EFFECT OF SALINITY IN THE GROWTH OF THE MARINE YEAST RHODOTORULA-RUBRA

The marine yeast Rhodotorula rubra was studied to determine its respon se to saline stress in batch cultures at different temperatures. An in crease in the salt concentration (4, 8 and 12%) resulted in a decrease in the specific cell growth rate from 0.27 to 0.05 h(-1) at 20 degree s C. At higher temperatures (25 and 30 degrees C), the effect was less noticeable (from 0.32 to 0.14 h(-1)). Intracellular solute concentrat ion (carbohydrates and free amino acid) decreased with increasing sali nity. Therefore, the participation of these two kinds of metabolites i n the osmoregulation of R. rubra was excluded. While the total lipid c ontent of the cells increased with salinity, a close correlation betwe en intracellular glycerol concentration and medium salinity was observ ed, suggesting its participation in osmoregulation. The glycerol pool concentration (157.08, 302.65 and 650.63 mu g/mg dry wt(-1)) may balan ce the osmotic pressure in culture media of 4, 8 and 12% NaCl.