No abstract

Alternative substrates for cryopreservation at -20°C have been little explored for basidiomycetes and could bring new possibilities of lower cost cryopreservation. Nevertheless, freezing temperatures between -15 and -60°C are very challenging because they frequently result in cryoinjuries. The objective of this study was to evaluate substrates associated to cryoprotective agents for Pleurotus ostreatus cryopreservation at -20 or -70°C in order to develop alternative techniques for basidiomycete cryopreservation. P. ostreatus was grown on potato dextrose agar or whole grains of oat, wheat, rice or millet and transferred to cryovials with cryoprotective solution with 1 % dimethyl sulfoxide, 5 % glycerol, 10 % saccharose, 4 % glucose, 6 % polyethylene glycol-6000 or 5 % malt extract. The mycelium in the cryovials were cryopreserved at -20 or -70°C and recovered for evaluation of the mycelial growth viability after 1 and 3 years. Both substrates and cryoprotectants affect the viability of the mycelial growth cryopreserved at -20 or -70°C; wheat grains combined with cryoprotectants such as saccharose or glucose are effective for keeping mycelium viable after cryopreservation at -20°C for 1 or 3 years; for cryopreservation at -70°C after 1 or 3 years, any substrate combined with any cryoprotectant is effective for preserving the mycelium viable, except for millet grains with polyethylene glycol after 3 years; semi-permeable cryoprotective agents such as saccharose and glucose are the most effective for cryopreservation at -20 or -70°C for at least 3 years.

Many alternative compounds have been tested to improve poultry performance but few of them have previously used mycelial-colonized substrate to partially replace standard diet in broiler chickens. The objective of this study was to evaluate broiler chicken production, health, and meat sensory characteristics, with partial replacement of the standard diet by Pleurotus ostreatus-colonized substrate. One hundred fifty 1-day-old male Cobb chicks were given standard diet partially replaced by 0, 5, 10, 100, or 200 g·kg⁻¹ of P. ostreatus-colonized substrate and randomly distributed into five treatments. Each treatment had three replicates, with 10 birds per replicate, totaling 30 birds. The replacement of the standard diet by 10 g·kg⁻¹ of colonized substrate increased (P≤0.05) chicken body mass up to 57% at 21 days, and up to 28% at 42 days. In general, partial replacement of standard diet by colonized substrate increased hematocrits and typical lymphocytes, and reduced low density lipoproteins. Also, it reduced chicken production period up to 21% and there is no meat taste alteration. The use of P. ostreatus-colonized substrate in chicken feeding is an alternative method to improve broiler chicken production.

This study aimed to evaluate the effects of the solid and semisolid culture medium on the mycelial viability of A. subrufescens after 5-year cryopreservation at − 70°C. Mycelia were grown in three types of whole or ground grains, with or without 5% glycerol addition in the substrate and/or in a cryotube. After 5 years of cryopreservation at − 70°C, every treatment was thawed and recovered in malt extract culture medium with 15 (solid culture medium) or 5 g L −1 (semisolid culture medium) of agar. The semisolid recovery culture medium increased the mycelial viability recovery capacity of A. subrufescens cryopreserved for 5 years in grains with glycerol only in the cryotube, and specifically with medium-hard wheat grain without glycerol addition at all. Agar-based substrates such as malt extract agar, agar-ground grain, or the one with glycerol addition to the substrate were not effective to keep the mycelial viability, regardless of the recovery culture medium consistency. Hard and medium-hard endosperm wheat grains or hard endosperm rye grains with addition of glycerol as cryoprotectant only to the cryotube were effective to cryopreserve the fungus for 5 years without cryoprotectant addition in the substrate.