Previously while doing induction, I use to get a layer of froth. but now froth is totally absent and even the colour of LB after induction s not the same. I changed LB, IPTG,antibiotics everything but still getting the same result. Once I purified protein from the same culture with less foam and my protein was inactive. what could be the reason? and does less foam formation affects the activity of protein? if not can I continue further with the culture?
Thank you in advance.
I guess you are using the exact same conditions, flasks and the same volume of culture in this failed experiments vs the previous ones. If you are scaling up your process and now is failing then you will have to do a bit more of troubleshooting.
Are you using a BL21 strain for protein production? I always transform the BL21 fresh for protein production experiments. Using old cells that have been on a plate for weeks or starting from a glycerol stocks can give you problems, I am not sure about the reason but I guess it is because of mutations in the plasmid or something related to that.
What is your enzymatic activity? Why do think it has to do with foam? I get foam in my cultures when the agitation is strong and also it can be due to cell lysis during growth.
Thank you Xi Jiang for the response.
Yes, I am using all the same conditions as before.
I am using BL21 strains. For every protein production I will stream fresh from Glycerol stocks store in -20. even I made one fresh glycerol stock as well but again from the previous one. About the mutation thing I don't know, but I will try to transform new bl21.
my protein is a DNA binding protein. I am not correlating foaming with the activity its just that its the only change I am noticing in my purification procedure and from there only I am not getting active protein.
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