ISOLATION OF ASTAXANTHIN-OVERPRODUCING MUTANTS OF PHAFFIA-RHODOZYMA

We isolated mutants of Phaffia rhodozyma strain NRRL Y-17269 that over produced astaxanthin when grown on corn-based fuel ethanol stillage (t hin stillage, TS, or fuel ethanol byproducts). Ten mi cultures of muta nt strain JB2 produced 1.54+/-0.21 mu g carotenoid/mg dry weight when grown on 70% thin stillage at pH 5.2, compared with 0.38+/-0.04 mu g/m g produced by the parental strain. Furthermore, JB2 produced similar a staxanthin concentrations when grown in either thin stillage or yeast malt broth. By comparison, previously described astaxanthin overproduc ing strain NRRL Y-17811 yielded 1.08+/-0.07 mu g/mg in yeast malt brot h but only 0.67+/-0.03 mu g/mg in thin stillage. Five liter fermentati on experiments using JB2 grown on 70% thin stillage at pH 5.2 yielded 2.01+/-0.17 mu g/mg astaxanthin. Thus, JB2 is uniquely suited for asta xanthin production from low cost thin stillage.