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Rhizopus oryzae for fumaric acid production : continuous feed strategies to manipulate the metabolism
Thesis(PhD (Chemical Engineering)) --University of Pretoria, 2022.
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University of Pretoria
2022
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| _version_ | 1867613578045947904 |
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| access_status_str | Open Access |
| author2 | Nicol, Willie |
| author_browse | Nicol, Willie |
| author_facet | Nicol, Willie |
| collection | Thesis |
| dc_rights_str_mv | © 2022 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Thesis(PhD (Chemical Engineering)) --University of Pretoria, 2022. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/88528 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:38:22.209Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2022 |
| publishDateRange | 2022 |
| publishDateSort | 2022 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/88528 Rhizopus oryzae for fumaric acid production : continuous feed strategies to manipulate the metabolism Nicol, Willie u14010357@tuks.co.za Brink, Hendrik Gideon Swart, Reuben Marc UCTD Fumaric acid Lignocellulosic hydrolysate Bioprocessing Fermentation Rhizopus oryzae Engineering, built environment and information technology theses SDG-07 Engineering, built environment and information technology theses SDG-09 Engineering, built environment and information technology theses SDG-12 Engineering, built environment and information technology theses SDG-13 Thesis(PhD (Chemical Engineering)) --University of Pretoria, 2022. The four-carbon dicarboxylic acid, fumaric acid, of the tricarboxylic acid cycle remains a promising bio-based platform chemical. To date the most promising organism for pro- ducing fumaric acid is Rhizopus oryzae (ATCC 20344) that naturally excretes fumaric acid under nitrogen limited conditions. In order to investigate the fumaric acid produc- tion with R. oryzae, a novel immobilised biomass reactor was developed. Fumaric acid excretion in R. oryzae is always associated with the co-excretion of ethanol, an unwanted metabolic product from the fermentation. The cause of ethanol production was suspected to be a result of R. oryzae being a Crabtree-positive organism. For Crabtree-positive or- ganisms like Saccharomyces cerevisiae, ethanol overflow is negated by controlling the glucose input to the fermentation. The same strategy was employed for R. oryzae during a continuous production fermentation. It was shown that ethanol could be eliminated entirely during fumaric acid production, achieving a yield of 0.802 g g−1 fumaric acid on glucose [1]. The medium pH was identified as a key parameter affecting fumaric acid excretion. It was found that the selectivity for fumaric acid production increased at high glucose consumption rates for a pH of 4, different from the trend for pH 5 and 6, achieving a yield of 0.93 g g−1 [2]. This yield is higher than previously reported in the literature. The use of lignocellulosic hydrolysate, predominantly comprised of glucose and xylose, for the production of fumaric acid would greatly improve the industrial viability of the process. A synthetic lignocellulosic hydrolysate (glucose-xylose mixture) was used in batch and continuous fermentations to investigate the feasibility of this substrate. The batch fermentation of the synthetic hydrolysate at the optimal conditions (urea feed rate 0.625 mg L−1 h−1 and pH 4) produced a fumaric acid yield of 0.439 g g−1. A spe- cific substrate feed rate (0.164 g L−1 h−1) which negated ethanol production and selected for fumaric acid was determined. Using this feed rate in a continuous fermentation a fumaric acid yield of 0.735 g g−1 was achieved; a 67.4 % improvement [3]. Metabolic analysis helped to identify a continuous synthetic lignocellulosic hydrolysate feed rate that selected for fumaric acid production, while achieving co-fermentation of glucose and xylose, avoiding the undesirable carbon catabolite repression. Because this work demonstrates the viability of fumaric acid production from lignocellu- losic hydrolysate, the process developments discovered will pave the way for an industri- ally viable process. National Research Foundation, grant number MND200609529524. mi2026 Chemical Engineering PhD(Chemical Engineering) Unrestricted SDG-07: Affordable and clean energy SDG-09: Industry, innovation and infrastructure SDG-12: Responsible consumption and production SDG-13: Climate action 2022-11-29T10:00:56Z 2022-11-29T10:00:56Z 2022-10-08 2022 Thesis * A2023 https://repository.up.ac.za/handle/2263/88528 https://doi.org/10.25403/UPresearchdata.21619044 en © 2022 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | UCTD Fumaric acid Lignocellulosic hydrolysate Bioprocessing Fermentation Rhizopus oryzae Engineering, built environment and information technology theses SDG-07 Engineering, built environment and information technology theses SDG-09 Engineering, built environment and information technology theses SDG-12 Engineering, built environment and information technology theses SDG-13 Rhizopus oryzae for fumaric acid production : continuous feed strategies to manipulate the metabolism |
| title | Rhizopus oryzae for fumaric acid production : continuous feed strategies to manipulate the metabolism |
| title_full | Rhizopus oryzae for fumaric acid production : continuous feed strategies to manipulate the metabolism |
| title_fullStr | Rhizopus oryzae for fumaric acid production : continuous feed strategies to manipulate the metabolism |
| title_full_unstemmed | Rhizopus oryzae for fumaric acid production : continuous feed strategies to manipulate the metabolism |
| title_short | Rhizopus oryzae for fumaric acid production : continuous feed strategies to manipulate the metabolism |
| title_sort | rhizopus oryzae for fumaric acid production continuous feed strategies to manipulate the metabolism |
| topic | UCTD Fumaric acid Lignocellulosic hydrolysate Bioprocessing Fermentation Rhizopus oryzae Engineering, built environment and information technology theses SDG-07 Engineering, built environment and information technology theses SDG-09 Engineering, built environment and information technology theses SDG-12 Engineering, built environment and information technology theses SDG-13 |
| url | https://repository.up.ac.za/handle/2263/88528 https://doi.org/10.25403/UPresearchdata.21619044 |