Erythritol biosynthesis from glycerol by Yarrowia lipolytica yeast: effect of osmotic pressure

The aim of this study was to examine the impact of osmotic pressure, regulated by an addition of different NaCl concentrations, on the production parameters and activity of the enzymes involved in the biosynthesis of erythritol from glycerol by Yarrowia lipolytica yeast. In the bioreactor batchcultures, strain A-3 was able to produce from 25.3 g dm−3 to 84.7 g dm−3 of erythritol from 150 g dm−3 of glycerol depending on the initial osmotic pressure. At the osmolality of 4.2 mol kg−3 or higher, a long lag-phase was observed. An enhancement of the production parameters was observed in a culture with the osmotic pressure maintained at an equal level by a step-wise addition of NaCl. The two-hour exposure of strain A-3 cells to 75 g dm−3 of NaCl resulted in decreased activity of glycerol kinase and glycerol-3-phosphate dehydrogenase by about 78 % and 25 %, respectively. The activity of transketolase and erythrose reductase remained unchanged after the salt addition. It was demonstrated that assimilation of glycerol was effective at lower osmotic pressures and that transketolase and erythrose reductase played a significant role in the erythritol formation in Y. lipolytica.