Economizing the lignocellulosic hydrolysis process using heterologously expressed auxiliary enzymes feruloyl esterase D (CE1) and β-xylosidase (GH43) derived from thermophilic fungi Scytalidium thermophilum

Two lignocellulolytic accessory enzymes, feruloyl esterase D (FAED_SCYTH) and beta-xylosidase (XYL43B_SCYTH) were cloned and produced in the Pichia pastoris X33 as host. The molecular weight of recombinant enzymes FAED_SCYTH and XYL43B_SCYTH were similar to 31 and 40 kDa, respectively. FAED_SCYTH showed optimal activity at pH 6.0, 60 degrees C; and XYL43B_SCYTH at pH 7.0, 50 degrees C. FAED_SCYTH and XYL43B_SCYTH exhibited t(1/2): 4 and 0.5 h, respectively (50 degrees C, pH 5.0). The beta-xylosidase was bi-functional with pronounced activity against pNP alpha-arabinofuranoside besides being highly xylose tolerant (retaining similar to 97% activity in the presence of 700 mM xylose). Cocktails prepared using these enzymes along with AA9 protein (PMO9D_SCYTH) and commercial cellulase CellicCTec2, showed improved hydrolysis of the pre-treated lignocellulosic biomass. Priming of pretreated lignocellulosic biomass with these accessory enzymes was found to further enhance the hydrolytic potential of CellicCTec2 promising to reduce the enzyme load and cost required for obtaining sugars from biorefinery relevant pre-treated substrates.

Automated summary

Two lignocellulolytic accessory enzymes were cloned and produced successfully in this study. They showed optimal activity under specific conditions and played important roles in the hydrolysis of pre-treated lignocellulosic biomass.