Cell growth and Trametes versicolor laccase production in transformed Pichia pastoris cultured by solid-state or submerged fermentations

摘要

BACKGROUND: Growth kinetics of Pichia pastoris and heterologous expression of Trametes versicolor laccase were compared. This is the first study of its kind between solid-state yeast cultures done on polyurethane foam (PUF) and submerged liquid fermentations (SmF). RESULTS: Themaximum values of biomass were similar for SSF (solid-state fermentation) and SmF experiments when the BOD (biochemical oxygen demand) was lower than 100 g L1. For higher BOD levels, themaximum values of biomass were 55 g L1 (SSF) and 35 g L1 (SmF). Micrographs of PUF preparations showed yeast growing within liquid lamellae, thinner than 100 μm, forming large horizontal aggregates. Yeast aggregates were much smaller in SmF than in SSF experiments; however, laccase expression was lower in PUF than in SmF, unless the methanol concentration was increased to 63 g L1, which was inhibitory only to the SmF system. CONCLUSION:Theresults showthatoxygenmass transfer ismoreefficient inSSF,whichis related tothehigher area/volumeratio compared with SmF. Induction differences may also be due to hindered diffusion ofmethanol within large yeast aggregates.