Physarum always dies

[Miguel Grande]

Hello everyone,

I recently bought Physarum polycephalum from Carolina and I’ve been trying to grow it from sclerotia into plasmodium. I’ve attempted this several times. Usually it wakes up and looks healthy (bright yellow the next day), but then it suddenly stops growing or dies.

At first, I suspected contamination. My early attempts were done in a hood but without sterilizing the oats or the water. In those cases, the Physarum initially grew well but then dried out or decomposed after a few days.

To improve my results, I started autoclaving both the water and the oat flakes before adding them to new plates. However, after switching to sterilized conditions, the Physarum still either fails to become bright yellow or it dies after a few days—this time without obvious contamination.

Here is what I observed:

• First picture: Physarum one day after rehydration (non-autoclaved conditions, but done in a hood). Grown in the dark. Looks healthy and bright.

• Second picture: Same Physarum four days later. It dried out and died (also non-autoclaved).

• Third picture: After switching to autoclaved oats and autoclaved water, this is what I obtained after 3 days from sclerotia. The culture never became bright or vigorous.

My hypothesis was that the early deaths were caused by microbial competition. But now, after fully sterilizing everything, I’m confused because the result is still poor.

I followed the same procedures I would normally use for mammalian cell culture, so I am wondering if that could actually be part of the problem. Perhaps Physarum has different requirements, or maybe autoclaving the oats/water changes something important?

Has anyone experienced similar issues or has suggestions about what might be going wrong?

Thanks in advance!

[qiuwenxing]

I support the view of bacterial contamination because sterile culture under home conditions is impossible, and slime molds themselves also carry symbiotic bacteria. I suggest using better agar or switching to agarose (note not to introduce nutrients). Antibacterial agents (such as the triple antibiotic: Penicillin-Streptomycin-Amphotericin B Solution) are also an option (also, your agar seems a bit thin).

[qiuwenxing]

you can also keep it on the paper.