The study aimed at determining which part of magnesium bound with feed’s yeast C. utilis ATCC 9950 during batch culture in control (YPD) and experimental medium (YPD with the addition of magnesium) remains in the cell wall and which undergoes intracellular bioaccumulation. The experimental mediums were supplemented with the amount of MgCl₂×6H₂O providing 1.25 g/dm³ or 2.0 g/dm³ content of Mg²⁺ ions. Moreover determinated addition of magnesium ions into experimental mediums on the total protein contents in the yeast biomass. The cultures were run for 48 hours at 28˚C in a reciprocating shaker which provided aerobic conditions of the process. The application of mechanical disintegration of the yeast cells (at a temperature of liquid nitrogen) enabled determination of the contents of magnesium and total protein in both cell walls and protoplasts. The yeast biomass from YPD medium (enriched with magnesium) contained about tree times more magnesium then from control medium. Average 80% magnesium was localised in the cell walls, but only 20% in protoplasts. After 48-hour cultivation average 60% magnesium ions were in the cell walls and 40% in the yeast protoplasts. The addition of Mg²⁺ ions to the experimental media evoked a significant (evan 20%) increase in the total protein content in the yeast biomass compared to the control medium culture.

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