Production of Organically Bound Selenium Yeast by Continuous Fermentation

• Published in: Journal of agricultural and food chemistry 1999-06, Vol.47 (6), p.2491-2495
• Main Authors: Demirci, Ali, Pometto, Anthony L
• Format: Article
• Language: English
• Subjects: Arsenicals - metabolism; Biological and medical sciences; biomass; Biotechnology; continuous fermentation; culture media; Fermentation; Food industries; Fundamental and applied biological sciences. Psychology; inorganic salts; ion transport; Methods. Procedures. Technologies; Microbial engineering. Fermentation and microbial culture technology; mineral content; nutrient availability; nutrient content; nutrient sources; organic compounds; organoselenium compounds; Research and development. New food products, dietetic foods and beverages; Saccharomyces cerevisiae; Saccharomyces cerevisiae - metabolism; Selenic Acid; selenium; Selenium Compounds - metabolism; sodium selenate; sodium selenite; Sodium Selenite - metabolism; sodium sulfate; sulfur
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf981198y

This paper describes a protocol for incorporation of sodium selenite or sodium selenate into Saccharomyces cerevisiae biomass by continuous fermentation in a medium with minimal sulfur and methionine concentrations. Selenium incorporation was followed by atomic absorption analysis and methylene blue reduction time (MBRT). Continuous fermentation at 0.2 h-1 dilution rate and sodium selenite addition gradient up to 0.69 g/L of Na2SeO3 yielded 1.89 g/L of biomass with 1904 μg of selenium/g of dry biomass. However, MBRT was 0.1 min, which indicated that the majority of selenium was in the inorganic form. On the other hand, continuous fermentation at 0.2 h-1 dilution rate and sodium selenate gradient up to 0.28 g/L of Na2SeO4 yielded 0.76 g/L of dry biomass with 687 μg of selenium/g of dry biomass, and MBRT was 26 min, which indicated a high concentration of organically bound selenium. Overall, the results indicate a Se/S ratio of 3.9:1 and a dry biomass/Se ratio of 5.5:1 as optimal for continuous production of organically bound selenium. Keywords: Selenium; yeast; Saccharomyces cerevisiae; fermentation