You can prepare a stock solution of 0.5M IPTG and use 1ul for each ml. Meaning if your sample is 100 ml, you can use 100 ul from your stock. Usually works just fine and protein production is great.

PS: if you won't be using all of your stock solution, it's best to keep it in -20 refrigerator. I'd also recommend to prepare your stock in small volumes (0.5ml or 1ml) if you don't need a lot of IPTG or you wont be using large volumes.

As such, 1mM final concentration of IPTG is in general considered as "standard" for protein induction. To my experience, however, 1mM generally leads to a lot of inclusion bodies. With lower concentrations, the lower expression level gives more time for protein to fold in the cell and ultimately, the yield is better.

I would simply suggest that you check the expression level when using different IPTG concentrations.

Hi there,

0.01 to 0.5mM is the range of IPTG concentration to explore. Can't tell about the volume to add as it depends on the stock you have.

The final concentration may start at 50 micromol/L to 1.0 millimol/L in the broth tube. If you are using 37 deg temp for culturing BL21(DE3), use lower concentration of IPTG, while at lower temperature like 16 deg in case you want to improve solubility of the expressed protein, you need to induce at higher IPTG concentration. But remember that you need optimization of temperature and IPTG concentration for getting your protein in soluble fraction. One can use lactose as well at 1-5 mM final concentration. Also do not allow the cells to grow beyond an OD of 0.5 when you induce.

Usually we use 0.5mM IPTG in BL21strain, when the OD(600) of the bacterial fluid is between 0.6-0.8. And the protein product is well obtained. Just for your reference.

You can prepare a stock solution of 0.5M IPTG and use 1ul for each ml. Meaning if your sample is 100 ml, you can use 100 ul from your stock. Usually works just fine and protein production is great.

PS: if you won't be using all of your stock solution, it's best to keep it in -20 refrigerator. I'd also recommend to prepare your stock in small volumes (0.5ml or 1ml) if you don't need a lot of IPTG or you wont be using large volumes.

Thanks all of you for your kind response.

Hi Abdul,

I would recommend to test the final IPTG concentration in the range from 0.2 to 1mM. From my experience, 1mM IPTG resulted in the accumulation of the recombinant protein in inclusion bodies when the bacteria were cultured at 37°C for the whole time (overnight). I use 0.5 mM IPTG mostly, add it when OD(600) is 0.4-0.8 (depending on my target protein) and in most cases I continue further culture at 37°C only for 3 hours, after that cool the culture (by putting a flask on ice or cooling in cold water), and proceed with the culture at 16-22°C (depending on my target protein) overnight (no longer than 18h). Or lower the temperature immediately after IPTG addition to the pre-cooled culture. It worked very nice withmy proteins, e.g. human enzyme. In my case, lowering the temperature was crucial. I hope you will find my advices helpful and you will obtain successful results. Good luck! Cheers.

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