How to shut off background lac promoter expression in LB
Here’s a tip that you may find useful if you are expressing proteins in E.coli using a lac promoter-based expression system, e.g. pET, in LB medium (L-broth).
Lac expression systems are typically induced in the lab using IPTG (isopropyl-beta-D-thiogalacto- pyranoside), which is a non- hydrolysable analogue of lactose, the natural inducer of the lac operon.
Tight control of expression from the lac promoter, which is required if the protein being expressed is toxic to the E.coli host or for a variety of other reasons, is not possible when using LB because it contains lactose.
But how does lactose get into LB? Read more »
Today I was browsing through the “new technologies” section on the Biocompare website. Apart from the amazing but super-expensive automation equipment that most of us unfortunately have little chance of getting our hands on (at least at the moment), five products caught my eye as being useful for improving techniques widely used by researchers. I hope you find some, or all, of them of interest to you…
For routine procedures involving cell lysis, it’s good for the lysis to be… routine. Of course there are many good and freely available lysis buffer recipes but for convenience and reproducibility you can’t beat pre-made lysis buffers.








