Screening Identification And Fermentation Optimization Of High Squalene Production Yeast Pseudozyma Sp.SD 301

Squalene is a significant precursor of thousands of bioactive triterpenoids and has enormous industrial value as a protective agent, functional food additives, cosmetics and vaccine adjuvant. However, continous supply and future availability of squalene are uncertain because of concerns over preservation of marine wildlife as well as the complexity and instability of chemosynthesis. Plant sources would be desirable without considering low squalene contents and crop production. Therefore, microbe have been explored as an excellent alternative source of squalene. Which have great advantage in so many aspects. This study aims to obtain a high squalene production strain.which has potential in industrial fermentation.Most importantly the fermentation optimization of this study greatly promotes the commercialization of squalene.The detailed results of this study are summarized as follows:1.Screening microbial containing high level of squalene from samples which were collected from typical biotic environment of Yunnan.Guangdong, Zhejiang and Hainan province and strains library of squalene were constructed.2.The marine yeast was identified to be Pseudozyma by 18S rDNA,5.8S rDNA, ITS gene sequences analysis and routine yeast identification methods, as well as the basic physiological, biochemical properties and cellular morphology of the strain.Isolation and identification of squalene producing yeast named Pseudozyma sp.SD301.3.Single factor experiment,Plackett-Burman and Response Surface Methodology (RSM) were applied in fermentation optimization of squalene.The theoretical optimal Culture Conditions are as follows:concentration of glucose was 67.2 g L-1, inoculation quantity was 1.5%(v/v), culture temperature was 26 ℃, loading quantity was 41 mL in a 250mL flask. Under these conditions, the yield of squalene reached 1.152g L-1, which is consistent with the predicted value of 1.1508g L-1, representing a 3.62-fold increase compared to the original conditions.And the yield of squalene was 0.7899g L-1 in 5L bioreactor.