What is oxygen transfer efficiency (OTR)?
The oxygen transfer efficiency refers to the efficiency with which oxygen is transferred from the atmosphere to the liquid. The higher the OTR value, the higher the oxygen transfer efficiency.
1. The influence of amplitude and speed
Both of these factors affect the mixing of the medium in the culture flask. The better the mixing effect, the better the oxygen transfer rate (OTR). Following these guidelines, the most suitable amplitude and speed can be selected. Generally speaking, choosing 25mm amplitude can be used as a universal amplitude for all cultures.
Because of this, the amplitude of most shakers is 25 mm. In some applications, if there are special restrictions on oxygen delivery/cell growth, some special amplitudes may be selected.
2. Bacteria, yeast and fungus culture:
The oxygen transfer efficiency in the shake flask is much lower than that of the bioreactor. In most cases, oxygen transfer may be the limiting factor for shake flask culture. The amplitude is related to the size of the conical flask: use large amplitude for large flasks. Suggest:
1. 25mm amplitude is applied to conical flasks from 25ml to 2L
2. The 50mm amplitude is applied to the conical flasks of 2 to 5 liters
3. Cell culture:
However, mammalian cell culture requires relatively low oxygen, and lower power input is sufficient.
1. For a 250mL shake flask, sufficient oxygen transmission can be provided in a wide range of amplitude and vibration speed (20-60mm amplitude; 100-300rpm).
2. If the flask with a larger diameter (Fernbach flask) is recommended to use 50 mm amplitude
3. Use disposable culture bags, 50mm amplitude is recommended.
4. Microplate and deep well plate:
There are two different methods for microplates and deep well plates to get the maximum oxygen transfer!
1. Use 50mm amplitude, and the speed should not be lower than 250rpm
2. Use 3mm amplitude and rotate speed at 800-1000rpm
In many cases, even if a reasonable amplitude is selected, it may not be able to increase the amount of biological culture, because the increase in the amount of culture will be affected by many factors. Example: If one or two of the ten factors are not ideal, then no matter how good the other factors are, the growth of the culture volume will be limited, or it can be said that if the limiting factor of the culture volume is only oxygen transfer, the amplitude is correct The choice will get a significant increase in the incubator. For example, if the carbon source is a limiting factor, no matter how good the oxygen transfer effect is, the ideal culture volume will not be achieved.