Off-line two-dimensional LC–tandem MS of menaquinones from thermophilic bacteria

Abstract

Thermophilic bacteria of four genera in contrast to the commonly used production strains such as Bacillus subtilis, produce homologs other than menaquinone (MK) with seven isoprene units. The number of isoprene units and the configuration of double bonds are essential factors for their biological activity. The goal was to obtain a strain of bacteria that produces a wide range of MK homologs and only all-trans geometrical isomers, which was the strain G. kaustophilus. Using off-line two-dimensional LC–tandem MS in columns with the RP18 phase and the COSMOSIL cholester phase (separation according to the geometric configuration of double bonds) it was shown that thermophilic bacteria grown at different temperatures produce only all-trans isomers of menaquinones from MK-5 (menaquinone with five isoprenyl units) to MK-15 (fifteen isoprenyl units). Therefore, G. kaustophilus appears to be a biotechnologically important strain produces only trans isomers and additionally homologs from 5 to 15 isoprene units.