluble vitamin that functions as a carboxylase co-factor for maturation of proteins involved in many vital physiological processes in humans. Long-chain vitamin K2 is produced by bacteria, including some species and strains belonging to the group of lactic acid bacteria (LAB) that play important roles in food fermentation processes. This study was performed to gain insights into the natural long-chain vitamin K2 production capacity of LAB and the factors influencing vitamin K2 production during cultivation, providing a basis for biotechnological production of vitamin K2 and in situ fortification of this vitamin in food products
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
