Heterologous β-glucosidase in a fungal cellulase system: Comparison of different methods for development of multienzyme cocktails

• Aspergillus niger β-glucosidase (AnBGL) boosts hydrolytic performance of cellulases.
• Cofermentation of cellulase and AnBGL-expressing Penicillium strains was carried out.
• 113% increase in glucose yield in Avicel hydrolysis was achieved using this approach.
• Cofermentation of two strains of the same fungus is promising.

Three approaches for enrichment of Penicillium verruculosum cellulase multienzyme cocktails with a heterologously expressed Aspergillus niger β-glucosidase (AnBGL) for boosting the hydrolytic performance of cellulases were tested. The best boosting effects (73–113%) on glucose yield in 72-h hydrolysis of milled aspen wood and Avicel provided the enzyme preparation obtained by cofermentation of two P. verruculosum strains, one of which was a basic high-cellulase strain, while the other was capable to produce the heterologously expressed AnBGL (up to 80% of the total protein when used in a separate fermentation). Two other approaches, based on individual fermentations of P. verruculosum strains, carrying the heterologous AnBGL under the control of either a strong cbh1 gene promoter or a weaker hist4 gene promoter, also provided notable boosting effects, although they were less pronounced than in the first mentioned case.

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