1. General

1.1 Selection and sizing principles

• The type of bioreactor to be used depends on the number of phases involved in the bioreaction: a single liquid phase, or a gas phase dispersed in a liquid phase (in the case of aerobic cultures), or a solid phase dispersed in a liquid phase (in the case of immobilized enzymes, for example).

  It should be noted that, as micro-organisms are smaller than 20 µm in size and have a density very close to that of the culture media, suspensions of micro-organisms in culture media are considered to be a pseudo-homogeneous liquid phase. Of course, this assumption is no longer valid if the micro-organisms tend to agglomerate to form flocs (yeast) or pellets (filamentous fungi).

• ...