Effects of the growth medium composition on menaquinone homolog formation in Micrococcus luteus.

Abstract

The menaquinone composition of Micrococcus luteus strains grown in different media was examined. Cells of M. luteus IAM 1056 (type strain) grown in an ordinary complex medium contained MK-8 as the predominant menaquinone. On the other hand, this bacterium produced both MK-8 and MK-8(H2) as major quinones when grown in a chemically defined medium containing glutamate and pyruvate as carbon sources. Unlike the type strain, M. luteus strains IAM 12009 and IAM 12144 had MK-8 (H2) as the major menaquinone, independent of cell growth media. In all strains the total amount of dihydrogenated homologs relative to the total menaquinone content increased more or less in cells grown in the chemically defined medium. Carbon sources and Mgt + concentrations in the growth medium had minor effects on the menaquinone composition of the M. luteus strains. It is now recognized that the analysis of isoprenoid quinones involved in electron transport in the respiratory chain of bacteria provides invaluable criteria for their taxonomy (1, 2,11). Earlier work of Jeffries and associates (7,8) on the menaquinone composition of some aerobic gram-positive cocci was the first to demonstrate the value of respiratory quinones in microbial systematics. They reported that most strains of Micrococcus luteus contained dihydrogenated menaquinones with eight isoprene units (MK-8(H2)) as major isoprenoid quinones, while the strain now designated as the type strain of this species had MK-8 as the major type with significant proportions of MK-8(H2) and the next lower and higher homologs . Similar results were obtained by Yamada et al. (12). Later , Fujii et al. (3) found