If you want a more efficient, cheaper way to do bacterial transformation, if using a small DIY cannon to create a shockwave that forces bacteria to take up DNA from its surroundings sounds like your type of fun (if not, why not?!), you are definitely going to like this article.
In a study published in 2011, Dipshikha Chakravortty et al (Prakash et al., Anal Biochem., 419, 292-01) described a small, novel device for bacterial transformation. It was 30 centimeters long, a few centimeters across and consisted of a plastic tube lined with explosives (yes, explosives).
One end was wired with an electronically-controlled spark-plug detonator, and the other open end aimed at a reservoir containing a suspension of bacteria and DNA. In effect, this was a homemade, miniaturized cannon that created a controlled explosion to deliver a shockwave that propagates into the bacterial-DNA soup below. Nice.
How can this facilitate bacterial transformation?
The explosion creates a wave of hot gases that propagates through the cell-DNA suspension and creates microscopic bubbles that set off secondary shockwaves. The researchers believe that these shockwaves create momentary disturbances in the cell membrane that allow DNA to enter the cell and cause bacterial transformation.
But what prevents the cannon blast from just splashing the bacterial soup all over the lab? The trick is using a piece of foil over the cell suspension and positioning the barrel of the tube just the right distance away. Once the blast is generated, the foil transfers the right amount of energy into the liquid. The team demonstrated that brass and copper foils work equally well and the foil thickness between 100 and 180 mm gave comparable results. The number of blasts also did not matter as one blast was just as effective for bacterial transformation as three or five.
Yeah, yeah, but does it actually transform bacteria?
In the end, the micro-shockwave cannon generated 1.5×10-5 transformants per bacterium with E. coli using a single shot, whereas no bacterial transformation was observed without the blast.
The transformation rate was about the same as with electroporation (the bacterial transformation technique you are probably more used to, which zaps bacteria with electricity). However, unlike electroporation, which is damaging to the bacteria, using shockwaves leaves bacteria relatively happy and unharmed because the cell membrane disturbances are localized.
Also, the blasting technique is about 300 times less expensive and takes a third of the setup time compared to electroporation. So the next time you design bacterial transformation experiments, maybe you should consider treating the bugs to some inexpensive shockwave therapy!
For more tips, tricks, and hacks for getting your experiments done, check out the Bitesize Bio DIY in the Lab Hub.