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 $500 per month.
There are a few other options:
- There are models that are half the size. For us that’sbetter, but it’s still costly, noisy, heavy and big.
- There are -40°C freezers. They consume less electricity, and they’re a nice improvement over -20°C for storing samples. Some DIYbio spaces, like Counter Culture labs in Oakland, have opted for this solution.
- Another possibility is to use liquid Nitrogen. The temperature of liquid nitrogen is -196°C! It can be kept in liquid phase for a long time inside containers like this:
The problem here is that you need to constantly refill the tank. Liquid nitrogen is cheap, around 1$/L. But logistically speaking, it’s a challenge. You need to approximately refill with 30 Liters every month, which requires either to transport liquid nitrogen on a regular basis (not ideal, training and caution is required to safely handle liquid Nitrogen) or to use the service from companies such as Airgas and get a big cylinder stock. The company replaces when it’s empty. Then, once again, the problem becomes space, because these cylinders are big too.
One more inconvenience of liquid Nitrogen is that every member needs proper training to handle it, and the more it is used to take samples in and out, the more the liquid Nitrogen evaporates quickly.
Up until a few days ago, we thought that these were the only options. And then we fell upon this beauty:
The Shuttle™ Model ULT-25NE from Stirling Ultracold.
This is the -80°C freezer of our dreams! It's even portable! It's the perfect size to fit anywhere in our lab and it consumes only a fraction of what the big ones do. Its capacity is much smaller compared to typical models, but it fits 18 boxes of 2’', which is plenty for our needs. We could store all the competent cells and glycerol stocks we want with this system.
Let’s start the fundraising to get this new toy 😃
If YOU, the reader, would like to help us get the freezer of our dreams, you CAN do it here!
The Boslab team