Applied Biochemistry and Biotechnology, Vol.191, No.2, 772-784, 2020
Recombinant Penicillium oxalicum 16 beta-Glucosidase 1 Displays Comprehensive Inhibitory Resistance to Several Lignocellulose Pretreatment Products, Ethanol, and Salt
beta -Glucosidase (BGL) is a rate-limiting enzyme of lignocellulose hydrolysis for second-generation bioethanol production, but its inhibition by lignocellulose pretreatment products, ethanol, and salt is apparent. Here, the recombinant Penicillium oxalicum 16 BGL 1 (rPO16BGL1) from Pichia pastoris GS115 kept complete activity at 0.2-1.4 mg/mL furan derivatives and phenolic compounds, 50 mg/mL sodium chloride (potassium chloride), or 100 mg/mL ethanol at 40 degrees C. rPO16BGL1 retained above 50% residual activity at 30 mg/mL organic acid sodium, and 60% residual activity at 40 degrees C with 300 mg/mL ethanol. Sodium chloride and potassium chloride had a complicated effect on rPO16BGL1, which resulted in activation or inhibition. The inhibition kinetics of the enzyme reaction demonstrated that organic acids and organic acid sodium were non-competitive inhibitors and that ethanol was a competitive inhibitor at <1.5 mg/mL salicin. Moreover, substrate inhibition of the enzyme was found at >2 mg/mL salicin, and the K-m/K-I and K-m/K-SI average values revealed that the inhibitory strength was ranked as salicin-organic acids>organic acids>salicin-organic acid sodium salt>organic acid sodium salt>salicin>salicin-KCl>salicin-NaCl>salicin-ethanol>ethanol.