Publication: Estudio de las condiciones fluido-dinámicas en cultivos bacterianos en tanque agitado
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2018-08-24
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Universidad Complutense de Madrid
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Abstract
El desarrollo de bioprocesos ha experimentado un enorme crecimiento en las últimas décadas. Las ventajas que presentan los procesos realizados con células vivas y sus enzimas, utilizados como biocatalizadores, junto con las cada vez más exigentes restricciones energéticas y de emisiones contaminantes promovidas por las instituciones internacionales, han centrado la atención de la comunidad científica en esta área, recibiendo un gran impulso por parte de organismos públicos y privados. Dentro del elevado número de variables que hay que considerar en el cambio de escala de un bioproceso y su puesta en marcha, el estudio de la influencia de las condiciones fluido-dinámicas es uno de los aspectos más relevantes, ya que determina las velocidades relativas de un conjunto de fenómenos claves para asegurar el comportamiento deseado de los procesos que se pretende llevar a cabo. La fluido-dinámica condiciona no sólo el transporte de materia entre fases en los reactores, tanto a nivel de contacto entre las fases líquida y sólida (células), sino también el transporte gas-líquido cuando alguno de los sustratos se encuentra en fase gas. Además, determinadas condiciones de agitación pueden comprometer seriamente la integridad del biocatalizador, como ocurre en los sistemas biológicos con células completas, donde pueden inducirse situaciones de estrés hidrodinámico, debido a la colisión entre las células y los elementos sólidos del reactor o, simplemente, por el esfuerzo cortante que se origina con la agitación. También puede inducirse un estrés oxidativo, que se produce en sistemas aerobios por un desequilibrio entre el exceso de especies reactivas del oxígeno y la capacidad celular para destoxificar el medio...
The development of the bioprocesses has experienced a huge growth in the latter decades. The known advantages of the use of enzymes or whole cells as biocatalysts, coupled with the increasingly stringent energy constraints and the new legal regulations promoted by the international organisms to reduce the pollutant emissions, had focused the attention of the scientific community to this area. Consequently, the applied biotechnology has received a great boost by the public and private institutions. One of the key steps in the development and the start-up of a bioprocess is the scaling-up, which involves the consideration of a large number of variables. Within this field, the study of the influence of fluid dynamic conditions is one of the most relevant aspects, because it determines the relative rates of a set of crucial phenomena in order to ensure the desired behavior of the transformations to be carried out. The fluid dynamic influences the mass transfer rate in the bioreactors, both the contact between the liquid and solid phases (whole cells), and also the gas-liquid transport when one of the substrates is in the gas stream. Moreover, several operational conditions can seriously compromise the biocatalyst integrity, as it occurs in the biological systems with growing cells, due to the collisions between the cells and the solid parts of the reactor or the shear tension produced by the agitation. In addition, if the bioprocess is carried out under aerobic conditions, an oxidative stress can be induced by disequilibrium between the excess of oxygen reactive species and the cell capacity to detoxify the medium...
The development of the bioprocesses has experienced a huge growth in the latter decades. The known advantages of the use of enzymes or whole cells as biocatalysts, coupled with the increasingly stringent energy constraints and the new legal regulations promoted by the international organisms to reduce the pollutant emissions, had focused the attention of the scientific community to this area. Consequently, the applied biotechnology has received a great boost by the public and private institutions. One of the key steps in the development and the start-up of a bioprocess is the scaling-up, which involves the consideration of a large number of variables. Within this field, the study of the influence of fluid dynamic conditions is one of the most relevant aspects, because it determines the relative rates of a set of crucial phenomena in order to ensure the desired behavior of the transformations to be carried out. The fluid dynamic influences the mass transfer rate in the bioreactors, both the contact between the liquid and solid phases (whole cells), and also the gas-liquid transport when one of the substrates is in the gas stream. Moreover, several operational conditions can seriously compromise the biocatalyst integrity, as it occurs in the biological systems with growing cells, due to the collisions between the cells and the solid parts of the reactor or the shear tension produced by the agitation. In addition, if the bioprocess is carried out under aerobic conditions, an oxidative stress can be induced by disequilibrium between the excess of oxygen reactive species and the cell capacity to detoxify the medium...
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Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Químicas, Departamento de Ingeniería Química, leída el 16-06-2017