BATCH CULTIVATION AND ASTAXANTHIN PRODUCTION BY A MUTANT OF THE RED YEAST, PHAFFIA-RHODOZYMA NCHU-FS501

Phaffia rhodozyma cells were treated with the mutagenic agent NTG seve ral times and plated on yeast-malt agar containing beta-ionone as a se lective medium, This mutagenesis of the yeast yielded a mutant (NCHU-F S501) with a total carotenoid content of 1454 mu g g(-1) dry biomass, Temperature and pH had only a slight effect on the volumetric pigment production by the red yeast, however astaxanthin yield and specific gr owth rate were influenced more significantly by temperature and pH, Th e optimum inoculum size, temperature and air flow rate for astaxanthin formation by the mutant in a bench-top fermenter were 7.5% (v/v), 22. 5 degrees C and 3.6 vvm, respectively. Glucose (1%, w/v) as carbon sou rce yielded the highest volumetric astaxanthin production (6.72 mu g m l(-1)), Peptone (15.8% total nitrogen) was the best nitrogen source fo r astaxanthin production (6.72 mu g ml(-1)). Pigment formation by the mutant was further improved by increasing the glucose concentration to 3.5%, where the astaxanthin concentration was 16.33 mu g ml(-1). At 4 .5% glucose or above astaxanthin formation was inhibited, Control of t he pH of the fermentation broth did not improve pigment production.