I grew C.butyricum in flask RCM medium, and it grew up to OD620=2 in 24h.
I transferred 100ml culture into 2L glycerol medium containing no yeast extract (start OD=0.2 after innoculation), and it can grow up to OD620=0.7.
However, the problem is that glycerol concentration was not decreased at all for several days (pH6.5, 37C, 250rpm).
I guess they grew using RCM medium (100ml) and dont use glycerol.
According to several papers, they can consume glycerol rapidly.
What do you think about this problem? and what can I do?
Dear Sangwoo Kim,
Is it possible to grow C.butyricum up to the OD of 3.5-4.5. Then add it into a medium that is limited carbon source with glycerol as the carbon source, instead of glycerol as the sole carbon source. From there maybe we can observe the consumption of carbon source which is glycerol. Just an opinion. Good luck!
Dear Hanisah,
Thank you for your answer. C.butyricum can grow up to the OD of 2 in my flask experiment. Have you ever experienced cell growth of C.butyricum up to the OD of 3.5~4.5? If you have, I will grow the cell more up to the OD you mentioned.
It seems, that some C. butyricum strains need biotin to convert glycerol efficiently, but low levels of about 4 µg/L will be sufficient. You might add this one to your formulation, if not already present. A suitable medium, described previsouly contains in grams per litre:
20 glycerol
0.5, K2HPO4.3H20;
0.5, KH2PO4;
0.2, MgSO4.7H20;
2.5 NH4CI;
0.01, COC12.6H20;
0.028, FeSO4.7H20;
0.035, Na2S/O4;
4"10 -6 biotin
You might also add 2 g/l CaCO3, to control pH.
Thank you so much for your comments. The suggested medium composition is similar with mine except Na2SO4. I didn't add Na2SO4. Do you think I'd better to add it?
And may I ask one more thing? I wanna know how much OD is expected during fermentation. So far I could grow C.butyricum up to OD620=2.
I appreciate you again.
This is difficult to predict, the OD value depends on the morphology of your organism, the wavelength used for measurement, the cell concentration an other factors. As your strain ferments, it likely makes only low biomass amounts, but rather forms acids as fermentation products, so OD could be low, despite glycerol is completely gone. you might check the pH, as medium acidification could also lead to incomplete growth and the phosphate buffer does not efficiently buffer below pH 6 anymore. check, if glycerol is left so see, if grwoth was complete.
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