Identification of Nδ-acetylornithine as a novel osmolyte in some Gram-positive halophilic eubacteria

In the course of a screening programme for novel natural substances acting as compatible solutes, an unusual amino acid derivative was detected in several halophilic Gram-positive eubacteria. The compound was isolated and subsequently identified as Nδ-acetylornithine using spectroscopic (NMR, MS) and chromatographic methods. So far, Nδ-acetylornithine has only been described as an excretion product of some bacteria under certain growth conditions. This report describes, for the first time, its intracellular accumulation and use as a compatible solute in halophilic/halotolerant eubacteria.