Análisis metabólico y termodinámico in silico para la biosíntesis de ácido 3-indolacético (AIA) a partir de glicerol en Azospirillum brasilense
In this work the bioconversion of glycerol to indol acetic acid (IAA) is proposed using Azospirillum brasilense as biocatalyst, a bacteria with a natural capacity to produce IAA. In the beginning, a black box model was defined to evaluate the thermodynamic feasibility for the anaerobic conversion of...
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| Tipo de documento: | dissertação |
| Estado: | Versión aceptada para publicación |
| Data de publicação: | 2019 |
| País: | Colombia |
| Recursos: | Universidad Nacional de Colombia |
| Repositório: | Repositorio UN |
| Idioma: | espanhol |
| OAI Identifier: | oai:repositorio.unal.edu.co:unal/76125 |
| Acesso em linha: | https://repositorio.unal.edu.co/handle/unal/76125 |
| Access Level: | Acceso aberto |
| Palavra-chave: | 660 - Ingeniería química Ácido 3-indolacético Análisis de flujos metabólicos Azospirillum brasilense Glicerol Termodinámica Indol acetic acid Flux balance analysis Glycerol thermodynamic |
| Resumo: | In this work the bioconversion of glycerol to indol acetic acid (IAA) is proposed using Azospirillum brasilense as biocatalyst, a bacteria with a natural capacity to produce IAA. In the beginning, a black box model was defined to evaluate the thermodynamic feasibility for the anaerobic conversion of IAA from glycerol (-ΔrG°’ = 387.3 kJ molAIA-1 ), however, it was not possible to reproduce this scenario by a metabolic model built for A. brasilense (296 reactions and 260 metabolites). From this former result, it was decided to change ammonium by nitrate as the nitrogen source, nevertheless, the problem at the metabolic level continued despite it has a higher Gibbs free energy available (-ΔrG°’ = 981 kJ mol AIA-1 ). From the analysis of the above two scenarios the following was found: 1. There was a limitation to harvest biologically uselful Gibbs free energy (mainly at the level of ATP production), and 2. There was a need to fix CO2 at the level of IAA precursors to compensate for the excess of electrons per carbon atom in glycerol with respect to IAA. Thus, an alternative set of catabolic reactions was proposed using oxygen, NO3 - /NO2 - or ethanol as alternative acceptors allowing the solution of the identified metabolic hitches, in addition to the incorportation of the Wood-Ljungdahl pathway to fix CO2 under anaerobic conditions. A new thermodynamic analysis was carried out for these new possibilities in order to evaluate different criteria and suggest the best scenario for IAA production. It was found that using nitrate as both nitrogen source and electron acceptor a yield slightly lower than with oxygen was obtained. This may be compensated by reducing operation costs such as tank gassing and base consumption. |
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