The Effects of Different Mushroom Growing Methods on Mycelium Growth

Jenna Schneider

Scientific Research and Design

Omaira Pacheco

December 14, 2021

ABSTRACT

With increasing demand for resources, such as food, textiles, and land, it’s crucial that new and more sustainable solutions replace the current ones in place. This experiment tests the growth of mycelium from two different forms of the Ganoderma lucidum mushroom species: a liquid culture and spore powder. From these two methods, it was predicted that the liquid culture would produce more mycelium growth than the spore powder. This was tested by adding a sample of each form of G. lucidum mushroom to different agar plates that consisted of agar agar, light malt extract, and water. The experiment proved that the G. lucidum liquid culture grew more mycelium than the G. lucidum spore powder grew in the four day period. In a few samples of both the liquid culture and the spore powder unknown mold growth was observed.

INTRODUCTION

The inspiration behind the idea was concern for the environment, specifically the growing environmental impacts of the textile industry. At the rate the human population is growing, there won’t be enough animals to support society’s needs, especially considering the resources that go into raising each animal to the desired standard. Not only is it not sustainable, but it is also unethical. With this, research was conducted into different fabric alternatives that were more eco-friendly. Currently, there are companies that are working with discarded fruits, leaves, fungus, and other plant based products. For example, one company that stuck out was called Mylo. At Mylo they experiment with growing mycelium, a network of thin branches called hyphae that form mushrooms, and turning it into leather.^[1] As research showed limited details about the different processes behind making their leather, the purpose of this experiment was to recreate something similar to compare the resources that go into creating this new leather with the resources that go into creating the current animal leather we use now. To conduct this experiment, it was necessary to answer the initial question that arose in the first step of making the mushroom leather: what method is used to grow mushroom leather? To test this, the experiment compares the difference in mycelium growth between reishi mushrooms grown from a liquid culture to mycelium grown from actual spores. It was hypothesized that if reishi mushrooms are grown from a liquid culture, then they will grow larger mycelium in terms of surface area over a given amount of time than the mycelium grown from spore powder. However, if this was incorrect, then the null hypothesis is that the method in which the mycelium is grown has no effect on the surface area growth. The independent variable was the method in which the mycelium is grown and my dependent variable was the growth itself. Throughout the experiment, the environment, incubation time, amount of light, agar concentration, type of mushroom, and measurement of the samples were kept as constants to obtain more accurate data. Since this experiment involved the growing of fungus, which is not harmful and is often used medically, safety precautions were taken such as keeping the mycelium contained in petri dishes during the entire course of the experiment.^[2] To properly dispose of the bacterial agar plates, the bacteria in the petri dishes were sterilized in an autoclave then disposed of in the trash with the remaining liquid drained in a biohazardous liquid receptacle.^[3]

MATERIALS AND METHODS

This experiment is conducted to observe the difference in appearance and mycelium growth of two different forms of the Ganoderma lucidum mushroom species, including a liquid culture and spore powder. For this experiment, 10 agar plates were prepared using 5 g of agar agar powder, 5 g of light malt extract, 250 ml of water, and a media bottle. The agar agar powder and light malt extract were added together in a Erlenmeyer flask along with the water and it was brought to a boil. When all of the ingredients were mixed well, with the powders dissolved in the water, about 20 ml of agar was poured into each petri dish.^[4]

With the agar plates completed, the petri dishes were divided into two groups of five. The first group of five was administered 3 drops each of the G. lucidum liquid culture and the second group was given 0.05 g of G. lucidum mushroom spore powder. Then, each petri dish was labeled and stored in an incubator at 100°F. Observations in appearance and measurements of growth in surface area were recorded every day for four days with the experiment repeated two more times. Throughout the experiment, the environment, incubation time, amount of light, agar concentration, type of mushroom, and measurement of the samples were kept consistent to accurately observe the different growth patterns. Failure to keep these factors consistent could account for systematic uncertainties, so it was important to make sure all the equipment was sterilized and the procedure was followed exactly how it was described while conducting the experiment. In addition, it was essential to conduct this experiment multiple times to eliminate possible errors and outliers in the data.

