Solid-state fermentation of cereal grains and sunflower seed hulls by Grifola gargal and Grifola sordulenta

• Solid-state fermentation formulated substrates by Grifola gargal and Grifola sordulenta is studied.
• Wheat in 1 l bottles and 24 °C are recommended for grain culture.
• Sunflower seed hulls are a good substrate in SSF by both G. gargal and G. sordulenta.
• Supplementation with Cu(II), Zn(II), and Mn(II) salts improves G. gargal and G. sordulenta yields.
• Mushroom induction requires a cold shock and subsequent low temperatures.

Grifola gargal and Grifola sordulenta are edible and medicinal mushrooms from Andino-Patagonian forests. There is a need to find an alternative source for these mushrooms other than gathering them due to increasing pressure on their habitats. Thus, in order to find an appropriate technological pathway to grow these mushrooms, solid-state fermentation (SSF) in different substrates was studied. Mycelia cultivation on grains exhibited the best results when using wheat grains at pH 5.3, 24 °C, in darkness. When using sunflower seed hulls (SSH) the protein content of the growth medium increased significantly after 45 days SSF and a good laccase activity was measured. Further mycelium growth optimization was achieved in the presence of 0.01 N H2SO4, 20 μg/g Mn(II) and 100 μg/g Zn(II) in G. gargal (50% SSH and 30% milled SSH, 15% residual substrate of Pleurotus ostreatus, and 5% wheat bran) and in G. sordulenta (80% SSH, 15% residual substrate of P. ostreatus and 5% wheat bran). Present preliminary studies on basidiome production showed that cultivation conditions should require at least a sterile substrate, 10–12 % inoculation rate, cold shock for primordia induction, and control from air borne contamination.