Producción de conidios de Metarhizium robertsii en biorreactores de fermentación en medio sólido de escala laboratorio a piloto
Entomopathogenic fungi of the genus Metarhizium are important biological control agents. Regularly, the conidia of these fungi are produced in bag bioreactors that have limited capacity (1 kg of the substrate) and difficulties in monitoring and controlling culture conditions. Therefore, this type of...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2022 |
| País: | México |
| Institución: | Universidad Autónoma Metropolitana |
| Repositorio: | Repositorio Institucional de la UAM Iztapalapa |
| Idioma: | español |
| OAI Identifier: | oai:bindani.izt.uam.mx:k06987785 |
| Acceso en línea: | https://doi.org/10.24275/uami.k06987785 |
| Access Level: | acceso abierto |
| Palabra clave: | info:eu-repo/classification/LEM/Fermentación info:eu-repo/classification/LEM/Fermentation info:eu-repo/classification/LEM/Bioreactors info:eu-repo/classification/LEM/Biorreactores info:eu-repo/classification/cti/6 |
| Sumario: | Entomopathogenic fungi of the genus Metarhizium are important biological control agents. Regularly, the conidia of these fungi are produced in bag bioreactors that have limited capacity (1 kg of the substrate) and difficulties in monitoring and controlling culture conditions. Therefore, this type of process presents important variations in production, productivity, and quality of conidia which together with the high requirements of labor and area affect the viability of the process and the successful commercialization of the product. The limitations of the process make evident the need to establish new controlled processes that operate on a larger scale and allow obtaining high concentrations of conidia. For this reason, in this project, the production of conidia in bioreactors with different aeration mechanisms, as well as different operating conditions, was evaluated. Once the type of bioreactor and its operating conditions were selected, the manufacturing material of the experimental units was selected, and heat and mass transfer balances were made to estimate their dimensions. Finally, strategies were evaluated to improve the structure of the solid matrix (mechanical agitation and addition of texturizers), heat removal, microorganism growth, and conidia production. The packed column bioreactor with forced aeration was selected because it achieves productivity of viable conidia up to 1.8 times greater than that obtained with bag and tray bioreactors. In packed columns, heat removal by convective mechanisms allows maintaining a temperature ≤33 °C in the first 30 cm of height, which favors the growth and production of conidia of Metarhizium robertsii (Xoch 8.1). However, the increase in the diameter of the column significantly increases the packed density (up to 0.84 g/cm³ from 10 cm in diameter), hindering the transport of heat and mass, affecting, in turn, the microorganism growth and its conidia production. To avoid this phenomenon, the addition of plastic spherical packing to the culture bed improved the structure of the solid matrix (decreasing the packed density), gas exchange, and heat removal. The above allows reaching a conidia production (1.23 × 10⁹ conidia/gdm) similar to those obtained in laboratory-scale bioreactors (from 1.23 to 1.44 × 10⁹ conidia/gdm) was obtained. Under the conditions tested, the packed column bioreactor can reach an operating volume of 47.71 L (∼25 kgdm) to produce ∼3.1 × 10¹³ conidia per batch. This packed column could form part of a modular bioreactor that operates in an industrially controlled process, with higher production yields and lower labor and area requirements than the traditional bag bioreactor process. |
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