The Effects of Different Temperatures on the Mycelial Growth Dynamics and Enzyme Activity of 16 Poria Cocos Strains

To investigate the effects of different temperatures on the mycelial growth dynamics and changes in enzyme activity of various Poria cocos strains, and to screen for strains suitable for cultivation at higher temperatures. Sixteen P. cocos strains collected from Yunnan, Hubei, Anhui, and other regions were used as study subjects. Test tube culture media were prepared using pine sawdust as the main ingredient, supplemented with rice husks and wheat flour. Three constant-temperature gradients were established at 25, 30, and 35℃. Measurements of mycelial growth characteristics and extracellular enzyme activity were conducted for each strain across the three temperature gradients, and a comprehensive evaluation was performed using correlation analysis combined with the membership function method. The results showed that the hyphal growth rates of P. cocos strains cultured at 25℃ ranged from 0.89 to 1.60 cm/d, with Wild P. cocos and P. cocos 5.78 (Wuhan) significantly higher than other strains. At 30℃, hyphal growth rates ranged from 1.45 to 1.77 cm/d, with Wild P. cocos exhibiting the fastest growth. while at 35℃, the hyphal growth rate ranged from 1.11 to 1.66 cm/d, with Yunnan 2 being the fastest; Guangdong P. cocos exhibited the highest polyphenol oxidase activity under both 25℃ and 35℃ cultivation conditions, at 130.36 U/g and 132.24 U/g, respectively; The Anhui 1 strain exhibited a manganese peroxidase activity as high as 430.97 nmol/(min·g) when cultured at 25℃, significantly higher than that of all other strains under different treatments; the highest laccase activity was observed in P. cocos FL21 at 25℃, at 121.89 U/g; Yunnan 1, Yunnan 3, Wanyou No. 1, P. cocos 5.78 Anqing, Guizhou 1, Qipo P. cocos, and P. cocos FL21 showed increasing cellulase activity with rising temperature. There were no significant differences in hemicellulase activity among the strains at different temperatures, with the highest activity observed in Guizhou 1 at 35℃, at 139.71 nmol/(min·g). Overall, the cellulase, hemicellulase, and polyphenol oxidase activities of the 16 P. cocos strains were higher at 30℃ or 35℃ than at 25℃. 30℃ is the most suitable temperature for in vitro cultivation of P. cocos, with Yunnan 2 and P. cocos FL21 demonstrating superior performance among the strains.