Week 5: New Molds, Spore Prints, Mycelium Growth Update

Welcome to Week 5 of my Senior Project! 

After encountering some setbacks last week, this week was all about devising backup plans and embracing a trial-and-error approach! 

First, I experimented with making new silicone molds. I used wood slats to construct a grid-like structure that the liquid silicone would be poured into, taking extra care to seal the edges. After letting it set, I removed the silicone out of the container and carefully cut around some pieces to refine its shape. While silicone may not be the most environmentally friendly material, it does offer several advantages over traditional plastics. Unlike single-use plastics, silicone products can be used repeatedly. It’s also chemically inert, meaning it does not react with most substances or leach harmful chemicals into the environment. This makes it a safer option in comparison to some plastics, which may contain harmful additives like BPA (bisphenol-A). While silicone itself is not typically recyclable through conventional municipal recycling programs, there are specialized processes to recycle it. 

Along with new molds, I tried making new spore prints. Finding suitable mushrooms took me to various parts of New York! From my local grocery stores to Koreatown, Soho, and Red Hook, I went in search of the freshest oyster mushrooms that looked suitable for prints. At the supermarkets, I ended up picking out two different species of mushrooms: king oyster (Pleurotus eryngii) and pearl oyster (Pleurotus ostreatus) mushrooms. King oyster mushrooms are characterized by their thick, meaty stems and small caps, while pearl oyster mushrooms have more delicate, pale-colored caps with shorter stems.

With a couple successful prints, I was able to return to the lab! Using a Q-tip, and ensuring that both it and the agar plates were sterile to try to prevent contamination, I lightly touched the Q-tip with the spore print and gently placed it onto the surface of the agar plate. This allows the spores to germinate and grow into visible colonies. At the lab, I was able to check in on the plate with the shiitake mushrooms from a couple weeks ago (see Figure 1). As you can see from the picture, I suspect a certain mold, potentially the Penicillium species, is growing. Certain molds can produce green pigments as they grow on the agar plates. They are common contaminants in laboratory settings and can often be found in the air or on surfaces. I’m not sure if any mycelium is growing at all, but plan on giving it a couple more days. In some cases, mycelium can outcompete bacterial or fungal contaminants on agar plates, especially if the conditions favor the growth of the desired fungus. In a couple days, I’ll carefully examine the plate to identify if there are any areas where there is healthy mycelium that appears relatively free from contamination. If there is any, I’ll carefully cut out small pieces of agar containing the mycelium and transfer them to new plates. 

Since we’re about halfway through the project, this week I began developing some backup plans instead of using the spore prints in case of full contamination. Liquid mycelium cultures, also known as liquid inoculum or liquid spawn, are an option I’m looking at. More on this next week!

Figure 1.