The aim of this investigation was to perform an extensive screening using HPLC and I3C-NMR spectroscopy to disclose the spectrum of osmolytes produced by aerobic heterotrophic and anoxygenic phototrophic eubacteria. The most predominant solutes detected within a wide range of marine and halophilic micro-organisms were two recently discovered tetrahydropyrimidines ectoine and hydroxyectoine, which were synthesized in response to osmotic stress.

A new family, the Hafomonadaceae, has recently been proposed for members of the genera Deleya and Halornonas. The three strains investigated, Deleya haiuphila, Halomonas elongata and Flavobacterium halmephilum (reclassified as H. hahophila), are aerobic heterotrophic micro-organisms exhibiting an extreme salt tolerance. The major organic osmoregulatory solutes of these organisms were examined using 3C-nuclear magnetic resonance spectroscopy. The relative proportions of the solutes varied with respect to salt concentration, temperature and carbon source. The recently described amino acid ectoine was found to be a dominant solute. For the first time it could be shown for halophilic eubacteria that the intracellular concentration of solutes is sufficient to balance the osmotic pressure of the medium. Thus, there is no need to postulate a hypo-osmotic cytoplasm.

A new species of the genus Nocardiopsis, for which we propose the name Nocardiopsis lucentensis sp. nov. (type strain, strain DSM 44048), was isolated from a salt marsh soil sample near Alicante, Spain. Whole-cell hydrolysates contain the meso isomer of diaminopimelic acid and no characteristic sugar; thus, the cell wall composition is type 111. Menaquinone MK-lO(H,) is the major menaquinone, and the phospholipid type is type PI11 (phosphatidylcholine present). Spore chains are rectiflexibilis, and in the early stages of sporulation zig-zag-shaped aerial hyphae are observed. This microorganism produces compatible solutes of the ectoine type and is characterized by a yellowish to yellowish brown substrate mycelium and a white aerial mycelium. This organism exhibits only 40 to 50% DNA relatedness to other Nocardiopsis spp.

In the first column, the subheading for the third group of organisms should read Proteobacteria (y-subclass). p. 1632, column 2, line 12: for position 3 read position 5. p. 1634, column 1, line 2 : for glycosylglycerin read glycosylglycerol. p. 1635, column 2, line 16: for Firmacutes read Firmicutes.

No abstract