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Astaxanthin is a carotenoid, a strong anti - oxidant , and the destruction of organisms, are widely used in food, pharmaceutical , aquaculture , etc. capable of highly efficient quenching inactivated oxygen , thereby eliminating active oxygen . Phaffia yeast is good bacteria for the production of astaxanthin has a short fermentation period , the characteristics of high - density culture is easy to implement . In this paper, the method of evolutionary engineering Phaffia yeast breeding , screening of high-yielding strains . This subject Phaffia yeast wild-type strain As 2.1557 as the original strain composite of ultraviolet light and nitrosoguanidine mutagenesis method for genetically diverse library of strains in shake flask cultures to different concentrations of β - ionone , diphenylamine of NaCl, TiO 2 , H , 2 O 2 and NaClO as evolutionary pressures , evolutionary engineering culture , transfer time for 48h. The evolutionary engineering study found that these substances can inhibit the growth of Phaffia yeast , resulting in high biomass strains disinhibition ; carotenoid inhibitor of β- ionone and diphenylamine evolutionary pressures , shrimp Green accumulation was not obvious , NaCl , TiO 2 H 2 O 2 and NaClO reactive oxygen product in evolution to stimulate the accumulation of astaxanthin in the process . On the the evolutionary engineering proceeds flora filter breeding high-yield strains of six astaxanthin , a preliminary study of their physiological characteristics . The studies show that the evolutionary strain traits be greatly changed from orange-red liquid culture was color change to pink , and the biomass more than tripled ; plate culture of colonies compared to the wild type , the diameter becomes larger , changes color from yellow-orange to red , different from the wild-type flat , rough , dry colonies , evolutionary strain colony becomes raised , moist thick speculated strains produce capsular . Microscopic observation of the evolution of strains , the evolution of strains of cells smaller and more together form even pseudomycelium . The evolutionary strain astaxanthin production has also been improved which the the highest TiO production of astaxanthin 2 evolution resulting strains can reach 1.223mg / L, and the starting strain of wild-type As 2.1557 0.825mg / L phase ratio, increase of about 48.2% .
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