PRODUCTION OF HYDROXYECTOINE - HIGH CELL-DENSITY CULTIVATION AND OSMOTIC DOWNSHOCK OF MARINOCOCCUS STRAIN M52

This study reports the mass-cultivation of a Gram-positive halophilic microorganism for the biotechnological production of the compatible solute and enzyme protectant hydroxyectoine. A high cell-density cultivation of the hydroxyectoine producer strain M52 (Marinococcus sp.) was performed using an exponential fed-batch strategy with medium exchange. Grown on a complex glycine betaine-free medium containing 10% (w/v) salt, 56 g cell dry weight per 1 were produced as compared to only 6 g l(-1) in a batch process. The desired product hydroxyectoine accounted for 13.5% of the cellular dry weight. As strain M52 tolerates extreme changes of the surrounding osmolarity, the extraction and purification of hydroxyectoine could be simplified by washing the dense culture of M52 prior to cell harvest using demineralized water (osmotic downshock). Hydroxyectoine was then easily extracted from the washed and 'desalted' cell material by Soxhlet extraction with methanol.