Revealing Microbial Fermentation: Shake Bottle Culture vs. Tank Culture (Differential Analysis, Balance Method)
They each have unique advantages and limitations, which have different impacts on the understanding and control of the fermentation process.
Shake bottle cultivation is widely used in basic research and teaching due to its easy operation and low cost.
However, when the fermentation parameters obtained under shake flask cultivation conditions are applied to large-scale tank cultivation, inconsistencies in the results often occur.
This difference may be due to various factors, including dissolved oxygen conditions, CO2 concentration, mechanical damage, etc.
The difference between shake flask culture and jar culture
1. Differences in dissolved oxygen: Shake flask culture: Oxygen is transferred through bottle stoppers or breathable membranes, which are greatly affected by the surrounding environment.
Tank cultivation: Ventilation is carried out through an air system, and the dissolved oxygen coefficient Kd shows significant differences between shake flask fermentation and fermentation tanks.
2. Differences in CO2 concentration: The CO2 produced during microbial fermentation has a significant impact on bacterial growth and product synthesis.
Shake bottle culture: Under normal pressure, the concentration of CO2 is relatively low. Can culture: Under positive pressure, the concentration of CO2 is high, which affects the growth of bacterial cells and product synthesis.
3. Differences in mechanical damage: Shake bottle culture: The bacterial cells suffer less mechanical damage and are mainly affected by liquid impact or sliding along the bottle wall.
Tank cultivation: Factors such as shear force of the stirring blades and stirring time can cause significant mechanical damage to the bacterial cells.
4. Other influencing factors: pH control: Tank cultivation can achieve more stable pH control. Pressure: Shake the bottle at normal pressure, while tank cultivation may be carried out at different pressures.
Feeding system: Tank culture can perform feeding operations, while shake bottle culture usually does not have this condition.
Methods to reduce the difference between shake bottle and tank fermentation
1. Increase the Kd value and dissolved oxygen level of the shaking bottle: Increase the speed of the shaking bottle machine to simulate the high dissolved oxygen environment in tank culture.
2. Reduce the amount of culture medium: Pay attention to water evaporation to minimize the impact of reduced culture medium on experimental results.
3. Introduce sterile air or oxygen: Directly introduce sterile air or oxygen into the shaking bottle to increase the dissolved oxygen level.
4. Simulate mechanical stirring: Add glass beads to a shaking bottle to simulate mechanical stirring in a fermentation tank and study the differences caused by stirring.
Common methods for balancing influencing factors
1. Use a baffle: Attach a baffle to the shaking bottle to simulate damage to the mycelium during fermentation in a tank.
2. Choose a suitable mixer: Use a mixer with lower shear force, such as a propeller or a disc impeller worm gear mixer.
3. Adjust the stirring speed and time: Slow down the stirring speed appropriately and intermittently stir to reduce bacterial damage.
4. Increase the viscosity of the fermentation broth: Without affecting the Kd value or dissolved oxygen, increase the viscosity of the fermentation broth appropriately to reduce the impact caused by stirring.
