Cellulolytic enzymes production guided by morphology engineering

Abstract

Endoglucanase and xylanase are critical enzymes for liquefaction and enzyme hydrolysis of high solids lignocellulosic biomass to facilitate its transport and production of desired derived products. Here is reported how combinations of different spore concentrations and pH influence microbial morphology, and how this may be used to direct expression and secretion of enzymes by Aspergillus niger. While xylanase production is not affected by A. niger morphology changes, endoglucanase production is enhanced under conditions of lower stress and by morphology that results in pellets. β-glucosidase production is enhanced under dispersed morphology, which results in up to fourfold increase of this enzyme production under the tested experimental conditions. A morphologic scale (Y) is proposed based on a form factor that considers the size and frequency of each morphology class, and that points to conditions that result in high selectivity for either endoglucanase or β-glucosidase production. An equation proposed to relate enzyme activity to morphology provides a useful tool for tuning enzyme production of A. niger, where morphology is a first indication of relative enzyme activities in a fermentation broth.

Keywords: (hemi) Cellulases; Aspergillus niger; Enzymes; Filamentous fungi; Morphology engineering.