What is an Autoinduction medium?

The principle of autoinduction media is based on carbon sources in the medium that are metabolized differentially to promote high density cell growth and automatically induce protein expression driven by lac promoters.

How does IPTG induction work?

IPTG or Isopropyl β-D-1-thiogalactopyranoside is a chemical reagent mimicking allolactose, which removes a repressor from the lac operon to induce gene expression. An allolactose is an isomer of lactose, formed when lactose enters cells. It acts as an inducer to initiate the transcription of genes in the lac operon.

How much do IPTG add for induction?

Thus, the trend is valid for a broad range of induction conditions. While the optimal inducer concentration is 0.1 mM IPTG at 28 °C, it decreases at 34 and 37 °C to 0.05 mM IPTG. A transition area is visible at 30 °C, where 0.05 mM IPTG is preferable for early induction and 0.1 mM IPTG is better for later induction.

How does IPTG affect cell growth?

IPTG concentration had a negative effect and could be ten-fold lower than the concentration commonly used in molecular biology (1 mM), while keeping expression at similar levels and inducing less damage to cell growth. The expression of LigB (131-645aa) was associated with cell growth.

What is the difference between lactose and IPTG?

IPTG is a structural mimic of lactose (it resembles the galactose sugar) that also binds to the lac repressor and induces a similar conformational change that greatly reduces its affinity for DNA. Unlike lactose, IPTG is not part of any metabolic pathways and so will not be broken down or used by the cell.

How much IPTG should I add?

A typical final concentration when using IPTG to induce protein expression under a lac operon is 0.1mM IPTG. For direct application to a solid media plate, add 56 μL of a 100mM IPTG stock solution directly to the plate top and allow to dry before inoculating plate.

How long should you induce with IPTG?

The optimal incubation temperature and time for induction will vary depending on the target protein. We recommend varying induction temperature and time to optimize expression (37°C for 2-4 hours, 30°C for 4-6 hours, 22-25°C for 6-16 hours and 12-15°C overnight using 0.4 mM IPTG).