Hey guys i was just looking for some insight as to why some choose heat shock vs electroporation. More so in terms of quality of cell transformation, rather than price, because currently my lab is using an electroporator but have had some mixed results and was considering trying heat shock as an alternative.
Heat shock vs eletroporation
Posted 06 September 2015 - 12:58 PM
Electroporation can give you much higher transformation rates, however, with good competent cells, I have found heat shock to be in the range of 10^8 - 10^9 cfu/ug DNA, which is about the same as typical electroporation rates. I have found that this varies with experience in preparing competent cells and the protocol used (I use the top10 one from openwetware.org on DH5a cells)
On the other hand, electroporation is supposed to be able to deliver 10-20 times the amount compared to heat shock, but in my hands never seems to do so.
Posted 06 September 2015 - 03:26 PM
To add to Bob's comments, chemically competent cells are also easier to make...requires less culture, and the cells only need a 1-2 washes whereas electrocomepetent cells require a greater volume of culture and 3-4 washes.
As bob said the main advantage to electrocompetent cells is that they are typically more efficient. The only time I've ever absolutely needed the enhanced efficiency was to transform three plasmids at once. Chemical cells are good enough for double transformations, but not triple in my hands.
And you said price was not an issue...but $$$ is always important. Electroporation cuvettes can be pricey (2-3$ each). Chemical transformations require nothing extra. For the occasional transformation it's a non-issue but our lab does thousands of transformations each year so it would add up.
Edited by labtastic, 06 September 2015 - 03:39 PM.
Posted 09 September 2015 - 03:45 PM
Thanks guys, yea we are just having some issues with cell expression in our lab and we only transform via electroporation and was considering using other protocols. My PI is very big into electroporation for only a single plasmid and she recently bought a new batch of cuvettes for the lab since we were having with transformations. I try a few transformations with either chemical or heat shock to see if maybe we have a better efficiency.
Posted 10 September 2015 - 11:49 AM
Concerning you expression issues...are you freezing your expressing strains?
Posted 12 September 2015 - 10:02 AM
No we only do a single use on each strain grown. We will freeze only our competent cells at the moment, expression hasnt been the biggest problem for our lab as of late!
Posted 14 September 2015 - 04:34 AM
Cool. Yeah I've run into too many issues getting strains to express again after being frozen. Fresh transformations every time really is worth it. Good luck.