RICE STRAW HYDROLYSATE AS A PROMISING CULTURE MEDIUM FOR ASTAXANTHIN PRODUCTION BY THE RED YEAST XANTHOPHYLLOMYCES DENDRORHOUS

This research aimed to utilize rice straw as a low-cost substrate for astaxanthin production by Xanthophyllomyces dendrorhous TISTR 5730. Rice straw composed of high content of cellulose (35.92?0.51 %) and hemicellulose (21.13?1.93 %). After enzymatic hydrolysis with commercial cellulase, the rice straw hydrolysate contained the maximum of total reducing sugar content of 89.82?0.39 g/L. X. dendrorhous TISTR 5730 was cultivated on rice straw hydrolysate with 20 g/L of initial total reducing sugar as a culture medium. The maximum cell dry weight (5.47?1.45 g/L) with astaxanthin concentration (2.49?0.04 mg/L) was achieved. The kinetics parameters demonstrate the astaxanthin productivity of 0.50?0.01 mg/L/day with the astaxanthin coefficient of 0.13?0.00 mg/g sugar consumed. X. dendrorhous TISTR 5730 was capable to consume the reducing sugar in rice straw hydrolysate up to 97.08?0.03 %. The absorption spectra, HPLC profile and FTIR spectrum of the produced astaxanthin X. dendrorhous TISTR 5730 were characterized and compared to standard astaxanthin. This research indicated that rice straw hydrolysate could be used as a promising culture medium for astaxanthin production.