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Mushroom Cultures Stage: Mycelium, Spores, Agar and More

Working with mushroom cultures is a pivotal stage in the mushroom cultivation cycle. This phase serves as the foundational layer for the entire growth process, ensuring the propagation of healthy, viable mycelium that will eventually give rise to mature mushrooms. Getting it right is critical for both yield and quality.

Consider the culture stage as the birth and early childhood of the mushroom. At this vulnerable stage, they need extra care and protection from the various environmental threats that could hinder their growth. The spawn run represents their teenage years, a period of rapid growth and development, and the fruiting stage is akin to the mushrooms becoming independent adults, ready to face the world and propagate their species.

In this guide, you will learn about the various aspects of mushroom cultures, including understanding spores, working with agar and liquid cultures, how to avoid contamination, and more. This comprehensive resource aims to equip you with the necessary knowledge and skills to master this critical phase of mushroom cultivation.

Contamination

Contamination is a make-or-break issue in the culture stage of mushroom cultivation. At this early phase, the mycelium is highly susceptible to foreign microbes, molds, and bacteria that can quickly outcompete and overrun your cultures. Even a minor slip in sterility can result in contamination that ruins the entire project, wasting both time and resources.

Sterilization and Sanitization Protocols

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Understanding Spores in Mushroom Cultivation

Spores are the microscopic "seeds" produced by mature mushrooms, serving as the starting point for new fungal growth. They are typically collected in what's known as a spore print—a gathering of spores that fall from the mushroom's cap during its reproductive phase. These spore prints are your gateway into the world of mushroom cultivation.

If you're embarking on the journey of mushroom cultivation, getting to grips with spore prints and spore syringes is an essential first step. Understanding how to properly collect, store, and utilize these spores in a nutrient-rich environment is pivotal. It sets the stage for successful mycelial growth and, eventually, bountiful mushroom harvests.

Working with Agar

Agar is a gelatinous substance used as a growth medium for culturing mycelium—the vegetative part of fungi. It serves as a stable environment that mimics natural conditions, allowing mycelium to grow and multiply. The agar medium is crucial because it lets you observe the growth patterns and health of the mycelium, making it easier to identify and isolate robust strains for cultivation.

For those entering the world of mushroom cultivation, mastering agar techniques is your first critical milestone. It not only enables you to observe the growth of mycelium but also aids in the selection of strong, contamination-resistant strains. Agar is where your expertise and attention to detail lay the groundwork for everything that follows in your cultivation journey.

Liquid Cultures

What is a Liquid Culture (LC)?

A Liquid Culture (LC) is a nutrient-rich solution used to propagate mycelium, the vegetative part of fungi. It is made by adding certain sugars and nutrients to water, creating an environment where mycelium can grow and multiply. This medium is then inoculated with spores or a sample of existing mycelium to start the growth process.

Compared to agar, liquid cultures offer the advantage of quicker mycelial expansion and ease of use. However, they are more prone to contamination and it's harder to identify such issues early on, unlike the agar plates where problems are visible.

How to Make Liquid Culture

Making your own liquid culture is a simple but precise process that involves mixing nutrients into a sterilized water solution and then inoculating it with mycelium or spores.

  1. Prepare Nutrient Solution: Combine water with nutrients like malt extract or dextrose in a jar with gas exchange and injection port. Sterilize the mixture by pressure cooking it at 15 PSI for 30 minutes.
  2. Cool Down: Allow the pressure cooker to naturally depressurize and cool down. Once cooled, take the jar out and let it cool to room temperature before inoculation.
  3. Set Up Sterile Workspace: Before inoculating the nutrient solution, ensure that you're working in a clean and sterile environment. This often involves wiping down surfaces with isopropyl alcohol and using a laminar flow hood or still air box.
  4. Inoculate the Solution: Use a sterile syringe to transfer spore solution or mycelium from an existing culture into the nutrient solution. Do this carefully to avoid contamination.
  5. Seal and Stir: Tightly seal the jar and mix (magnetic stir is ideal) it to distribute the mycelium or spores evenly throughout the liquid. Be careful not to allow the liquid to touch the filter patches.
  6. Incubate: Place the jar in a warm, dark area at around 75-80°F (24-27°C) to allow the mycelium to grow.
  7. Monitor Growth: Check the jar daily for signs of mycelial growth, which will appear as cloudy, white patches in the liquid.
  8. Stir Again: Once considerable growth is observed, shake the jar again to break up the mycelium and promote further colonization.
  9. Test for Contamination: Before using your liquid culture, double-check for any signs of contamination such as strange colors or odors.
  10. Use or Store: Once satisfied with the growth and purity, you can use the liquid culture to inoculate your substrate, or store it properly for later use.

LC Shelf Life & Storage

Liquid cultures have a limited shelf life, generally lasting around 2 to 3 months when stored properly. It's crucial to store them in a refrigerator at temperatures between 35-40°F (2-4°C) to prolong their viability. Signs of contamination or changes in color and consistency indicate that the culture is no longer usable and should be discarded.

How to Obtain Spores & Mycelium Cultures

There are multiple avenues for acquiring mushroom spores and mycelium cultures, each with their pros and cons. They can be obtained from reputable vendors, collected from wild specimens, or even carefully isolated from store-bought mushrooms. Your choice will depend on your level of expertise, the specific mushroom species you're interested in, and your focus on either ease of use or hands-on involvement.

Reputable Vendors

Buying from trusted vendors is perhaps the most straightforward method of acquiring spores and mycelium cultures. These vendors offer high-quality, contamination-free samples that can give you a head start in mushroom cultivation.

  • Spore N' Sprout: It's my first stop when I'm hunting for new cultures. They offer clean, affordable options, and quick delivery.
  • Fresh From the Farm Fungi: Gary is an excellent mycologist. Every culture I've snagged from him has been stellar.
  • North Spore: A leading brand in the world of mycology. I've purchased spawn and grow kits from them with excellent results.

Wild Harvest

Collecting spores from wild mushrooms is an adventurous but risky approach. It requires a good deal of expertise in mushroom identification and sterile technique. I do not recommend this method for beginners due to the high risks of contamination and potential for misidentification.

Grocery Store

It may surprise you to know that you can, in fact, source mycelium from store-bought mushrooms. However, this approach is less than ideal due to potential contaminants and the narrow range of species available. If you opt for this method, a strict sterile technique and the transfer to a controlled medium like agar are essential.

Recommended Culture Equipment & Supplies

The right equipment is crucial for success in mushroom cultivation. You can find a list of supplies I personally use and recommend on my equipment page.

Equipment & Supplies I Use
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Mushroom Cultivation