hello, I want to harvest Chlamydomonas sp without killing it is it possible?
can you link some articles?
I searched google but there are a lot of results and I am sure with one will keep the cells alive after the harvesting and it should be a cheap solution I hope you can help :)
Moderate speed centrifugation. 4500 rpm / 10 min. If you have a lot to harvest you will need a large centrifuge that can spin a big enough rotor to accommodate 0.5 - 1 L bottles. Cells will be viable and can be resuspended in different buffers as desired.
If you have large volumes, you can also add a sedimentation step. Although Chlamydomonas is motile, it will have a tendency to sink down, when you put it e.g. in a 2L measurement cylinder. Then you can decant the top e.g. 1.5L and reduce the work for centrifugation quite a bit.
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Yes, moderate speed centrifugation is OK. If you have large volumes to process you will need using continuous flow centrifugation. You can achieve similar physical forces than in batch processing and collect algae biomass at different concentrations (even as a paste, if you wish). Please see the link below for an example of this kind of centrifuge
https://algaecentrifuge.com/pages/algae-centrifuges#
Hello Furkan Güzel .
Centrifugation is a good option for your needs, but even at mild/moderate speeds you might still have problems regarding cell survival and viability, even considering that cells of these organisms are quite resistant to mechanical and chemical degradation. Within centrifugation techniques, I believe that the continuous flow centrifugation suggested by Jose Pedro Canavate probably is the most suited for you.
However, if your goal is to keep cells alive and continue to work with them afterwards, I would suggest you to try tangential flow filtration (or cross-flow filtration), as you can have great control of the pressure used in the filtration and minimize cell damage, it is easy to scale up and relatively easier than centrifuges to work in sterile conditions.
I didn't mention TFF since a larger scale unit isn't something a lot of Chlamy labs have. They will work to concentrate cells but will take a while. We never used them for viable cells at Rincon, our objective was primary recovery out of 100L culture vessels prior to microfluidization and downstream purification of recombinant protein.
Peter B Heifetz Yes, TFF has a few drawbacks. It takes longer to concentrate the cells than in a centrifuge and the cleaning of the filtration cartridges, done before sterilization, is also a little time consuming. The control over the filtration pressure and the easy sterilization procedure are good pros for this technique, though.
In any case, it is another nice option and in the end, the choice of which harvesting strategy is more suitable depends on the desired downstream biomass use, and time and resources constraints.
I used TFF many years ago and I learnt that this cell concentration process is much more species-specific than continuous centrifugation. As an example, fragile cells (Dunaliella, Isochrysis) suffered cell lysis as TFF increased microalgae density. Shear forces are a problem with this kind of cells. Of course, you need a pump (i.e. peristaltic) that minimizes cell damage. You do nit have any cell viability problem with species such as Nannochloropsis that have a strong cell cover. This variable response depending on cell type does not occur with centrifugation.
Hello, Furkan Güzel
The best and cheapest way is sedimentation. You can keep them somewhere to sediment in 1-2 hours (depending on your strain); However keeping it overnight can help you remove the extra water (based on my experience, I've transferred a 1.5 L broth to 200 ml without any difficulty). By doing this, I was able to reduce the volume by ~80% and therefore centrifuged them in the only available centrifuge in our lab (which had the capacity of 4*50 ml falcon).
I hope this was helpful to you.
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