Isolation and Identification of Selenium-enriched Yeast from Marine Sources and Optimization of Fermentation Process

Objective: The aim of this study was to isolate and screen yeast with selenium enrichment function from marine samples, and its optimal fermentation conditions to enhance the selenium enrichment of the screened strain was investigated. Methods: A combination of selenium-tolerant and red selenium methods was used to screen the marine source microorganisms with high selenium enrichment capacity from mangroves in East Harbour National Nature Reserve, Hainan Province, and the strains were identified by morphological, physiological, biochemical and molecular biological approaches. The selenium content of the strain was quantified by 3,3'-diaminobenzidine hydrochloride, the optimal fermentation process to enhance the selenium enrichment of the screened strain was conducted by single-factor tests. Results: A safe strain of Lachancea fermentati HN-10 with selenium enrichment function was obtained from the marine source samples and its optimal fermentation process of 5% inoculum, initial pH6, fermentation temperature 22 ℃, fermentation speed 180 r/min, fermentation time 48 h and selenium addition 20 μg/mL was achieved. Under the optimal fermentation process, 4.52 g/L biomass density, a 1.57 mg/g selenium enrichment, and 35.43% selenium conversion was obtained. Conclusion: The L. fermentati HN-10 from marine source has potential application for the development of selenium-enriched food.