Free radicals in mercury-resistant bacteria indicate a novel metabolic pathway

A mercury resistant-soil bacterium P. 10.15, identified as a close relative of Pseudomonas veronii, was shown to accumulate a specific compound in the stationary phase of growth. This compound is converted to a long-lived free radical under oxidizing conditions, as registered by its EPR signal at room temperature. The compound was purified by ion-exchange and gel-filtration chromatography and identified by mass spectroscopy, 2D NMR, and EPR as a trisaccharide β-D-GlcpNOH,CH₃-(1→6)-α-D-Glcp- (1→1)-α-D-Glcp, or, in other words, as 6-O-(2-deoxy-2-{N-methyl} hydroxylamino-β-D-glucopyranosyl)-α-α-trehalose, previously discovered in Micrococcus luteus (lysodeikticus) and named lysodektose. It is suggested that the compound is a novel intermediate of a previously unknown basic metabolic pathway of trehalose transformation in bacteria, a potential target for antibacterial drug development.