Production of menaquinones by lactic acid bacteria

Lactic acid bacteria were examined for their ability to produce quinone com pounds, which may include dietary sources of menaquinones. Isoprenyl quinon es in bacterial cells grown in a synthetic medium were extracted and analyz ed by thin layer chromatography. Lactococcus lactis ssp. cremoris (three st rains), Lactococcus lactis ssp. lactis (two strains), and Leuconostoc lacti s were selected as high producers of quinone that synthesized more than 230 nmol of quinones/g of dried cells. The quinones were presumed to be menaqu inone-7 to -10 by high performance liquid chromatography. Precise molecular weights were determined by mass spectrometry for Lactococcus lactis ssp. c remoris YIT 2011 and Leuconostoc lactis YIT 3001 and identified as menaquin one-8 and -9 for the former and menaquinone-9 and -10 for the latter. Those strains, when grown either in reconstituted nonfat dry milk or a soymilk m edium, produced a beneficial quantity for dietary supplement (i.e., 29 to 1 23 mu g of menaquinones/L of the fermented medium).