Expression of a heterologous laccase by Aspergillus niger cultured by solid-state and submerged fermentations

Laccase gene IV from Trametes versicolor was inserted by REMI in Aspergillus niger C28B25. One selected transformant (C28eco3) was subjected to a second round of transformation and a new transformant was isolated (C28eco3–13). Laccase production was compared for these strains in submerged fermentation (SmF) and solid-state fermentation (SSF) using glucose or maltodextrin at different concentrations (10, 50 and 100 g/L). Enzymes yields were higher with glucose as a carbon source. However, repression of laccase was evident for SmF after increasing glucose from 10 to 50 g/L. In contrast, in SSF glucose at 50 g/L allowed the production of the highest laccase activity for strain C28eco3 (362 U/L) and C28eco3–13 (592 U/L). Advantages of SSF as an expression and production system over SmF are also discussed.