Isopropyl-beta-D-galactopyranoside (IPTG) is often advertised as being free of dioxane. How important is this? I understand that some strains of bacteria are inhibited by dioxane, but how severe is this problem?

It is hard to say, as cheaper batches may contain quite a varying degree of dioxane. It also depends on what you want to do. For standard induction assays to screen blue-white screening in E. coli (for example), it tends not to be a huge issue. It is rare that a batch contains enough (after the usual dilution) to kill them off completely.

 

However, if you want to use IPTG to induce something and then do some molecular analyses on the same strain (e.g. transcriptome or proteome analyses) the varying amount of dioxane can skew the results significantly. There may also be mutants or specific species that are more susceptible, but I do not have data on that.

Thank you. We use it to induce protein overproduction and purify the protein.

For that it should be fairly robust, provided the overexpressed protein is not stressing the cells too much. If it does, it may render them more susceptible to dioxane exposure.