Data Spotlight

Influence of Shake Flask Closures on Biomass Yield and Oxygen Consumption in E. coli Cultures

Background

The choice of closure is essential, as it impacts the rate of oxygen entering the flask and thus impacts oxygen-dependent cellular events like biomass production. Historically, cotton plugs have been used for covering shake flasks due to their ease and low cost while offering high oxygen transfer into one's culture. While having these advantages, they are also known to have higher contamination risks than the more advanced closure types, such as silicone. 

It is important for any bioprocess design to balance ease of use, cost, and the need for optimal growth conditions while presenting only a minimal risk to the cells.

Different Closure Types on Biomass and Dissolved Oxygen-1

Cultures are grown under the same conditions while being closed with different types of conventional lids to test if these different types of closure influence microbial growth and oxygen consumption of E. coli eGFP Gold.

Different Closure Types - Metal Cotton Silicone

Materials & Methods

Cultures were performed on LB medium in 250 mL Erlenmeyer shake flasks with a filling volume of 10% and shaken at 24°C and 200 rpm. All cultures grew under the same conditions. Three closures types were tested: metal cap, sterilized cotton ball, and silicone. Dissolved oxygen (DO) and biomass measurement under standard settings were analyzed by the Multi-Parameter Sensor (MPS) and Dissolved Oxygen Sensor Pills

Conclusion

There was a slight variation in dissolved oxygen levels between the three closure types of the shake flasks under 10% filling volume. Despite this minor variation in the levels of dissolved oxygen, the biomass concentration of flasks closed with cotton balls is slightly higher than those closed by a metal cap or silicone. Therefore, it is essential to understand the different factors involved during closure selection to that the objectives of the designed bioprocess can be achieved with the assurance of providing ideal conditions for growth and minimal risk for the culture.

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From Estimation To High-Resolution Growth Curves

Cell Growth Quantifier (CGQ)
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Customer Success Stories

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“Incorporating SBI’s pH and DO flow cells into our system removed the need for manual sampling, saving us time, reducing the risk of contamination, and providing information on how the cells are growing even when we are not in the lab. With availability of this more detailed view of our culture, we can make informed improvements to our cell expansion process.”

-Kitana Manivone Kaiphanliam (Washington State University)
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