Abstract
We explored the use of Raman spectroscopy to detect organic osmotic solutes as biomarkers in the moderately halophilic heterotrophic bacterium grown in complex medium (accumulation of glycine betaine) and in defined medium with glucose as carbon source (biosynthesis of ectoine), and in the anoxygenic phototrophic known to synthesize glycine betaine in combination with minor amounts of trehalose and -alpha-carbamoyl glutamineamide. We tested different methods of preparation of the material: lyophilization, two-phase extraction of water-soluble molecules, and perchlorate extraction.
Raman signals of glycine betaine and ectoine were detected; perchlorate extraction followed by desalting the extract on an ion retardation column gave the best results. Lyophilized cells of showed strong signals of carotenoid pigments, and glycine betaine could be detected only after perchlorate extraction and desalting.
The data presented show that Raman spectroscopy is a suitable tool to assess the mode of osmotic adaptation used by halophilic microorganisms.