Effect of polar and non-polar carotenoids on Xanthophylomyces dendrorhous membranes by EPR.

The red yeast Xanthophyllomyces dendrorhous is one of the microbiological production systems for natural carotenoids. High-performance liquid chromatography (HPLC) and electron paramagnetic resonance spectroscopy (EPR) experiments were performed on X. dendrorhous membranes in order to study the effect of incorporation rates of different type of carotenoids. In the case of fluid-phase membranes, it was found that polar carotenoids, such as astaxanthin and cis-astaxanthin, increased the EPR order parameter and decreased the motional freedom and phase-transition temperature. In contrast the non-polar carotenoids beta-cryptoxanthin and beta-carotene decreased the EPR order parameter and increased motional freedom and phase-transition temperature. A noteworthy coherence was observed between the polarities of the strains and the phase-transition temperatures.