A step forward in laccase exploitation: Recombinant production and evaluation of techno-economic feasibility of the process

Protein heterologous production offers viable opportunities to tailor laccase properties to specific industrial needs. The high redox potential laccase PDXAlb from Pleurotus ostreatus was chosen as case study of marketable enzyme, due to its desirable properties in terms of activity/stability profile, and already assessed applicability. PDXAlb was heterologously produced in Pichia pastoris by investigating the effect of inducible and constitutive expression systems on both the yield and the cost of its production. System performances were first assessed in shaken-flasks and then scaled-up in bioreactor. The production level obtained in the inducible system is 42 U/mL, while the activity value achieved with the constitutive one is 60 U/mL, the highest obtained in constitutive systems so far. The economic feasibility of recombinant laccase production was simulated, describing the case of an Italian small-medium enterprise. Two scenarios were evaluated: Scenario (I) production based on methanol inducible system; Scenario (II) production based on the constitutive system, fed with glycerol. At all the scales the glycerol-based fermentation is more economic than the methanol-based one. The price forecast for rPDXA1b production is 0.34(sic) k U-1 for glycerol-based process, and is very competitive with the current price of commercial laccase.