Edible Mycelium: A novel biofortification vehicle addressing iron deficiency

Iron deficiency anemia (IDA) is a public health concern. A reduction in the use of animal-based foods, though environmentally friendly, might result in populations consuming plant-based foods, most of which contain poorly bioavailable iron, and thus, inadvertently placing populations at risk of IDA. Edible mycelium is a sustainable production practice, which can be a good source of protein and a suitable vehicle for iron biofortification. The objective of the present study was to evaluate iron bioaccumulation capacity in the mycelium of six common edible fungi species (5 species of wood decay fungi, 1 ectomycorrhizal fungus) grown in iron-rich media.

Grifola frondosa(Polyporales), Flammulina velutipes(Agaricales), Hypsizygus tessulatus(Agaricales), Laccaria ochropurpurea(Agaricales), Morchella angusticeps(Pezizales) and Pleurotus eryngii(Agaricales) were grown in Potato Extract Agar in which Fe concentrations were either 0 ppm (control) or 50 ppm at 24-25°C for 60 days. Mycelial biomass was then removed from the medium surface and washed with 200 mL of ultrapurified water at 90°C. The excess water was removed by centrifugation of 3000 rpm for 15 min at 25°C. Precipitate (mycelium) was dried at 55°C with air circulation until completely dried, and then pulverized. Iron was measured using atomic emission spectroscopy, in which ground mycelium (0.1-0.2 g) was oxidized with acid (nitric acid: hydrochloric acid, 3:1 v/v) under pressure and heated up to 180°C.

All species accumulated more iron than their controls. Iron addition resulted in 5.3-fold increase for Grifola frondose, in 6.1-fold increase for Flammulina velutipes, 13-fold increase for Hypsizygus tessulatus, 119-fold increase for Laccaria ochropurpurea, 8.8-fold increase for Morchella angusticeps and 5.3-fold increase for Pleurotus eryngii.  In conclusion, Ectomycorrhizal fungus, Laccaria ochropurpurea, showed the highest iron bioaccumulation capacity compared to the wood-decay fungi. Despite growing under the same iron-enriched media, all species differentially bio-accumulated iron. Iron-biofortified mycelium can offer an alternative solution to support nutrition in vulnerable populations.