Abstract:

The ability of cell to modulate the fluidity of plasma membrane was crucial to the survival of microorganism at low temperature. Plasma membrane proteins, fatty acids and carotenoids profiles of Antarctic psychrophilc yeast Rhodotorula sp. NJ298 were investigated at-3 ℃, 0 ℃ and 8 ℃. The results showed that plasma membrane protein content was greater at-3 ℃ than that at 8 ℃, and a unique membrane polypeptide composition with an apparent molecular mass of 94.7 kDa was newly synthesized with SDS-PAGE analysis; GC analysis showed that the main changes of fatty acids were the percentage of unsaturated fatty acids (C_18:1 and C_18:2) and shorter chain saturated fatty acid (C10:0) increased along with the decrease of the culture temperature from 8 ℃ to-3 ℃; HPLC analysis indicated that astaxanthin was the major functional carotenoids of the plasma membrane, percentage of which increased from 54.6±1.5% at 8 ℃ to 81.9±2.1% at-3 ℃. However the fluidity of plasma membrane which was determined by measuring fluorescence anisotropy was similar at-3 ℃, 0 ℃ and 8 ℃. Hence these changes in plasma membrane's characteristics were involved in the cellular cold-adaptation by which NJ298 could maintain normal plasma membrane fluidity at near-freezing temperature.

Key words: psychrophile yeast, plasmamembrane fluidity, fatty acid, protein, carotenoids, cold-adaptation