Sustainable Cultivation of Ascomycete Fungi on Wheat Bran for Hydrolytic Enzyme Production

Abstract

To increase its product sustainability portfolio the detergent and personal care industry seeks bio-based alternatives to chemical performance additives in their products. Currently, enzymatic systems for these applications are mainly obtained from genetically modified organisms (GMO). However, these GMO products cannot be included in eco-certified household care formulations. Hence, this study evaluates alternative non-GMO enzymes systems that could be sustainable performance additives. Seven strain variants of Ceratocystis paradoxa and one strain of Aspergillus niger van Tieghem were cultivated in different liquid media with 3 % glucose (0.3 L cultivation volume, 120 rpm, 28 °C, pH 5.5, 336 hours). Specifically, the enzymatic activities were assessed initially qualitatively via 24 chromogenically labeled sugar polymer-substrates targeting various cellulolytic and hemicellulolytic activities. Quantitative assessment via spectrophotometric based on the same set of chromogenic substrates, was limited to cellulose, xylan, mannan, starch, galactan, rhamnogalacturonan and casein substrates. Using these assays, the C. paradoxa strains showed dominant cellulase, xylanase, amylase and galactanase activities, while the A. niger strain showed amylase and protease activities among other minor hydrolytic enzyme activities. To evaluate the efficiency of the respective hydrolase enzyme systems were concentrated and applied in the hydrolysis of wheat bran. Wheat bran a cereal milling by-product, which is available at low cost in high quantities, provides an ecologically and economically relevant carbon source for fungal cultivation. Hence, the ability of the new enzyme systems to liberate fermentable sugars was identified as a measure of efficiency. The best performing enzyme systems were identified in terms of total sugar released.

Keywords

• biomass hydrolysate
• biorefinery
• bioremediation
• cleaning agents
• enzymatic hydrolysis
• fungal strains
• laundry detergents
• wheat bran hydrolysis