Need some help on growing plasmodia and eliminating contamination

[Maxwell]

Hello. Recently I’ve been trying to grow some unidentifiable plasmodium on some water agar plates. I obtained this plasmodium by finding it under a decaying log on a hike. Since all plasmodia look similar, I wasn’t able to identify it without being able to see its fruiting body. You can see the original plasmodium I found in the second picture. Anyways, I’ve had some trouble with actually growing it. If you look really closely around the central agar cube in the first photo, you can see what looks like veins from the slime mold. My problem with this is that those veins aren’t actually the slime mold itself, but what I think is raised bumps in the agar from where the slime mold used to be. I know the slime mold is there as I’ve seen it under my microscope, but it hasn’t grown big enough to be visible with the naked eye. I’ve been feeding it oats, but it hasn’t grown big enough. I think the problem is that I just haven’t given it enough time to get bigger. However, the problem with just waiting is that within a couple days, every one of my subcultures just gets overrun by mold. I can’t just wait for it to grow because the mold always takes it over before it can get big enough. The mold always grows on top of the agar and not inside of it, so it isn’t getting contaminated while making the agar. The contamination is probably getting in while I take of the Petri dish lid off to look at it under the microscope. 

So, what I would like is just some tips on how to get the slime mold to grow faster, or how to reduce mold contamination on my plates.

Any reply is appreciated.

(Also, sorry about the first photo. I don’t know why it uploaded sideways.)

[Kenneth Ramos]

I too have problems with fungal hyphae.  It seems no sooner than I begin a new moist chamber the mold seems to be waiting.  The bumps or tracks that you see on the agar are just that, plasmodia for the most part do leave what I have often read referred to as "slime tracks." I oftentimes see them in my cultures too. As for growth of the plasmodia, only time and nourishment are your best resources in growth. So far one thing I have noted is that P. polycephalum grows in size or seems too, much faster than P. roseum which I am growing at present.  I have a subculture of P. roseum that appears to be taking its good sweet time in both eating and growing and seems to prefer hiding beneath the filter paper.  The original plasmodium that I obtained it from appeared right before I was getting ready to throw out a moist chamber culture well over a month old of dogwood tree bark and it has grown to well over 3 to 4 cm in about another month and seems to prefer the standard diet of oat flakes.  The subculture is a very picky eater.  I don't know if it might be the developing microbial flora that it is waiting on or something of the oat flakes themselves that it likes or doesn't like. All in all its kind of like taking care of a 5 yr. old.