The - 80°C freezer of our dreams ❤
We recently found the freezer of our dreams. Perfect for our needs!
But first, some background.
Storing cells is a major obstacle for DIYbio spaces. In any institutional lab setup, biological samples (an E. coli glycerol stock for example) are stored at -80°C, because at this temperature they last much longer than conventional freezers. At regular freezer temperature (-20°C) molecules can still jiggle a little and the sample gets damaged over time. We currently only have a regular 'kitchen' -20°C freezer, which means that the stocks for all the strains we obtain or engineer have to be renewed after a few months, by growing a fresh culture and cryo-preserving it again.
Competent cells are even more problematic. Cells are called competent when they received a particular treatment that makes it easier to introduce DNA into them, a process known as transformation. Competent cells are essential to any genetic engineering project. If you want to play with the genetic program of a microbe, at some point you have to insert DNA into it. The protocol to make cells competent is time consuming (take our intro lab class to discover about it!!!) and usually it is done once for a large amount of cells, which are aliquoted and frozen into dozens of tubes.
Once these competent cells are made, only one tube per transformation experiment needs to be used, so it's not required to repeat the whole preparation protocol. Competent cells are by nature fragile, because the treatment relies specifically on making their membranes more permeable to insert DNA. At -80°C, competent cells can last up to a few years, whereas at -20°C... only a few months.
We have successfully usedchemical competence and electroporation techniques to transform cells in our lab, but the competent cells we generate for both techniques are good for only a month or 2 if stored in the -20°C.. At BosLab, our members use competent cells for their projects and we also use these cells very frequently for our lab classes. We also need to store unique strains of non-pathogenic yeast and E. Coli in the lab and having to renew them every month is an inconvenience.
Now, when it comes to a -80°C freezer, there is little choice on the market. It's easy to find second-hand ones, but they look like this:
They weigh around 900 pounds. We would need to rent a fork-lift to bring it to our space, not to mention that our lab is on the second floor of an old building, and the floor would probably collapse under this monster. Moreover, we have a small lab space! We would not have any room for it. And they are extremely noisy, which is why they are usually kept in a separate room at most labs. Finally, perhaps the biggest limitation is that these guys consume A LOT of electricity, as you can imagine. We calculated that the electricity bill would raise by $500 per month.
There are a few other options:
- There are models that are half the size. For us that’sbetter, but it’s still costly, noisy, heavy and big.