PREPARING THE FERMENTOR FOR STERILIZATIONS

This discussion will be using a laboratory scale fermentor as the example.

After the fermentor vessel has been thoroughly cleaned, rinsed and dried, it is ready to be prepared for sterilization in the autoclave. The following main steps should be taken:

(NOTE: DURING THESE STEPS EXTRA CAUTION MUST BE TAKEN TO AVOID DAMAGES)

1The vessel seals should be removed and lightly greased with silicone grease
2Fill up the vessel with the desired fermentation medium. Ensure that about a headspace of
about 20% of the vessel volume be retained
3Replaced the top plate onto the vessel and clamp and tighten all bolts
4 Insert the relevant electrodes
5 Do the same for all other tubing connections
6 All electrodes terminals capped to avoid water
7 Ensure one opening filtered to allow air to escape

DETAILS OF THE ABOVE STEPS
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Normally lab scale fermentors are small vessels which have a glass body with a glass or stainless steel top plates. Since we are dealing with glass, the risk of the fermentor being accidently mishandled and broken is high. This even applies especially to the glass ph electrodes which usually comes with a glass casing.

Be sure to handle the glass body tightly and properly. Rest the glass body slowly and carefully. Make sure the glass body is rested or stand in a very stable position so as not to roll or move accidently

The glass electrodes must be placed in a special tray with soft padding to be easily transported around. A clean tray should also be used to keep all the nuts, screws, clips, tubings, filters that belong to the fermentor in questioned.

Ensure that silicone grease is used to seal the various O-rings. This grease is suitable because it can withstand high temperature and vacuum. Make sure not to over grease as it may create problems of fittings bungs or rubber stoppers (if used)

When filling the fermentor with the fermentation media, it is more convenient to do it before placing the top plate. After filling to the desired volume, place the top plate onto the body of the fermentor.

Tighten the bolts and nuts slowly and gently. Ensure opposing nuts are tightened simultaneously. Do not over tighten the nut or blocker because it will damage the fermenter threads and the O- rings

Insert the relevant electrodes slowly and properly aligned. It is better to wet the e;ectrodes to improve the lubrication and make the insertion easier. At the end of inserting the electrode tighten the nuts slowly and gently

There are various type of tubing sizes to be used in setting up the fermentor. Ensure the tubings used are of tygon type or silicone rubber. If older tubings are to be used ensure that its not brittle or damaged. Cut of the tips of damaged tubings before making connections. Ensure that the ends of the tubings are clipped properly to maintain aseptic integrity

Tubings used for water jacket should be pressure tubings. Do not lock up the male nut into the female nuts as it might lead to high pressure developing during sterilization leading to breakage

Cap or cover all terminal ends or port holes ends with aluminium to prevent wetting

LAST CHECKING
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This is the most important final step before the fermentor enters the autoclave. Ensure all outlets are tightened
Ensure there is one port hole or outlet opened to let air escape
Ensure all tubes or insertions correctly positioned

...and may God bless you!