Abstract: In order to screen out a method of extracting pure astaxanthin from Rhodotorula mucilaginosa through optimizing wall breaking method,extraction solvent,saponification method and extraction conditions, Rhodotorula mucilaginosa ZTHY2 was selected as the starting strains for astaxanthin extraction.Initially,dry bacterial cells were processed through acid heat method,freeze thawing ultrasonic cleavage method and dimethyl sulfoxide anhydrous ethanol method.Three saponification methods of astaxanthin crude extract,including methanol A method mixed with KOH,methanol B method mixed with KOH and ethanol mixed method with KOH,were adopted with six developing solvents separately.Subsequently,the free astaxanthin was identified by Thin-layer chromatography implemented by column chromatography with 200-300 mesh silica gel to obtain its purity.Ultimately,astaxanthin pure product was determined by High performance liquid chromatograph (HPLC).Results showed that the best breaking wall method of Rhodotorula mucilaginosa ZTHY2 dry cell is acid heat method,and the extraction solvent is a mixture of ethyl acetate and ethanol (2∶1).Furthermore,the saponification solution is ethanol solution of 20 g/L potassium hydroxide and the saponification conditions is 40 ℃,30 min.The adopted spreading agent and eluent is a mixture of n-hexane and acetone (5∶2).The free astaxanthin ratio determined by HPLC was 35%,and the extraction rate was 96.8%.

Key words: Rhodotorula mucilaginosa, astaxanthin, extraction method, acid thermal process