Zinc- and magnesium-biofortified Pleurotus eryngii mycelial biomass: Bioaccumulation, safety, and functional food potential

Introduction: Inadequate zinc and magnesium intakes affect about 16% and 31% of the world’s population, respectively, and mineral salts used for correction have limited, form-dependent bioavailability. This study evaluated zinc- and magnesium-biofortified Pleurotus eryngii mycelial biomass as a candidate functional food ingredient. Methods: Strain MT-40.32 was pre-cultivated in submerged medium with magnesium and zinc sulfates at a calculated (X1) or double (X2) dose and grown by solid-state fermentation (SSF) on buckwheat hull-wheat bran (70:30) for 21 days. A mycelium-rich fraction of the freeze-dried colonized substrate was analysed for 40 elements by ICP-MS and assessed against TR CU 021/2011 and GOST R 52349-2005. Results: Relative to control biomass, magnesium increased 1.49-fold at X1 and 9.95-fold at X2 (3688 ± 369 µg/g) and zinc 2.39- and 3.80-fold, respectively; a mass balance indicated proportional zinc but disproportionate magnesium transfer. In X2 biomass all regulated toxic elements were below their limits on the dry-weight basis (mercury 36.2 ± 5.4%), whereas mercury exceeded the limit in control and X1 biomass. A 30 g portion of X2 biomass would supply 27.7% of the magnesium and 19.7% of the zinc reference intake. Novelty of the Study: This is the first full report of combined zinc and magnesium biofortification of P. eryngii by SSF on buckwheat hull with 40-element safety screening. Conclusions: In this single-lot study only X2 biomass met both the nutrient-contribution criterion and the regulatory limits. Replicate fermentations, mercury-specific analysis, bioaccessibility testing and clinical validation must precede functional food claims.