Talk:Chemostat

Against the grain

Sorry to have to ask but is it really true that bacteria can "travel upstream quite easily"? I don't know much about how most bacteria locomote but I've learned a bit about fluid dynamics and from that would guess that bacteria traveling upstream would be impossible. At length scales the size of bacteria, water is like molasses and trying to imagine swimming upstream in quickly flowing molasses is tough. 128.6.227.175 (talk) 16:05, 18 January 2008 (UTC)

Oh, just so people know, the concept being addressed here is the Reynolds number. It is used to quantify the experience of viscosity in fluids at different scales. Bckirkup (talk) 18:09, 4 February 2008 (UTC)

So, there are at least two questions in play here. First, sometimes chemostats are run at very low dilution rates. In this case, should the feed line be contaminated, chemotaxis and flagellar swimming are more than sufficient to allow progression into the media chamber.

Second, even with high rates of dilution, many bacteria can adhere to surfaces and can progress as a biofilm against the flow.

These factors make it very important to have all possible barriers between the growth chamber and the media reservoir. Some options include multipart media reservoirs such that none of them have all the required nutrients, an air gap with UV radiation between the media inflow and the growth vessel, a filter or some other physical barrier. Bckirkup (talk) 16:24, 18 January 2008 (UTC)

Contamination of the reactor through the effluent tube can also happen during mistakes in removing volume (for sampling) and creating negative pressure in the reactor. Qchristensen (talk) 14:45, 25 June 2015 (UTC)

Oh and to state the obvious if the worst happens (bacteria get into the media reservoir). Take the chemostat down and start over. 140.203.12.240 (talk) 15:40, 24 January 2008 (UTC)

There are a number of reasons that this is not a suitable solution. First, media reservoirs may be large and the media expensive. Time may be important and chemostat experiments can take many months. Cryptic contamination will change the inflow media composition - and cryptic contamination up the line changes the effective volume of the chemostat. Basically, contamination of the feed line and then the media reservoir is a critical failure in the operation of the chemostat, and while restarting is in fact the only solution to the problem, it is critical to avoid this situation in the first place. Bckirkup (talk) 18:09, 4 February 2008 (UTC)

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