Construction of a Magnesium-Enriched Yeast Strain and Study on Distribution of Magnesium in the Cells

The fusant strains ZBF-23, ZBF-65, and ZBF-90 with both higher biomass and higher magnesium content in cells were constructed by protoplast fusion. These three fusant strains were used as the source of genome shuffling from which a magnesium-enriched yeast strain F3-3 with better ability to enrich magnesium was obtained. The enriched magnesium of the shuffled strain F3-3 was about 1.83 and 1.57 times of that of the primary strains ZB-29 and ZB-104, respectively. Under optimal fermentation condition, the biomass and magnesium content of cells reached 16.16 g L^?1 and 14.26 mg g^?1. In the total enriched magnesium which was incorporated into the yeast cells, the organic magnesium was about 95.7%, which was mainly in vacuoles and mitochondria. Nucleic acid and protein in the cells also combined 2.59 and 2.91 mg Mg²⁺ g^?1, respectively. The magnesium-enriched yeast strain which possesses higher ability to accumulate and convert inorganic magnesium salts could be used as a magnesium-fortified food supplement.