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Continuous succinic acid fermentation using immobilised Actinobacillus succinogenes
Dissertation (MEng)--University of Pretoria, 2013.
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| Format: | Thesis |
| Language: | English |
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University of Pretoria
2014
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| _version_ | 1867613575162363904 |
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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 | © 2013 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 | Dissertation (MEng)--University of Pretoria, 2013. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/40818 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:38:19.381Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2014 |
| publishDateRange | 2014 |
| publishDateSort | 2014 |
| 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:2263/40818 Continuous succinic acid fermentation using immobilised Actinobacillus succinogenes Nicol, Willie karishma.maharaj@gmail.com Maharaj, Karishma Succinic acid Actinobacillus succinogenes Continuous fermentation Biofilm Pyruvate formate lyase Pyruvate dehydrogenase UCTD Dissertation (MEng)--University of Pretoria, 2013. Actinobacillus succinogenes cells were grown on Poraver® support particles in a packed-bed reactor. Dilution rates (D) of 0.054–0.72 h-1 were investigated. Glucose was used as substrate. CO2 (g) was bubbled into a complex medium to satisfy the fixation requirements and maintain anaerobic conditions. At D ≥ 0.31 h-1, an initial glucose concentration of 35 g.L-1 was used; at lower dilution rates, this was increased to 60 g.L-1 in order to avoid substrate limitations. By-product formation included acetic and formic acids. A maximum productivity of 10.7 g.L-1 was obtained at D = 0.7 h-1. It was found that the system provided repeatable results at a given D. The longest steady state period was maintained for about 97 h at D = 0.31 h-1. Steady state stability was maintained for > 72 h at D < 0.31 h-1. For periods longer than 75 h, however, inhibitory acid titres resulted in a gradual decline in productivity. At higher dilution rates, long-term stability could not be maintained. The low acid titres produced significant biofilm sloughing following aggressive biofilm growth, resulting in oscillatory system behaviour. For fermentation times < 115 h, the dilution rate was secondary to the attachment area in determining the total biomass at steady state. Total biomass values were then used to determine specific rates. A clear trend was observed, with the specific glucose consumption rate, and specific acid production rates, increasing with increasing D. This was explained by assuming a maintenance-driven system at all Ds studied. A product analysis indicated that at ΔS < 15 g.L-1, pyruvate formate lyase was the preferred oxidative route. A shift to the pyruvate dehydrogenase pathway occurred at higher ΔS values, so that the highest YSS values obtained exceeded 0.85 g.g-1. A decrease in C3 by-product formation resulted in high YSS values being maintained, indicating an additional, unknown source of nicotinamide adenine dinucleotide (NADH). It is recommended that any process utilising immobilised A. succinogenes cells should operate at an intermediate D, in order to maintain long-term reactor stability, high productivities and good yields. gm2014 Chemical Engineering unrestricted 2014-07-17T12:08:28Z 2014-07-17T12:08:28Z 2014-04-08 2013 Dissertation Maharaj, K 2013, Continuous succinic acid fermentation using immobilised Actinobacillus succinogenes, MEng dissertation, University of Pretoria, Pretoria, viewed yymmdd <http://hdl.handle.net/2263/40818> E14/4/287/gm http://hdl.handle.net/2263/40818 en © 2013 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 | Succinic acid Actinobacillus succinogenes Continuous fermentation Biofilm Pyruvate formate lyase Pyruvate dehydrogenase UCTD Continuous succinic acid fermentation using immobilised Actinobacillus succinogenes |
| title | Continuous succinic acid fermentation using immobilised Actinobacillus succinogenes |
| title_full | Continuous succinic acid fermentation using immobilised Actinobacillus succinogenes |
| title_fullStr | Continuous succinic acid fermentation using immobilised Actinobacillus succinogenes |
| title_full_unstemmed | Continuous succinic acid fermentation using immobilised Actinobacillus succinogenes |
| title_short | Continuous succinic acid fermentation using immobilised Actinobacillus succinogenes |
| title_sort | continuous succinic acid fermentation using immobilised actinobacillus succinogenes |
| topic | Succinic acid Actinobacillus succinogenes Continuous fermentation Biofilm Pyruvate formate lyase Pyruvate dehydrogenase UCTD |
| url | http://hdl.handle.net/2263/40818 |