SortoStat/Operation

Materials

• Microfluidic chemostat chip
• Lysis Buffer
  • prepare lysis buffer by adding 10mg/ml Lysozyme to Pierce B-per Reagent.
• Media (+ antibiotic if necessary)

Setup the device

Prime the control channels

1. Ensure that the valve leading to the 3-way split is in the off position so that no pressure is getting to microfluidic tubes.
2. Disconnect the large tube leading from the top pressure nozzle to the media/lysis buffer jars, cover with parafilm, and turn the valve counter-clockwise until it stops. (OFF position)
3. Load the tubes leading to the control channels with sterile h20
   • Seem to always get some growth in the control channel anyway, don't suspect that it seriously affects valve performance.
   • If you have recently run the chip many of the control tubes will already be full (not sure how they leak, but they do), so to save time you can pressurize the control tubes and then visually inspect the chip to see which control valves are not filled with water. Then can selectively fill those rather than doing all 32.
   • May also consider just leaving pressure on the control lines if you have <2-3 days between experiments, the loss of gas will be worth your time.
4. Place the chip on the stage and turn the valve before the 3-way split to the ON position.
   • BE SURE that the regulator leading to the media/lysis jars is off and disconnected, otherwise you are going to start spraying media around.
5. Close all the valves and leave the chip for ~15 minutes to ensure that all the control channels have filled with water.
6. Visually confirm that the control channels are filled with water and open and close each channel individually to confirm function.
   • (may want to make this a feature in labview, so you can just watch while it opens and closes everything)

Prime the media and lysis channels

1. Insert tubes into the lysis buffer and media bottles and then insert the pin into the appropriate inlet channels
   • Lysis buffer is typically placed in the left input channel
   • Be sure to define the media inlet in Labview
2. Insert the 2 waste tubes (center and lower) and place the ends in the microfluidic waste jar.
3. Hook up the large tubes to the media and lysis jars and then turn on the pressure. Open appropriate valves to create a clear path between the inlet and the outlet in order to prime the media and lysis tubes. (should take about 1 min to prime the tube).
4. Clean out the chemostat with lysis buffer and then media. (particularly if re-using the chip)

Load the cells into the chemostat

1. Need to write a button into labview to open the appropriate channels automatically
2. Spin down cells at 2000rpm for 2 minutes and then suck up some of the suppernatant by attaching a small tube with a pin to a syrinnge.
   • This helps reduce the likelihood that a large piece of debris clogs one of the channels.

Operate the device

1. Prepare lysis buffer by adding 10mg/ml Lysozyme to Pierce B-per Reagent.
2. Spin down an overnight culture of cells at 2000rpm for 2 minutes to bring down large clumps of debris. The cells in the supernatant (which should still be cloudy) will serve as the cells to innoculate the device.

Operating Parameters

These will vary somewhat by chip, however have had success with

• fluid: 4.5psi
• push-down: 15psi
• push-up: 16psi

Notes

Jen & Caitlin have been running their chemostat at a dilution rate of .75 and reaching ODs of 1-1.6. This would be roughly 10K cells in the chip, i think. Haven't actually gotten a steady-state counted yet to measure what we are actually seeing.