Optimization of Cellulase Production by a Novel Endophytic Fungus Penicillium oxalicum R4 Isolated from Taxus cuspidata

Endophytic fungi inside a plant can degrade a portion of plant lignin and cellulose. Endophytic Penicillium is one of the industrial microorganisms with the advantage of producing enzymes with a complete enzyme system that can be secreted into the extracellular space. The natural evolution of ancient tree species from special natural geographic environments to screen out cellulase-producing strains with excellent characteristics provides a promising direction for future industrial enzymes. The present study successfully isolated and screened a novel fungal endophyte, Penicillium oxalicum R4, with higher cellulase activity from Taxus cuspidata. Under the optimized culture conditions obtained by a Box-Behnken design (BBD) and an artificial neural network-genetic algorithm (ANN-GA), yields of Filter Paperase (FPase), Carboxymethyl Cellulase (CMCase) and beta-glucosidase (beta GLase) produced by P. oxalicum R4 were 1.45, 5.27 and 6.35 U/mL, which were approximately 1.60-fold, 1.59-fold and 2.16-fold higher than those of the non-optimized culture, respectively. The discovery of cellulase-producing strains of endophytic fungi located in special natural geographic environments, such as Taxus cuspidata, which is known as a living plant fossil, provides new research directions for future industrial enzymes.

Automated summary

Endophytic fungi can degrade plant cellulose, and endophytic Penicillium has high cellulase activity. Endophytic fungi in special natural environments offer new directions for future industrial enzyme research.