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Help Culturing Physarum Polycephalum Directly onto 3D Printed Surfaces

I am currently attempting to culture physarum polycephalum directly onto 3D printed surfaces without the application of agar. I have had luck previously creating cultures on agar coated surfaces, but I can achieve a higher resolution without the coat and have spoken with researchers who have claimed to accomplish this.

Environment: enclosure is kept at 70% humidity, 72 degrees, and contains a HEPA air filter for circulation and decontamination. Light is low, it's in a basement and the enclosure is walled off.

Growth surfaces: 4"x4" tiles 3D printed on a Formlabs Form 2 with white resin, decontaminated according to biocompatibility protocols used for bacterial growth (two cycles in 90% isopropyl alcohol, full drying, UV curing). The surfaces are sterilized with 70% enthanol and allowed to dry before colonized oats are added onto the surface with sterilized tweezers.

Biology: Species is physarum polycephalum, food targets are unclaved raw oats. I maintain a mother culture on an agar surface and have had luck transferring to other agar plates as well as paper towels, but not to plastic.

Blooming: The HEPA filter puts off a faint blue light. I have largely obscured it, but one of the cultures I was growing on paper towels began to bud after two days. I have heard that this happens in response to UV light exposure. Any advice on preventing this behavior would also be appreciated.

I was advised to leave a layer of water below the printed surfaces to improve the humidity levels in my enclosure. I seeded new growth today and am hoping this helps.

Additionally, if anybody has experience taking photos of physarum growth over time, I would appreciate the help.

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Comment by Sarah Vitak on December 2, 2020 at 17:16
curious how this went? and what exactly you were aiming to do?
Comment by ian on March 30, 2018 at 20:39

I apply dry rolled oats  straight out of the bag (not even organic) and add water,  on a flake by flake basis a couple of drops per oat.  In  bulk  I don't normally bother weighing anything,  I've been applying oats by the handful -  literally; watering with a houseplant watering can ( Big Bang Fair) but it's around 1:2 oats to water. 

Physarum feeds off bacteria and fungi  it's amazingly containment tolerant - it will grow around mucor and aspergillus and simply move away from invaders it doesn't like. If you need something 'slow release' microwave a 1:3 oats to water mix until it steams,  roll out and and add slime - it's good for around seven days. 

Comment by Nicolas on March 30, 2018 at 18:18

Thank you so much! It seems like I wasn't seeding enough onto the print. I will try with more colonized oats tonight and see if that helps. It's good to know that I don't need the HEPA filter in there as well. Do you boil your oats or use dry food?

Comment by ian on March 30, 2018 at 10:04


There's no need for sterility with physarum - the hepa and substrate sterilisation are unnecessary.  I've used pla printed mazes before,  slime will crawl on it but seems to quickly abandon it when something with a bit of moisture is available.  A textured surface on the print might work better as it'll hold a film of water.  To transfer it just apply a decent sized blob of colonised oats - a teaspoon to a tablespoon full,  that way you have a good load of biomass ob your model. 

The only way to avoid sporulation is to exclude light - no way around that one but filming them is simple - just use a flash,  it's not on long enough to trigger spores.  A shot every five or ten minutes is ideal and I've filmed for weeks like that 

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