Directed Evolution of Saccharomyces cerevisiae for Increased Selenium Accumulation

Area of Science:

• Biotechnology
• Microbiology
• Nutritional Science

Background:

• Selenium-enriched yeast (selenium yeast) is a key supplement in agriculture and human nutrition.
• Current production methods for selenium yeast require optimization for efficiency.
• Identifying yeast strains with superior selenium accumulation is crucial for improving production.

Purpose of the Study:

• To develop and validate a method for selecting yeast strains with enhanced selenium accumulation capabilities.
• To correlate yeast selenite resistance with selenium accumulation under various conditions.
• To identify non-transgenic yeast strains suitable for food and nutritional supplements.

Main Methods:

• Assayed selenite resistance in four diverse Saccharomyces cerevisiae strains under varying carbon, nitrogen, and phosphate conditions.
• Correlated selenite resistance with selenium accumulation in a commercial selenium-growth medium.
• Utilized glycerol- and selenite-containing media for selection of high-accumulation isolates.

Main Results:

• Identified six yeast isolates with enhanced selenite resistance using glycerol- and selenite-containing media.
• One isolate demonstrated a 10-fold increase in selenium accumulation (0.13 to 1.4 mg Se g⁻¹ yeast) compared to its parent strain.
• The selection method successfully identified non-transgenic yeast with high selenium accumulation.

Conclusions:

• Glycerol- and selenium-containing medium effectively selects for yeast strains with enhanced selenium accumulation.
• The developed method improves cost-efficiency in selenium yeast production.
• The selected yeast strains are suitable for human food and nutrient supplements due to the non-transgenic selection process.