While there can be dangers working with fungi, the G. lucidum species is safe and edible for humans.^[5] It has been used across many experiments and is non-harmful. While conducting the experiment, it was important to still maintain safety procedures, including sterilizing equipment, maintaining a clean environment, wearing goggles and gloves, and eliminating food and drink in the lab space. At the end of the experiment, the mycelium samples were sterilized in an autoclave and properly disposed of in the trash with the remaining liquid drained in a biohazardous liquid receptacle.^[6]

DISCUSSION

In collecting the data, the growth of each of the samples was sectioned in terms of shape to more accurately depict the differences in the growth shape between samples. Since each sectioned shape roughly took the form of an ellipse, the mycelium growth was calculated using the following equation for the area on an ellipse (A represents the ellipse area, r1 represents the horizontal radius of the ellipse, and r2 represents the vertical radius of the ellipse):

After calculating each surface area, it was recognized that the results supported the original hypothesis that reishi mushrooms grown from a liquid culture will grow larger mycelium in terms of surface area over a given amount of time than mycelium grown from spore powder. While the G. lucidum liquid culture presented substantial mycelium growth (Table 1), the G. lucidum spore powder only grew about half as much as the liquid culture (Table 2). The average mycelium surface area of the spore powder samples had a little fluctuation across all three trials, and the average mycelium surface area of the liquid culture samples showed minimal fluctuation across all three trials. After comparing the data, the alternative hypothesis that reishi mushrooms grown from spore powder will grow larger mycelium in terms of surface area over a given amount of time than mycelium grown from a liquid culture was rejected along with the null hypothesis that stated: the method in which the mycelium is grown has no effect on the surface area of growth.

Table 1 documents the average calculations of surface area taken from samples grown with a G. lucidum liquid culture over the course of four days. As represented in the data above, the liquid culture growth fluctuated but increasingly grew in each of the three separate trials.

Table 2 reveals the average calculations of surface area taken from samples grown with G. lucidum spore powder over the course of four days. As apparent in the data above, the spore powder was consistent in mycelium growth and increasingly grew in each of the three separate trials.

Graph 1. Average Surface Area of Mycelium Grown from a Liquid Culture vs. Average Surface Area of Mycelium Grown from Spore Powder

Graph 1 compares the averages of each of the three trial averages for both the G. lucidum liquid culture and the G. lucidum spore powder across four days. As depicted in the graph above, the G. lucidum liquid culture and the G. lucidum spore powder averages both had a positive trend of mycelium growth; however, the G. lucidum spore powder only grew about half as much as the G. lucidum liquid culture.

Table 3 showcases pictures of a growth of the G. lucidum liquid culture sample over the course of four days. As each day passes, there is consistently more mycelium growth scattered across the sample as well as condensation on the top of the petri dish.

Table 4 displays pictures of the growth of a G. lucidum spore powder sample over the course of four days. As each day passes, there is a small yet increasing amount of mycelium growth with condensation on the top of the petri dish.

In using mushrooms of the same species, the difference in growth was effectively compared as observed in Graph 1; however, a possible factor to consider as to why the spore powder didn’t produce as much mycelium growth could be due to inconsistencies in the powder itself. Another element that was not originally accounted for was the growth, while minimal, of other molds on the mycelium samples as shown in Table 3 and Table 4. This likely resulted because of the exposure of the sample to possible mold particles in the air.

CONCLUSION

By testing the difference in growth between the G. lucidum liquid culture and the G. lucidum spore powder, the alternative hypothesis was accepted because G. lucidum liquid culture grew a larger colony of mycelium in terms of surface area. The smaller surface area of mycelium growth in the spore powder samples could be accounted for by inconsistencies in the spore powder or lack of incubation time on the agar plates. In addition, as the experiment was only expected to grow mycelium, it also grew other unknown molds due to its exposure to mold particles in the air. For further research, one could use a sample of the pure mycelium grown in the G. lucidum liquid culture and inoculate new agar plates with the pure sample to observe the difference in mold growth between the G. lucidum liquid culture and the G. lucidum pure sample.

REFERENCES

Flinn Scientific, Inc. (2017). Safety Notes. Flinn Scientific. Retrieved December 2, 2021, from https://www.flinnsci.com/api/library/Download/d5e38df20edb46ba8e8b3ead11c545cf

Ganoderma lucidum (Lingzhi or Reishi): A Medicinal Mushroom. (2011). In Herbal Medicine: Biomolecular and Clinical Aspects (2nd ed., p. 500). CRC Press. https://www.ncbi.nlm.nih.gov/books/NBK92757/

Mylo Unleather. (n.d.). Sustainable Vegan Mycelium Leather. Mylo Unleather. Retrieved October 18, 2021, from https://www.mylo-unleather.com/

Urban Spore. (2018). How To Prepare Agar. Urban Spore. Retrieved November 10, 2021, from https://urbanspore.com.au/how-to-grow-mushrooms/how-to-prepare-agar/