Improving the expression and secretion of GH48 family cellulases in C. acetobutylicum

Wilding-Steele, Tom (2018) Improving the expression and secretion of GH48 family cellulases in C. acetobutylicum. PhD thesis, University of Nottingham.

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Abstract

Although most energy is currently generated from fossil fuels, their continued use is unsustainable. Biofuels provide an attractive alternative. Unfortunately, such fuels are mainly produced from food crops, causing issues with food security. Lignocellulosic biomass represents the most logical alternative feedstock. However, its recalcitrance means that its use is currently limited by the economic costs involved in its deconstruction. One possible solution would be to undertake consolidated bioprocessing (CBP), a method by which cellulase production, cellulose degradation and fermentation take place in one step. To date, however, no suitable organism(s) have been identified.

Clostridium acetobutylicum is a promising candidate for the generation of a truly CBP organism as it can utilise all sugars present in lignocellulose and it has been used at an industrial scale to produce butanol. It is, however, not cellulolytic. Previous studies have shown that the main barrier to engineering C. acetobutylicum to grow on lignocellulose is the low level of production of cellulases from the GH9 and GH48 families. For this reason, the primary aim of this project was to increase the production of these particular cellulases.

To accomplish the project’s goal, several attempts were made to increase the level of expression of genes encoding GH48 family hydrolases in C. acetobutylicum. These cellulases were shown to be able to bind specifically to N-deacetylated but not acetylated peptidoglycan. C. acetobutylicum’s peptidoglycan was determined to be partially N-deacetylated. Proteins binding to peptidoglycan have been shown to be toxic to cells, which may explain the low level of secretion of GH48 family cellulases by C. acetobutylicum.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Katalin, Kovacs
Minton, Nigel
Subjects: Q Science > QR Microbiology > QR 75 Bacteria. Cyanobacteria
Faculties/Schools: UK Campuses > Faculty of Medicine and Health Sciences > School of Life Sciences
Item ID: 49716
Depositing User: Wilding-Steele, Tom
Date Deposited: 27 Sep 2021 14:20
Last Modified: 27 Sep 2021 14:21
URI: http://eprints.nottingham.ac.uk/id/eprint/49716

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