WHICH IS BETTER; ONE BIG FERMENTOR OR MANY SMALL FERMENTORS?

When intending to acquire acquire fermentors, with our limited financial constraint, we are often faced with the choice of either buying one unit of a large fermentor or buying a few smaller size fermentors. If you are already clear with your purpose and objective of what type of studies or scale of fermentation you want to carry out, then it is not a problem at all. The headache confronting the buyer who have to made the choice are those that are often with no fermentation experience or just a novice who is starting to learn the rudiments of fermentation using the fermentor the first time.

Sad to say it is not really wise to listen to the sales people trying to sell and dump their fermentors to you. It is better in any instance before buying a big or small fermentors to ask those people or colleagues who have been working with fermentors over a number of years. Buying fermentors is a capital investment, and in many cases the buyers end up buying fermentors that are over designed or under desogned for his purpose. In most cases through the author's personal experience visiting a number of fermentation laboratories that ultimately the fermentors bought are just expensive white elephants sitting in one corner of the laboratory collecting dusts.

Of course, buying a very large fermentor is a prestige for the person. even though many might not know the person who bought the fermentor might be under using the fermentor!

THE OBJECTIVE OF BUYING THE FERMENTOR
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Questions that you will find useful in making the choice between big and small fermentors are:

1 What sort of fermentation studies are you carrying out? What are the parameters and operating regimes you are studying?

2 What is the level or scale of studies are you involving? Is it some basic fermentation studies or are you looking for scale up works? Is the scale up exercise you are looking for significant in magnitude to require a pilot scale fermentor , for example.

3 What is the volume of fermentation broth that you are really looking? Are you interested in producing large volume of broth for test samplings or for complete analyses?


Any fermentation studies involving bioreactors must pass through various stages of study. In the earlier phase of studies where crude data are needed, or not so detailed monitoring of the fermentation process are required, even table top fermentors may be avoided. Sometimes shake flasks and petri dishes studies suffices at that level

But at the level of using sensors and monitoring the fermentation using liquid broth fermentors are needed. Normal table top or teaching and research fermentors should suffice. A fermentor capacity around 3 litres or less working volume would suffice. There is no need for larger fermentors at this stage of the study. Investing in larger fermentors would not yield the level of data which is not yielded by the smaller fermentors. In fact you waste more fermentation broth and poorer mass transfers.......and of course more costly!

In buying small fermentors at this stage you can get a number of small fermentors for the price of one big fermentor without significantly affecting your data or results. With such a high number of fermentors you can carry out more fermentation runs at any one time or do variability studoes such as different mixing rate in one go! Your fermentation results too would be statistically more significant!

Fermentors being mechanical and electrical equipment can and do suffer from breakdowns. With so many fermentors at disposal there is no problem of interchanging parts or even salvaging parts that can be used in the other fermentors. This will guarantee your fermentation lab will be operating for decades

SUPPORT SERVICES
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Using small fermentors will only need the normal microbiology laboratory environment. There is no need to have special large air compressors or high pressure water pumps or even special electrical supply. All these additions will incur additional costs. Is your laboratory up to it?