CONSIDERATIONS IN DESIGNING A FERMENTATION MEDIA

(PICTURE TAKEN FROM NATALIE94.VOX.COM)

The fermentation media or the feedstock represents one of the most expensive and important component in any industrial fermentation process. The fermentation media is the raw ingredients that are going to be used by the fermenting microorganisms in the fermentor and be transformed into the valuable fermentation products. In the process some of the fermentation media itself will be used by the fermentation microorganisms to be converted into energy and some of the nutrients in the fermentation media will be transformed into the formation of biomass or new microbial cells.

NUTRITIONAL REQUIREMENTS OF FERMENTATION MEDIA
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The fermentation feedstock is going to be the substrate that will support the growth of the microorganisms in the fermentation process. The first thing that should be considered in choosing or designing the fermentation stock is that the fermentation stock must contain all the nutrients the microorganisms need for its growth.

What type of nutrients the microorganisms need depends on:

1 The choice of the microorganism used in the fermentation
2 Physiological status of the microorganisms.

In certain fermentations, the nutrient requirements are simple but there are microorganisms and especially in the cultivation of mammalian cells where the nutrient requirements may be stringent. In certain fastidious microorganisms certain vitamins, growth factors may need to be added. In the cultivation of mammalian and plant cells certain serums or hormones may have to be added.

The physiological state of the microorganisms in the fermentation process is important. While high carbon might be needed during the log growth phase, the input of carbon have to be controlled during the stationary phase especially in the production of secondary metabolites

In general all microorganisms need the following classes of nutrients:

1 Primary elements
2 Secondary or trace elements
3 Growth factors

The type elements needed may vary with the type and physiological status pf the microorganisms

In searching for the suitable fermentation stock biochemical and nutritional analyses of the feedstock material need to be determined first before other factors are considered


THE FINAL OBJECTIVE IS THE FERMENTATION PRODUCT
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Despite saying that the feedstock support the growth of the fermentation microorganisms but in the eyes of the fermentation technologists they see only that :

FERMENTATION FEEDSTOCK===> FERMENTATION PRODUCTS

They are always looking for processes that gives the highest conversion rate from substrate to products. They are also looking at the costs of producing the fermentation products.

So in choosing the fermentation feedstock they will have to consider the cost of production if using certain choice of fermentation feedstock!

ECONOMIC CONSIDERATIONS
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As in a simple assumption that it is the fermentation media or feedstock that will be converted to the fermentation products, the feedstock must be :
1 Easily available in large volume
2 Low costs

It is common therefor in any industrial fermentation the source of fermentation feedstock arise from agricultural or industrial wastes.

CHOOSING THE CHOICE OF WASTES AS FERMENTATION FEED
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Costs and availability are not the only considerations in the choice of a fermentation feedstock. There are other factors that need to be looked upon seriously

1 Agricultural or food industry wastes are often not of homogenous composition and its composition varies all the time
2 It is most likely that these sources of feedstock are not only contaminated by chemical, physical but also microbial contaminants
3 Nutrient quality or composition might be far from complete, ie not nutritionally balanced
4 They usually need to be pretreat before they are ready to be used as fermentation feedstock
5 They might cause complications during the actual fermentation process or downstream processing activities
6 Their product yield volume and quality might be low

PROBLEM AREAS IN FERMENTATION
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When choosing a particular fermentation feedstock, the two main problem areas created by the fermentation feedstock are in:

1 In the fermentor where the microbiological and biochemical transformations of the feedstock to product occurs
2 Down stream processing where separation, concentration and purification of the fermentation products from the fermentation broth occurs

Using a poor choice of fermentation feedstock will result in possibility of microbial contamination, foaming and mass transfer problems which will complicate the process and add costs to the production

I downstream processing extra efforts at additional costs are needed to extract and purify the products

IS IT WORTH IT?
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Some fermentation technologist even recommended using lab grade chemicals to be used as fermentation substrate to avoid complications in the fermentation process and increased cost in down stream processing. Of course on a large volume low value fermentation this is not really
posible......!!