The activity and molecular characterization of a serine proteinase in Pleurotus eryngii during high carbon dioxide and low oxygen storage

• The Spr activity during postharvest storage was investigated in P. eryngii.
• The full-length PeSpr1 cDNA and DNA sequences were cloned in P. eryngii.
• Spr was proposed to play an important role in senescence of P. eryngii.

Pleurotus eryngii has recently become a major cultivated mushroom because of its good taste, flavor, and nutritional factors. The high activity of serine proteinase (Spr) was one of the key factors causing deterioration of mushroom fruit bodies. To investigate the activity and molecular mechanisms of Spr during storage in P. eryngii, the mushrooms were stored under high carbon dioxide and low oxygen treatment (2% O2 + 30% CO2), which was proved to significantly prolong mushroom shelf life. Transmission electron microscopy observation indicated that 2% O2 + 30% CO2 could inhibit the abnormalities of cells compared to ambient air. The activity of Spr in 2% O2 + 30% CO2-treated mushrooms was notably lower than that of control. cDNA and DNA encoding PeSpr1 were amplified and sequenced, which were shown to be homologous to that of other basidiomycota fungal serine proteinases. The spatio-temporal expression of PeSpr1 in the ambient air and 2% O2 + 30% CO2 storages was correlated with Spr activity. These results suggest that PeSpr1 plays an important role in postharvest P. eryngii, and the research on activity and molecular characterization of Spr might propose an available target for prolonging the shelf life of postharvest P. eryngii mushrooms.