Stabilization of astaxanthin by a novel biosurfactant produced by Rhodotorula mucilaginosa KUGPP-1

We found that a novel biosurfactant from the cultured broth of red yeast, Rhodotorula mucilaginosa KUGPP-1, originating in the Antarctic, has dispersive power against astaxanthin. The novel biosurfactant was purified from extracts to the ultrafiltration state by acetone precipitation and chromatography on a DEAE-Toyopearl 650 M, and gel filtration on a Sephacryl S-400 HR. The molecular mass of the novel biosurfactant was estimated to be about 730,000 by gel filtration chromatography. The novel biosurfactant was comprised of sugar and protein in an approximate molar ratio of 9 : 1. The sugars were comprised of mannose, galactose and glucose. The particle size of the astaxanthin (0.13 µ g/ml) micelle was about 410 nm. Astaxanthin was stable to oxidation in the novel biosurfactant micelles. To our knowledge, this is the first report on a glycoprotein type of biosurfactant with astaxanthin-stabilizing ability.