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Dependence of sphingoid bases concentration on growth phase and addition of zeolite in brewer’ s yeast

Sphinganine, phytosphingosine and ceramide, which are precursors of sphingolipids are involved in membrane signalling, regulation of cell wall biosynthesis, phospholipid biosynthesis and binding of cell surface glycoproteins.In addition, they are proven to play important roles in signal transduction during heat stress response, regulation of calcium homeostasis or components in calcium- mediate signalling pathways and in regulation of the cell cycle. Since little is known about the regulation of de novo synthesis of complex sphingolipids in any organism, an investigation into the regulation of the sphingoid bases’ biosynthesis in yeast may shed some light on this issue. The aim of our research was to investigate the effect of growth phase on the concentration and composition of sphingoid bases from brewer's yeast. The second aspect of our research was to investigate the effect of natural zeolite clinoptilolite on sphingolipid metabolism in brewer's yeast.The yeast cells were cultured in semi-industrial bioreactors in growth medium unhopped worth and in zeolite- supplement growth medium (1% zeolite into basic medium). Total sphingoid bases were extracted according to Riley at al. O-Phthaladehyde derivatives were analysed using reversed-phase high performance liquid chromatography (HPLC). The results point to the following conclusions: brewer's yeast is a good source of sphingolipids and the predominant sphingoid base is phytosphingosine ; the level of total sphingoid bases in brewer’ s yeast changes depending on culture growth phase ; the most obvious effect of the growth phase on the sphingoid base production has been observed in the case of phytosphingosine, the concentration of which is highest in the exponential phase ; natural zeolite clinoptilolite increased the concentration of pytosphingosine which may indicate that zeolite acted at the level of phytosphingosine formation.

sphingolipids ; brewer's yeast ; HPLC ; zeolite

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