ABSTRACT
A reactor is a confined space used for transformation of reacting entities from one chemical form into another in a certain time period. This broad definition of the reactor space is equally applicable to bioreactors where the chemical transformation is achieved with assistance from either a living and growing population of microbial species or a biocatalyst in its pure or crude form, in a dissolved condition or in an immobilized form on a suitable support. The objective of the bioreactor could be conversion of a complex raw material into a value-added product, as in fermentation of molasses into alcohol or into relatively expensive drug intermediates or antibiotics such as penicillin, which may have to undergo further derivatization into semisynthetic drugs. A growing mould or bacterial colony in immobilized form on a solid support, wherein the nutrient carrying medium flows over the colony is another form of bioreactor. The medium can be well defined as that encountered in enzymatically catalyzed isomerization of glucose or separation of dl-amino acids mixtures, and it can be very complex, as in fermentation of corn syrup. In the former case the reactor resembles the packed bed operation in the conventional chemical industry.
