FAQs

In a laboratory, many different (incubator) shakers from different manufacturers may be found. These shakers may come with differently adjusted shaking diameters, e.g., 19 mm, 25 mm, 50 mm etc. Why does this matter?

To obtain reproducible results for your cultivations in shake flasks, MTPs and other shaken vessels, one crucial aspect is to keep the cultivation conditions constant. This includes for instance shake flask size, filling volume, and shaking frequency. All these parameters influence the oxygen supply (maximum oxygen transfer capacity, OTR max ) of the cultured cells. By keeping them constant, it is guaranteed that the oxygen supply is constant, and therefore, comparable, between experiments.

However, the shaking diameter (sometimes termed orbital diameter) also influences the oxygen supply (OTR max ) of the shaken vessel. For instance, an increase of the shaking diameter results in an increase of the OTR max; hence, the cultivated cells will receive more oxygen.

Now, if all cultivation conditions are kept constant, but the shaking diameter is neglected, cultivations on different shakers may cause deviating results due to differently adjusted shaking diameters. Therefore, before starting a cultivation, users should first check the shaking diameter of the applied shakers. Look here for a short and easy description of how to determine the shaking diameter of your lab shakers: Dr. Shakers helpful hint N°4.

If different shaking diameters are adjusted, there are two possibilities to solve this problem: either, the shaking diameter is adjusted to be the same for all shakers. For Kuhner shaking machines, the shaking diameter is user-adjustable. If the shaking diameter of your lab shaker is not adjustable, different shaking frequencies can be used; each adapted to the specific shaking diameter to result in the same OTR max for all applied shakers.

So, how do you know which shaking frequency needs to be adjusted? You can simply use the Kuhner OTR Calculator to find the correct combination of shaking diameter and shaking frequency.

More information and scientific data on the correlation between maximum oxygen transfer rate, shaking frequency and shaking diameter can be found in the Kuhner AppNote “Maximum oxygen transfer capacity in shake flasks” in the Kuhner Science Room.

Or check out this scientific publication:

Characterisation of the gas-liquid mass transfer in shaking bioreactors

Maier U, Buechs J. Biochem Eng J. (2001): Vol. 7, Issue 2, pp 99-106

https://doi.org/10.1016/S1369-703X(00)00107-8