Recombinant Production, Fed-batch Fermentation and Characterization of a New Ferulic Acid Esterase from Aspergillus terreus

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http://urn.fi/URN:NBN:fi:hulib-201703131445
Title: Recombinant Production, Fed-batch Fermentation and Characterization of a New Ferulic Acid Esterase from Aspergillus terreus
Author: Koskela, Salla
Contributor: University of Helsinki, Faculty of Agriculture and Forestry, Department of Food and Environmental Sciences
Publisher: Helsingfors universitet
Date: 2016
Language: eng
URI: http://urn.fi/URN:NBN:fi:hulib-201703131445
http://hdl.handle.net/10138/178526
Thesis level: master's thesis
Discipline: Bioteknik (EYT)
Biotechnology (EYT)
Biotekniikka (EYT)
Abstract: Fungal ferulic acid esterases (FAEs) are important accessory enzymes that participate in degradation of plant cell wall hemicellulose in grasses, including cereals and many energy crops. They could be used to convert agricultural wastes into a variety of value-added products such as biofuel, feed and paper. In non-aqueous media, they have been shown to act as catalysts for enantioselective reactions. Putative faes are widespread in genomes of plant pathogenic and saprotrophic fungi. However, only few FAEs have been characterized in detail. Additionally, despite of their diverse biotechnological potential, fungal FAEs have not been produced recombinantly on a bioreactor scale, which is a necessary step for their commercial applications. The aim of the present study was recombinant production on a bioreactor scale and biochemical characterization of a putative FAE from Aspergillus terreus. The enzyme demonstrated a broad substrate profile and an excellent storage stability. Its catalytic activity was highest against methyl 3,4-dimethoxycinnamate, but the enzyme was also active against methyl ferulate. It preferred methoxy groups to hydroxyl groups on the substrate’s phenyl ring, while shortening of the aliphatic side chain diminished the activity. The enzyme was observed to be fully stable at 37 °C for 1 h, and it demonstrated thermal activation at the same temperature. At 45 ˚C, it retained 75 % of its initial activity for 1 h. McIlvaine’s buffer was observed to increase the activity by 85 % compared to the standardly used MOPS buffer. The results of this study have contributed to the biochemical knowledge of fungal FAEs and elucidated their substrate preferences.
Subject: Aspergillus
fermentation
ferulic acid esterase
lignocellulose
plant biomass degradation


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