Improvement of cellulase and xylanase production in Penicillium oxalicum under solid-state fermentation by flippase recombination enzyme/ recognition target-mediated genetic engineering of transcription repressors.

ABSTRACT

Penicillium oxalicum has received increasing attention as a potential cellulase-producer. In this study, a copper-controlled flippase recombination enzyme/recognition target (FLP/FRT)-mediated recombination system was constructed in P. oxalicum, to overcome limited availability of antibiotic resistance markers. Using this system, two crucial transcription repressor genes atf1 and cxrC for the production of cellulase and xylanase under solid-state fermentation (SSF) were simultaneously deleted, thereby leading to 2.4- to 29.1-fold higher cellulase and 78.9% to 130.8% higher xylanase production than the parental strain under SSF, respectively. Glucose and xylose released from hydrolysis of pretreated sugarcane bagasse achieved 10.6%-13.5% improvement by using the crude enzymes from the engineered strain Δatf1ΔcxrCflp under SSF in comparison with that of the parental strain. Consequently, these results provide a feasible strategy for improved cellulase and xylanase production by filamentous fungi.