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Kuhner Seminars

Since 2002, Kuhner AG has successfully held courses about cultivation in shaken bioreactors (shake flasks, microtiter plates etc.). We can also provide further education and training for your staff if requested.

Frequently asked questions addressed in our seminars include: 

  • What are the fermentation conditions in a shake flask/MTP?
  • How do I cultivate in a shake flask without oxygen limitation?
  • Baffles: yes or no?
  • Why doesn’t the scale-up work in stirred bioreactors?
  • Which stoppers/adhesive foils are suitable for shake flasks /MTP?
  • Why are the fermentation results not reproducible?
Dr. Shaker

These and other issues are discussed and backed up with scientific evidence. We can also provide seminars on specific themes of your choice.

If you would like to be notified about future seminars, please contact us.

Kuhner seminars
Seminarraum Mas Boada


What is the shaking diameter?

The shaking table of an orbital shaker moves in a circle. The diameter of this circle is called the “shaking diameter”.

Most commonly used diameters are

  • 12.5 mm (ca ½ inch)
  • 25 mm (ca. 1 inch)
  • 50 mm (ca. 2 inch).

On all Kuhner shakers the orbital movement can be changed at any time.

Do different diameters affect the cultivation? 

Yes. The shaking diameter is a key factor for the cultivating conditions in a shaken bioreactor. Given the same speed; the bigger the shaking diameter, the better the oxygen transfer rate inside the culture. This also applies to microtiter plates.

Do you need a smaller shaking diameter when working with microtiter plates (e.g. 3mm)?

No. Microtiter plates can also be shaken with a larger diameter; the smaller the diameter, the faster the speed required (e.g. 700 rpm with 3mm). When choosing a larger diameter such as 50mm, a speed of 250 rpm may be enough to guarantee proper mixing and oxygen transfer.

What is the sheer sensitivity in a shaken bioreactor?

In a shaken bioreactor the mechanical stress on the cells is usually considerably less than in a stirred system. In a stirred bioreactor there are two stress effects: on the one hand you have small eddies near the impeller blades and on the other hand, small bubbles burst on the liquid surface because the vessel is sparged from the bottom. In a shaken bioreactor there is surface aeration and the shaking movement gives uniform mixing without any local power inputs

Does the shaker motor heat the shaking table?

No. Kuhner shakers have a unique drive system emitting less than 10 watts of heat.

How about shaking light sensitive medium?

Kuhner has the option of blackened windows to prevent light affecting your medium.

How do I reduce evaporation from flasks/MTP?

The smaller the volume and the longer the fermentation time, the more the evaporation rate affects your cultivation. Evaporation can be reduced by using special lids, stoppers, adhesive foils etc. One example is the Duetz system for microtiter plates. It is also necessary to humidify the incubator chamber.

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