Pump setup using 8 + 8 vials

Hardware Peristaltic Pumps
1

Dear eVOLVER community,

Is the setup as shown in the picture possible? Can you separately control half of 1 pump rack and use one half for influx and the other for efflux? Or should I use all three pump racks and only use 8 pumps per rack?

eVOLVER setup
eVOLVER setup1280×720 309 KB

2

It is possible to use half of a pump rack only or to assign any given pump to a different task. You can see here in the turbidostat code that the first 16 pumps are assigned to influx and here that the next 16 are assigned to efflux. If you were to change the physical layout of where you connect the tubing, you would just need to change which pumps are used for which function in the code. You could do this on a pump by pump basis using a dictionary. This is done a bit differently in the chemostat code here and here.

However, I have a few questions about the fluidics scheme you’ve shown.

  1. Are you using chemostats vial to vial?
  2. How will you regulate volume within the vials? eVOLVER currently makes sure there are not overflows by removing any liquid above a certain level by excess efflux pumping (see the turbidostat links).
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3

Thanks for the response, Nate!

  1. It would be from turbidostat (0-7) to lagoon (8-15)
  2. I suppose I would need 2 efflux lines from the turbidostats then? One efflux to regulate the turbidostat, and one for feeding the lagoon? I made 16 of these 5-port vials according to the protocol on the Wiki: https://khalil-lab.gitbook.io/evolver/hardware/vial-caps/5-and-7-port-nylon-tubing-caps-construction-protocol. I have the emergency efflux too and would not need the bubbler line initially I guess.

Are there any recommendations somewhere regarding volumes of turbidostat/lagoons and flow rates for each pump in such a setup?

4

Are you running ePACE?

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5

Not exactly, we would evolve the phages themselves against specific bacteria.
So the flow rate in the lagoon needs to be fine-tuned so that only fit phages can infect while others are diluted out.

6

This seems very similar to ePACE to me in terms of eVOLVER usage. In ePACE, you also tune the host cell flow rates into a lagoon throughout the experiment to control selection pressures.

I’m going to recommend that you modify or wholly use the code for ePACE (download here). You can find out more about ePACE here. Read the note here about " Implementing Controlled Host Cell Density in Reservoirs".

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