CHOOSING THE RIGHT FERMENTOR FOR YOUR NEEDS!

There are many types of people who are interested in carrying out different fermentation studies, and there are as many types of fermentors available from the market. It has never been a simple and easy choice to choose and buy a fermentor for your needs. Sometimes buying a fermentor is akin to buying your first car...you might in the end concluded you bought the 'wrong' fermentor based on your inexperience and wrong advices given by your so called ' fermentation expert ' colleagues!

There are several factors that influence in the choice of your fermentor;

1 PRICE
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Fermentors are generally very expensive capital equipments. A good simple laboratory fermentor easily costs as much as a small car! So, unless you have a lot of money to spend it's better to buy a fermentor that is within your economic range but still able to fulfil your fermentation needs. Big and sophisticated fermentors or famous branded fermentors are expensive.

So if your money is quite a limiting range it is better to go for a standard fermentor that is equipped with the basic sensors and controllers. Do not go for the advanced andmore sophisticated range. Even though it is more impressive but the additional benefits is not worth the extra costs!

Go for the well known reliable brands that is widely used in various laboratories and do try to get the comments about that brand from other users of the fermentor. Personally, I have always been impressed by the New Brunswick fermentors which in my opinion are good value for money and they are the reliable 'work horses' of fermentation.

Somehow I have always have preferences for the analogue controlled fermentors compared to the digital automatic advance models. I mean things are fine with the advanced fermentor models until breakdown sets in.

SIZE OF FERMENTOR
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The general rule about fermentor is that the bigger the fermentors, the more expensive they are. Of course it is unavoidable to buy large fermentors for pilot scale and production scale fermentation. If however, we are intending to do basic research or for teaching, the fermentors recommended should be small fermentors of 5 litres capacity or less. It is more easy to manipulate and cheaper to operate.

I find that there is no difference in the results of fermentation studies carried by fermentors of 2 litres to 10 litres study. In fact by using larger fermentors we need to use more fermentation media, aeration compared to using smaller fermentors.

It is far more better instead of investing in one large fermentors we opt for a number of smaller identical fermentors. At least we can do variation experiments or replicates within the same time!

TYPE OF FERMENTATION TO BE CARRIED OUT
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Most fermentors offered in the market are basically the "standard" design or called the Continuous Stirred Tank Reactor or CSTR . These CSTRs are usually in the form of cylindrical tank equipped with a stirrer with standard electrodes such as ph, dissolved oxygen and temperature probes. It is usually equipped with air spargers.

These CSTRs are more designed for general aerobic fermentation as indicated by presence of spargers and dissolved oxygen probe. It is also meant for pure culture fermentations reflected by its strong aseptic design.

This model is not specific for anaerobic fermentation or those involving open and septic fermentations.

This is not trying to say that these fermentors are unsuitable for anaerobic or septic fermentations. It merely means that using these fermentors is a waste of extra costs incurred as they are not required. Perhaps it only makes the manufacturers and sales people happy!

FERMENTORS FOR RESEARCH AND TEACHING
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Fermentors used for research and teaching normally consist of small size bench top fermentors with working volume of between 2 to 5 litres.

Teaching fermentors are usually small fermentor with the basic sensors such as ph, temperature and dissolved oxygen probes. Usually these fermentors are sterilized in autoclaves as they are not often equipped with in situ sterilization facilities. They are usually with glass body and maybe with a stainless steel top plate

Research fermentors are about the same as the teaching fermentors but they may be bigger of up to 50 or even 100 litres capacity. Usually research fermentors consist of a range of fermentors of various sizes to accomodate some basic scale up studies.

Research fermentors may be equipped with additional probes and sensors

COMMON MISTAKES IN BUYING A FERMENTOR
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One of the most common mistakes in buying a small fermentor with non ' in situ' sterilization facilities is that no considerations are given for suitable autoclave provisions for the fermentor. Some discovered to late that they have bought fermentors that could not fit the autoclave chamber! Or that the fermentors can only fit the autoclave only by doing physical calistenics for the fermentor in order to fit the autoclave! This is dangerous and might result in poor sterilizations of the fermentor

(MORE WILL BE DISCUSSED IN SECTIONS ON FACILITIES FOR FERMENTATION LABORATORY/PLANT)