Estudio de las condiciones fluido-dinámicas en cultivos bacterianos en tanque agitado

Abstract

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...