Preliminary study on the anti-CO2 stress and growth ability of hypsizygus marmoreus mutant strain HY68

Abstract

Background: A high concentration of CO₂ will stagnate the development of the newly formed primordia of Hypsizygus marmoreus, hinder the development of the mushroom cap, thereby inhibiting the normal differentiation of the fruiting body. Moreover, in the previous experiment, our research group obtained the mutant strain HY68 of H. marmoreus, which can maintain normal fruiting under the condition of high concentration of CO₂. Our study aimed to evaluate the CO₂ tolerance ability of the mutant strain HY68, in comparison with the starting strain HY61 and the control strain HY62. We analyzed the mycelial growth of these strains under various conditions, including different temperatures, pH levels, carbon sources, and nitrogen sources, and measured the activity of the cellulose enzyme. Additionally, we identified and predicted β-glucosidase-related genes in HY68 and analyzed their gene and protein structures.

Results: Our results indicate that HY68 showed superior CO₂ tolerance compared to the other strains tested, with an optimal growth temperature of 25 °C and pH of 7, and maltose and beef paste as the ideal carbon and nitrogen sources, respectively. Enzyme activity assays revealed a positive correlation between β-glucosidase activity and CO₂ tolerance, with Gene14147 identified as the most closely related gene to this activity. Inbred strains of HY68 showed trait segregation for CO₂ tolerance.

Conclusions: Both HY68 and its self-bred offspring could tolerate CO₂ stress. The fruiting period of the strains resistant to CO₂ stress was shorter than that of the strains not tolerant to CO₂ stress. The activity of β-GC and the ability to tolerate CO₂ were more closely related to the growth efficiency of fruiting bodies. This study lays the foundation for understanding how CO₂ regulates the growth of edible fungi, which is conducive to the innovation of edible fungus breeding methods. The application of the new strain HY68 is beneficial to the research of energy-saving production in factory cultivation.

Keywords: Gene expression; Growth rate; Hypsizygus marmoreus; Structure prediction; β-glucosidase.