Natural zeolite clinoptilolite increases the concentrations of sphingoid bases in the yeast Yarrowia lipolytica

In the present paper, we studied the effect of natural zeolite clinoptiloli te on sphingolipid metabolism in the yeast Yarrowia lipolytica. We also inv estigated if zeolite addition had any impact on cell shape and size, as wel l as on the pH alterations during the culture growth. High performance liqu id chromatography analysis of sphingoid bases obtained by acid hydrolysis o f complex sphingolipids from Y. lipolytica showed that their concentrations markedly rose upon the zeolite addition. The largest increase among the id entified molecular species of sphingoid bases was seen in C18 phytosphingos ine, whose levels rose 6.2-fold and 22.3-fold after culturing cells for 24 and 36 hours respectively in the presence of finely ground zeolite. pH meas urements of the culture medium showed a similarity between pH profiles of c ontrol and zeolite-supplemented cells, suggesting that ion-exchange capacit y was not probably responsible for the observed change in sphingolipid meta bolism. Scanning electron microscopy revealed that zeolite affected cell si ze and shape. Y. liyolytica cells grown in the absence of zeolite were oval -shaped with an average cell size of 0.7-2.7 mum, whereas when cultured wit h zeolite, they were round-shaped and larger, having an average cell size o f 1.3-2.9 mum.