Evaluation of the viability of Pleurotus spp. strains after liquid nitrogen cryopreservation

Viability of 6 mushroom strains of the Pleurotus genus (2 from P. djamor va r. djamor, 1 from P. ostreatus var. ostreatus, 2 from P. ostreatus var. col umbinus and 1 from P. pulmonarius after liquid nitrogen cryopreservation (- 196 degrees) was evaluated. The contact time for the mycelia of these strai ns with the cryoprotectant (glycerol) was studied 1, 2 and 3 hours before f reezing. We also tested the effect of different times (5, 10 and 15 minutes ) and temperatures (30, 45 and 60 degrees C) of the thawing system for myce lial recovery. The results showed a marked tendency toward faster mycelial recovery when samples were thawed at 30 degrees C, while at 60 degrees C no recovery was observed. A change in thawing and contact times with the cryo protectant did not affect the results significantly, as the thawing tempera ture and strain employed affected.