Endy:Chemostat
This page is for storing information about operation of a bench-scale chemostat designed by Ben Kirkup. It is in development.
Also see STN Chemostat Design for an alternative, flexible chemostat design.
Design
This is one of the borosilicate chemostats produced before the switch to quartz. It does not have all the recent design improvements that Finkenbeiner now incorporates (offset air outputs; reinforcements on the struts).
This is an original AutoCAD output for a chemostat design. It is similar to the design originally employed and fabricated by D. Dykhuizen.
The basis of this chemostat is, as designed by Dykhuizen, a siphon which maintains a steady media level passively without need for a second media pump line (an evacuation pump). Mixing is also joined with aeration, as in Dykhuizen's original design. The design has been reinforced, scale changed, and limits on rates redesigned. Glass beads have been added above the air input to promote mixing physically. It is an ~60 ml chemostat as produced now (operating volume actually depends on air pressure and flow rate, at very high flow rates [10 mls/min or greater] or air pressures [which can compensate for the high flow rates]).
This chemostat is best fabricated with the headpiece made from quartz. If minimal media is being used, the body can be of borosilicate and this will protect the cells from 254nm UV, but the UV will penetrate into the head prevent any cells from growing up the feed line, even if they attempt to form a biofilm.
Setup
- Wash out chemostat. don't lose the little glass beads.
- autoclave making sure that all tubes are connected.
- setup everything and run media through the device for a little while. this is a good time to calculate the flow rate.
- drop some cells in the reactor and off you go.
Operation
Normal Operation
- Setting up the reactor for the run, avoiding contamination, etc.
Troubleshooting/Common problems
Bryan, anything here?
Temperature consistency in water bath
no problems here. keep the thermometer close to the reactor to make sure you are at 37C where you need to be. use the little surface water balls to prevent evaporation.
Masterflex tubing in the pump
avoid crushing this tubing by removing the clamp on the parastaltic pump when it is not running.
Contamination
so basically after about three days the run is going to become contaminated. You will know that this happens because the OD will go crazy and diverge from steady state. somehow cells are getting in the top feed line and begin growing before getting to the reactor. I haven't really been able to figure out what is the best way to prevent this, perhaps running the reactor with a higher flow rate or finding a way to keep bubbles from forming and making their way up towards the feed line. Using minimal media might be the way to go here since it's less viscous yet this will prevent you from running as fast.
