Discovery of potent antioxidant activity astaxanthin and optimization of culture conditions for its biosynthetic bacteria marine red yeast

Abstract

Objective To identify the astaxanthin, a major secondary metabolite produced by Rhodotorula sp, and to optimize the culture conditions for the production of astaxanthin. Methods The marine red yeast preservation strain was subjected to activation culture and fermentation culture. Single factor and response surface test was designed to optimize fermentation conditions. Secondary metabolites of marine red yeast were analyzed by HPLC, and secondary metabolites of marine red yeast were identified by standard samples. The antioxidant activity of marine red yeast astaxanthin was detected in the study. Results A strain of marine red yeast Rhodotorula sp isolated from a polar separation source was found to produce a variety of metabolites, the main metabolite of which was astaxanthin. Single factor experiments showed that the amount of added zinc sulfate was 100.00 mg/L, and the highest yield of astaxanthin was 24.10 mg/ml. The added amount of acetylsalicylic acid was 100.00 mg/L, and the highest yield of astaxanthin was 25.00 mg/ml. When fermentation time lasted for 5 days, the highest yield of astaxanthin was 25.30 mg/mL. The surface response experiments indicated that the fermentation time was 6.64 days, when the added amount of zinc sulfate was 113.50 mg/L, and when the added amount of acetyl chloride was 111.00 mg/L, the astaxanthin output in Rhodotorula sp. fermentation broth was 27.00 mg/ml. The marine red yeast astaxanthin and other antioxidants have significant antioxidant activity. Conclusion Astaxanthin discovered from the polar separation source, the polar marine red yeast, Rhodotorula sp. is a main secondary metabolite. The use of zinc sulfate and acetylsalicylic acid to regulate the biosynthesis of astaxanthin could enrich the production of astaxanthin. The research results might provide an acess for large-scale production of astaxanthin. Key words: Rhodotorula benthica; Secondary metabolite; HPLC; Astaxanthin; Optimization