Cryopreservation at-80A degrees C of Agaricus blazei on rice grains

Abstract

The preservation of Agaricus blazei is generally done by mycelial subculturing, but this technique may cause genetic degenerations. Despite this, there is not an efficient protocol established to preserve this fungus and cryopreservation could be an alternative. This study aimed to evaluate two freezing protocols for cryopreservation at -80A degrees C of A. blazei strains. Five fungus strains grown on rice grains with husk and were transferred to glycerol (10%) in cryovials. Next, the cryovials were submitted to two freezing temperature protocols: (1) cryopreservation starting at 25A degrees C, then at 8A degrees C for 30 min and kept at -80A degrees C; (2) cryopreservation starting at 25A degrees C, then 8A degrees C for 30 min, -196A degrees C for 15 min and kept at -80A degrees C. After 1 year of cryopreservation, the cryovials were thawed in a water bath at 30A degrees C for 15 min and transferred to malt extract agar medium. It was concluded that the one-year cryopreservation process of A. blazei, grown on rice grains and cryopreserved at -80A degrees C in glycerol 10%, is viable. The slow freezing, from 8 to -80A degrees C, is effective whereas the fast freezing, from 8 to -196A degrees C and then to -80A degrees C, is ineffective. The different genetic characteristics among the strains of this fungus do not interfere in the cryopreservation process.