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dc.contributor.advisor Ncube, I. Masingi, Nkateko Nhlalala 2022-05-20T10:07:58Z 2022-05-20T10:07:58Z 2020
dc.description Thesis (Ph. D. (Microbiology)) -- University of Limpopo, 2020 en_US
dc.description.abstract The use of lignocellulosic biomass for bioethanol production is largely dependent on cost effective production of cellulase enzymes and most importantly, the availability of cellulases with sufficient β-glucosidase activity for complete hydrolysis of cellulose to glucose. Commercial cellulase preparations are often inefficient in the complete hydrolysis of cellulose to glucose. The addition of β-glucosidases to commercial cellulase preparations may enhance cellulolytic activity in the saccharification of cellulose to fermentable sugars. A β-glucosidase producing thermophilic bacterium, Anoxybacillus sp. KTC2 was isolated from a hot geyser in the Zambezi Valley, Zimbabwe. The bacterium identified through biochemical tests and 16S rDNA sequencing, had an optimal growth temperature and pH of 60˚C and pH 8, respectively. The β-glucosidase enzyme had an optimal temperature of 60˚C and a broad pH range for activity, between 4.5 and 7.5 with an optimum at pH 7. The β-glucosidase enzyme retained almost 100% activity after 24 hours’ incubation at 50˚C. The Anoxybacillus sp. KTC2 β-glucosidase was partially purified and a partial amino acid sequence obtained through MALDI-TOF analysis. The whole genome of Anoxybacillus sp KTC2 β-glucosidase was sequenced and a β-glucosidase gene identified. The deduced amino acid sequence corresponded to the peptide sequences obtained through MALDI-TOF, confirming the presence of the a β glucosidase on the genome of Anoxybacillus sp KTC2. Analysis of the deduced amino acid sequence revealed that the β-glucosidase enzyme belongs to the GH family 1. The β-glucosidase gene was isolated by PCR and successfully cloned into an E. coli expression system. The saccharification efficiency of the β-glucosidase enzyme was evaluated through the creation of enzyme cocktails with the commercial cellulase preparation, CelluclastTM. CelluclastTM with the Anoxybacillus sp KTC2 β-glucosidase were used to hydrolyse pure Avicel cellulose, at 50˚C over a 96 hour reaction time. The Anoxybacillus sp KTC2 β-glucosidase enabled a 25% decrease in the total cellulose loading without a decrease in the amount of glucose released. en_US
dc.description.sponsorship University of Limpopo staff development programme and VLIR en_US
dc.format.extent xii, 99 leaves en_US
dc.language.iso en en_US
dc.relation.requires PDF en_US
dc.subject Bioethanol production en_US
dc.subject Production of β-glucosidase en_US
dc.subject Thermophilic bacterium en_US
dc.subject Anoxybacillus sp. en_US
dc.subject.lcsh Fuel cells en_US
dc.subject.lcsh Lignocellulose -- Biotechnology en_US
dc.subject.lcsh Lignocellulose en_US
dc.subject.lcsh Biomass energy en_US
dc.subject.lcsh Thermophilic bacteria en_US
dc.title Production and characteristics of a b-glucosidase from a thermophilic bacterium and investigation of its potential as part of a cellulase cocktail for conversion of lignocellulosic biomass to fermentable sugars en_US
dc.type Thesis en_US

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