Abstract: To determine the optimal preservation period for maintaining strain viability, the effects of preservation at 4 ℃ on the extracellular enzyme activities of Morchella esculenta mycelia were investigated, thereby providing a theoretical basis for the preservation of M. esculenta strains. The cultivar ‘Liumei' was stored at 4 ℃ and 20 ℃ for 30, 60, 90, and 120 days, respectively. After each period, the mycelia were recovered at 20 ℃ for 48 h, and the activities of catalase(CAT), carboxymethyl cellulase(CMCase), laccase(Lac), and protease(Pro) were measured. Results indicated that,after 30 d of preservation at 4 ℃, CAT activity significantly increased by 43.35% compared to the initial level, followed by a gradual decline. In contrast, the activities of CMCase, Lac, and Pro exhibited a continuous downward trend as preservation time extended. Compared with the 20 ℃ control, preservation at 4 ℃ significantly delayed the reduction in CMCase activity(P<0.05), although it provided limited protective effects for Lac and Pro activities. Mycelia preserved at 4 ℃ for up to 90 d successfully restored all four enzyme activities to or above initial levels following the 48 h recovery. However, preservation for 120 d led to a significant and irreversible decline in enzyme activities (P<0.05). Storing M. esculenta strains at 4 ℃ could effectively maintain viability for up to 90 d; beyond this threshold, irreversible physiological deterioration occurred. The rebound of laccase activity during the recovery phase might serve as a potential physiological indicator for evaluating strain vitality. This study investigated the changes and recovery of mycelial enzyme activities of M. esculenta under low-temperature stress, which provided a theoretical basis for the preservation of M. esculenta strains.

Key words: Morchella esculenta, low-temperature preservation, extracellular enzyme