Science Buddies: "Ask an Expert"

For my science fair I made a 7 cm by 12 cm map with obstacles like mountains, different pathways through a forest, some buildings in the way, and hills for my slime mold, Physarum Polycephalum, to navigate through. I covered the maps (I have three which I will have going at the same time) with three layers of agar. I wetted some sterile oats and then used a swab to take a sample of the mold and put it on the oats (which are on the start point of the map). After that I put them in sealed tupperwear containers to trap moisture and left them overnight in a dark cabinet that was around 25 degrees celcius (that is the temperature it is supposed to grow in). It was to (no moisture) dry and didn't grow. So I repeated the experiment, but this time I put three cups of hot water below the maps (with towels in the water, so the maps wouldn't float around or tip). That was supposed to help create more moisture. I left it overnight again and it still hasn't grown at all (my kit says it should start growing visibly after a few hours). Why isn't it growing? How can I make it grow? Am I doing something wrong or incorrectly? Any help is appreciated.

Hi Emmy Barr and welcome to science buddies!
This sounds like a fascinating experiment and you have done a very good job of summarizing your work. I understand how frustrated you must be. I'm not familiar with your test kit but here are some possible areas of your experiment that you might double check versus the instructions:

(1) type of material used for construction of your obstacles. Maybe your choice of materials are sucking the moisture out of the agar?
(2) do the instructions tell you what type of agar to use and how to prepare it? And, are 3 layers specified?
(3) do the instructions tell you how much oats to use, and the type?
(4) does the type of mold match the instructions?
(5) and how much mold?

If none of these areas seem to be a problem, maybe tell us the name of the kit so we can find the instructions and maybe be more helpful!

The map is made of Styrofoam but it is covered by a clear paint so the moisture isn't sucked from the agar. The test kit is from boreal.org (if you search Physarum study and culture kit it should pop up). The kit came with agar called "corn meal, nutrient agar" and I am using that. It came with a plate of actively growing plasmodia and I have been using that, but I think I might not be using enough of it. The instructions say to use a dime sized piece and I couldn't acquire that much from the plate. I tried growing the mold from the scelortial stage but it just molded (that's why I am using the already growing stuff). I don't remember the instructions saying anything about three layers but in my first attempt I only put one and it seemed to not be enough so that's why I put three. The kit came with sterilized oats and I used those because the instructions said to use them, I also used a couple for each map because that's what it said. Like I said before I used to mold that came with the kit so I am relatively sure that is what is needed. I am beginning to think that maybe I wasn't using enough mold but I tried growing it from the scelortial stage and like I said it didn't work (it would also start growing mold, and not the mold I want). Any tips on how to grow it from the scelortial stage successfully? Any help is appreciated.

Hi Emmy Barr,

It sounds like you are carefully following the instructions that came with your kit. I will try to recruit other experts to review your question. In the meantime, I did find two Science Buddies projects which seem similar. Maybe if you review the procedure sections for those projects, you will get some ideas for how to revise your own procedures.

https://www.sciencebuddies.org/science- ... #procedure

https://www.sciencebuddies.org/science- ... #procedure

Let us know if either of these help. And hopefully other experts here at Science Buddies will chime in!

Thank you for all the help!

Hi Emmybarr678,

This is an excellent project, however, you need a viable slime mold culture to do the project. Slime mold will grow well on moist oatmeal in the dark and it is helpful to have an actively growing culture before you transfer to the maze. It sounds like, for some reason, that your culture was not viable.

What was the condition of your culture that you transferred? Had you observed any active growth prior to the transfer? How long did you have the culture between arrival and transfer to the maze? The humid atmosphere that you created should have allowed growth if the culture was still viable.

If you have time, I recommend that you contact the slime mold supplier and request a replacement culture as soon as possible. You should explain that your culture was not viable and request a replacement at no charge. . As soon as you receive it, transfer the culture to new oatmeal to ensure that the organism can continue to grow actively. You should be able to see visible growth within a day at ambient temperature.

If you don't have time before your science fair project is due, you will have to complete the write-up for your project with no results. Your discussion will include all the possible reasons that your culture did not grow, You will write up a complete display board and include all of the required sections as described in the project guide:

https://www.sciencebuddies.org/science- ... oard.shtml

Good luck. I hope you have time to get a replacement culture. Let us know if you need more help.

Donna