Re: [DIYbio] Isothermal microcalorimetry for bacterial activity.

On 04/14/2015 03:03 PM, Simon Quellen Field wrote:
> Would be possible to use a NTC thermistor, and Arduino for data acquisition, for detecting temperature changes in a medium
> containing bacteria and nutrients in a DIY approach?
>
> Has anyone had any practical experience with this technique?

I've used thermistors. Not like you want to.

They vary from part to part a lot. The sensitivity might be OK. What strikes me
is your aim is to measure very dilute solutions and I wonder what "containing bacteria" means?


" heat dissipated by bacterial metabolic processes in an adiabatic environment measured with thermistors to estimate the organic
load in wastewater. Imagine keeping an aerated bioreactor containing bacteria fed by domestic effluents."

Are the bacteria fixed, or do they wash away? If they are fixed on a surface, there's a chance.

Insulation against heat flow is a very big thing in this setting because the thermal mass of the
whole experiment is huge compared to the bacteria mass in aggregate.

How do you reconcile adiabatic and aerated? How do you reconcile adiabatic and "fed by"?
Is the aeration all just recycled gas inside the reactor with no ins or outs of gases?
Do you seal up the system and watch its temperature and pressure change for a while -- that's
what we usually call adiabatic...

Here's an idea: Reduce the heat sink mass surrounding the supposedly fixed bacteria. Aeration can stir a vat of
solution, but for exposing it to the bacteria flow a small trickle of it over them in a thin sheet so
it does not carry away much heat. Measure differential temperature of the in and out drip of solution
flowing over the bacteria surface.

If the bacteria are not fixed, just washing around in solution, then the above is no help, and bioreactor
insulation is almost everything.

(You still need the nice stable temp sensor system to measure heat generation...)

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