Characterisation of the glycoside hydrolase domain of a novel bi-functional metagenomic clone for use in the biofuel production industry
Thesis (MSc)--Stellenbosch University, 2017.
ENGLISH ABSTRACT: The current practice of 1st generation biofuel production is marred by several hurdles, namely concerns over food security and the moral dilemma created by using edible feedstocks as a biofuel production source. Second generation biofuel production methods stand to take the forefront and address the world’s need for a renewable liquid fuel source without affecting food security and adding value to the abundant lignocellulosic biomass available worldwide. However, in order to achieve this, 2nd generation biofuel production methods need to become more efficient at liberating fermentable glucose from lignocellulosic biomass. Metagenomic sampling and novel enzyme discovery are the most promising sources of finding new, more efficient enzymes from unculturable microorganisms that can degrade lignocellulosic biomass into fermentable glucose more ably than current enzymes used in industry. Industrial enzymes within the biofuels scope are required to be thermotolerant, pH tolerant, resistant to product inhibition and resistant to denaturation by industrial solvents. A novel, bi-functional, ßglucosidase and ß-galactosidase enzyme, termed Clone 3L, was identified via a metagenomic sampling approach. This study outlines the characterization of clone 3L, including the kinetics of the enzyme and an assessment of the suitability of the enzyme within an industrial, 2nd generation biofuel production pipeline. Clone 3L was found to be a promising candidate for use in 2nd generation biofuel production schemes, with the enzyme exhibiting high activity and affinity for its cellobiose substrate and a high degree of tolerance to various solvents, glucose inhibition and a high activity across a wide pH range.
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