Studies carried out in shake flask shows a good yield of product, however upon growth in a bioreactor, the yield of the compound decreases. Also the biomass is reduced. The conditions in reactor were maintained same like flask. Does any one experience a similar condition? Can anyone suggest anything
What kind of bioreactor are you using? What the conditions of cultivation?You need pay attention with oxygen transfer and shear rate.
I am using a 2.4 L Bioengineering reactor (Switzerland) with a working volume of 1.2 L. temperature 30oC, 200 rpm, un-aerated conditions
If the microrganism are aerobic, I think the problem is oxygen transfer. You could test with aerated conditions and more agitation.
Basically, you have to provide an environment similar to your shake flask if you want to achieve similar yields. Unfortunately, fluid dynamics in a bioreactor are very different from your shake flask. So, to commence you should check the oxygen demand, maximum allowable shear stress, pH range, etc for your culture and then you start with your scale up.
Later you can optimize your bioreactor process by changing spargers, impellers or feeding strategy.
many things in bioreactor are different from shake flask.As Marcel pointed aeration is one factor which may cause problems. If you are using bioreactor with low concentration of substrate for example equal to the amount you use in shake flasks it is normal to get lower yield but as you start working in high concentration it improves.
If the results do not enhance after increase in substrate concentration,you need to double check the design of your reactor with a special focus on any device responsible for agitation in that reactor
Best Regards
Sepideh
Hi Rothangmawi, when you use un-aerated systems you may pay attention on mixing times and energy dissipation.
Good luck, Thomas
Hi,
What about volume and concentration of seed culture that you used for innoculation? Seed must have adequate cfu per ml of volume. Also period of cultivation in reactor and shake flask is different and it is nessesary to draw a growth curve plot for determining of the time of process terminatin.
It is but natural. As you scale up you use different modes of operation involving energy consumption and it results in making small adjustments to your already optimised parameters. Sometime back some body had asked a similar question, and there I had pointed out that even the initial energy of the system is different (which is called as the enthalpy), from your previous size. All these matters as the enthalpy change in a larger size is following a different pattern than the smaller one. However, if you wish to maintain the same yield (here it must be defined as a function of residual substrate concentration) then change or adjust or fine tune your previous observations.
Dear Victoria,
ıf your production is anaerobic, as Thomas said, tm (mıxıng tıme) is considerable. you should check tm of two systems and make sure they are equal. ıf not, you should speed up/down your agitation accordingly. Please remember, 200 rpm in a shake flask ıs not equal to 200 rpm ın bıoreactor. As Sepideh and Alexander said, be sure that your cells do not get harm by agitation which causes shear stress. You should calculate the shear stress, too.
Reactor geometry ıs very ımportant too. Maybe you should buy a new impeller type if your cells are sensitive to agitation. (elephant ear, etc.)
The other factor that not been discussed here is, the gage pressure. You said your reactor is half empty. Does your mıcroorganısm (MO) affect by the O2? des ıts growth facultative? Or your product get affected by O2? if it is, you may empty the o2 in the tank or ıncrease your workıng volume. but thıs tıme the gas pressure wıll be dominant. So make sure you know your production conditions ın shake flasks well, to adapt to biioreactors.
PS: My paper on scale up of bıoethanol has just accepted and ready to be published, and when ıt ıs available you can read it for more ınformatıons and calculation strategies.
At the shake flask you probably have rather different agitation conditions, as compared with the considered bioreactor. The dissolved oxygen concentration and the pH are also likely not controlled at the shake flask, while at the bioreactor they are usually controlled variables. You may possibly find useful answers given to a somewhat related question: https://www.researchgate.net/post/How_can_I_control_Ph_in_the_bioreactor
- Badges
- Science topic
- Similar topics
- Engineering
- Chemical Engineering