I started my experiments based on the plan. Here are my first impressions.
How does it look?
The bacteria powder is very concentrated, so I had to adjust my dilutions and re-suspend the FDB vial in 10mL instead of 5mL. The dilution was fairly rapid and easy, although I did notice some clumps that took longer to dissolve.
I plated the 125mg/mL slurry as instructed in the LabTie protocol. The lawns actually looked pretty good (see figure 2). They were well homogenized and easily pipettable. I wrapped them in parafilm and stored at 4oC overnight. I am planning on plating synchronized L1s tomorrow.
Figure 2: (left) Comparing the appearance of the resuspended OP50. (right) appearance of the Freeze dried bacteria lawns on Day 1.
How does it work in microfluidic channels?
Not well. When trying to test the 50mg/mL freeze dried bacteria slurry, I had an unpleasant surprise. Although the resuspension seemed complete, it turned out to be a lot of small bacterial clumps that were hard to load in the ScreenChip.
I decided to try a lower concentration, following the Labtie protocol for liquid culture (2.5 mg/mL final). The good news is that the clumps were small enough to not irreparably clog the chip, but it was definitely suboptimal.
Figure 3: Rehydrated freeze dried OP50 clumps up creates fast clogging in microfluidic chip. Fresh OP50 was pelleted and a 10 mg pellet was resuspended in 1 mL.
I still need to gather another day worth of data but I am curious to see how freeze dried rehydrated OP50 compares with fresh bacteria food when it comes to feeding behavior.