( ByBrian ...)FERMENTATION BASICS

By Brian Pumphrey New Brunswick Scientific (UK) Ltd and Christian Julien New Brunswick Scientific Benelux BV (The Netherlands) May 1996

Fermentation is the term used by microbiologists to describe any process for the production of a product by means of the mass culture of a microorganism.

The product can either be:
1. The cell itself: referred to as biomass production.
2. A microorganisms own metabolite: referred to as a product from a natural or genetically improved strain. See Table 1.
3. A microorganisms foreign product: referred to as a product from recombinant DNA technology or genetically engineered strain, i.e. recombinant strain. See Table 2.

2.1. Classification of microorganisms
The kingdom Protista comprises unicellular organisms capable of self duplication or of directing their own replication. Prokaryotes do not possess a true nucleus or a nuclear membrane, whereas eukaryotes have a nucleus enclosed within a distinct nuclear membrane. The non-cellular protists do not undergo self-replication, instead they direct their reproduction within another cell termed the host.

Cyanobacteria (blue-green algae) in Fig.1 have been classified as a separate group of microorganisms, although they are frequently considered to be included with other bacteria. Fungi may be subdivided into lower fungi as well as slime moulds and higher fungi which comprises yeasts. Yeasts are free-living, single cells, unlike fungi, which they closely resemble. Protozoa are free-living, minute organisms, which although not generally employed for biotechnological processes have been included for completeness. Myxomycota, commonly known as slime moulds (or slime fungi) are wide
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