Dependence of the sphingoid bases concentration on growth phase and temperature in the yeast Yarrowia lipolytica

The aim of this research was to investigate the effect of growth phase and temperature on the concentrations of the individual molecular species of sphingoid bases obtained by acid hydrolysis of total sphingolipids from the yeast Yarrowia lipolytica. Our results showed C IS phytosphingosine to be the major long-chain base in Y. lipolytica regardless of growth phase or temperature. We also found Y. lipolytica to contain sphingosine, the predominant mammalian long-chain base that is uncommon for yeast sphingolipids. Among the identified long-chain bases, only C18 phytosphingosine appeared to be influenced by culture conditions. Its concentration was largest in the exponential phase and decreased 2.9-fold when cells entered the stationary phase of growth at 28 degreesC. Following a temperature shift from 28 to 39 degreesC, there was a 2.1-fold decrease in the phytosphingosine concentration, but it rose 1.7-fold after the heat-stressed cells had been returned to 28 degreesC and subjected to prolonged growth. These results might point to the possible involvement of phytosphingosine in the cell growth regulation and in the adaptation of Y lipolytica cells to stressful culture conditions.