Mushroom Spawn 101: Your Ultimate Guide
Before you start exploring this blog about mushroom spawn, It will be really helpful if you are familiar with the basics of what mushrooms are and how they are cultivated. If you’re new to mushroom cultivation, please check out these blogs to know more about how mushrooms grow and the jargon used in mushroom cultivation:
Mushroom spawn is very critical if not the most important input in the mushroom cultivation process. We try to clarify the most commonly asked questions about mushroom spawn in this blog, in order to equip you with the right knowledge. Here is a look at the different questions that we will be addressing:
- What is mushroom spawn?
- Why can’t we cultivate from spores?
- How is spawn made?
- What is the difference between grain spawn and sawdust spawn?
- What are the qualities of good spawn?
- How do we store spawn properly?
- How do we know if the spawn we have is good?
What is mushroom spawn?
Mushroom spawn is basically mycelium, the living fungal culture, grown onto a substrate. It is the most critical input in mushroom farming and is used by mushroom growers similar to how farmers and gardeners use seeds. Mushroom spawn, unlike seeds, is grown from selected genetics and cloned so that it is possible to consistently produce a particular cultivar (cultivated variety) of mushroom which exhibits desired traits. This is similar to how people grow fruit trees via grafting as opposed to planting their seeds. Grafting is done to make sure that the fruit tree consistently produces delicious fruits because of a particular set of genetics that are chosen. Spores (and seeds for that matter!) are a genetic lucky dip dependent on two individual sets of genetic material, whereas spawn is a single, unique genetic culture that can be indefinitely propagated from the same ‘mother’ culture. Our ‘mother’ cultures are kept in the laboratory on agar petri dishes and maintained at the optimal temperature.
Spawn bags being prepped under sterile conditions in the lab
Why can’t we cultivate mushrooms from spores?
In the wild, mushrooms produce tens of thousands of spores (some even billions!) and get scattered across the forest by wind, rain, insects and other agents. They are on a quest to find the most suitable growing conditions but sadly the vast majority of spores will never grow into a mushroom fruit-body. As a cultivator this is not a risk that you can take, you want to ensure that you get consistent, reliable and repeatable results every time.
Another factor to consider is that spores are not sterile and growing using spores directly might lead to an increase in contamination rates which will affect your productivity drastically.
At Nuvedo we select productive strains of edible and medicinal fungi to make spawn which have been proven to give consistent results in the Indian setting, so that our cultivators can maximize their success.
How is spawn made?
All spawn start out their journey on a petri-plate as a pure fungal culture of mycelium. Once the mycelium has fully colonized the surface of the agar, a tiny piece of the mycelium is transferred to boiled grain. This mycelium is then allow to grow on the surface of the boiled grain for 3-4 weeks until it colonizes all of the grain. This myceliated grain is what is called grain spawn.
Apart from different grains such as wheat, jowar (sorghum), millet, rice, etc. some spawn producers even use sawdust and wooden dowels as a substrate for making spawn. The substrate used to make spawn serves three functions-
- Act as a surface for the mycelium to grow and spread on
- Provide the mycelium with macro and micronutrients so that it stays alive and healthy till it is inoculated on the final substrate material
- Act as multiple points for the mycelium to grow from and colonize the final substrate material at a faster rate from different parts of the substrate
We produce all of our spawn at our state-of-the-art facility in Bengaluru. NuvoSpawn is produced on sorghum grain in sterile lab conditions. We start by taking mushroom cultures from our culture bank and then growing them out on sterilized grain in a controlled environment, using our own standardized process and media, to ensure that our customers get the best quality time and again!
To ensure consistent results we grow our own mushrooms at regular intervals and keep track of the cultivation parameters of each and every strain. We do not sell spawn of any mushroom that we ourselves have not grown. If you’re buying spawn for the first time, make it a point to ensure that your spawn vendor grows their own mushrooms to ensure the variety is still performing consistently.
Nonabsorbent cotton plugs being inserted into the neck of the spawn bag inside a Laminar Air Flow
Inoculation of sterilized sorghum with a myceliated agar wedge
Final packing of spawn bag after inoculation under aseptic conditions
What is the difference between sawdust spawn and grain spawn?
Grain contains a lot more nutrition as compared to sawdust. This can lead to contamination or increased chances of attack by pests if used to make outdoor beds or logs. When the cultivator wants to grow in an outdoor environment where there could be pests or where the chances of contamination are higher, sawdust spawn is a much better option. Using sawdust spawn for conventional cultivation can lead to lower yields and slower colonization as compared to grain spawn.
What are the qualities of good spawn?
The most critical parameters for good spawn from a cultivator’s point of view is:
It should be free from contamination
- The spawn has to be made under aseptic conditions preferably under a Laminar Air Flow to ensure the best results
- All materials used must be of the highest quality. Using low-quality or broken grain can lead to increased chances of contamination post inoculation.
- Grain used has to be boiled to the right consistency to ensure that it doesn’t break or get squished post inoculation. This is really important in ensuring low contamination rates.
- Grains/sawdust needs to be sterilized in an autoclave at 121 degrees Celsius and 15 PSI pressure to make sure that no microbial life persists
It should be fast colonizing
- Genetics that are old or not maintained well undergo “senescence” or deterioration, leading to slow growth and poor yields
It should give good yields
It should be free from toxic chemicals, antibiotics, and pesticides
- Some spawn manufacturers have been seen using hazardous chemicals such as formaldehyde to fumigate their labs and some even add antibiotics such as gentamycin to their media to keep it free from microbial contamination
- Over time, exposure to these chemicals can cause detrimental health issues to the cultivator who handles these materials
- Fungi can bioaccumulate complex molecules and the resulting mushrooms may contain trace amounts of these chemicals which will eventually affect the health and wellbeing of the consumer.
It should give consistent results every time
- Some genetics are prone to mutation more than others and this can lead to variation in cultivation parameters such as speed of colonization, physical characteristics of the mushroom itself, and even yields.
Qualities of Good Spawn
We take pride in saying that NuvoSpawn is not just another bag of spawn. It is a technically superior product guaranteed to maximize your success by giving you consistent results time and again. We document the optimal growing conditions of our cultures to ensure that our customers can make the best use of our product.
- Is enriched with first-quality grain which ensures vigorous colonization and healthy growth.
- Is completely dry, pure fungus without wet patches to eliminate chances of bacterial contamination.
- Has been proven to give higher yields due to greater bio-efficiency because of our genetics and unique media.
- Is manufactured in a sterile environment which leads to a healthier growth of fungus.
- Uses disinfected nonabsorbent cotton to reduce chances of contamination.
How do we store spawn properly?
Your mushroom spawn is alive!! Yes, it is a living, breathing organism. In order to keep it healthy, happy, and strong we need to make sure that it is stored properly. A question we keep hearing is “how long can I store my spawn?” How long you can store your spawn depends on 3 things mainly:
- Cultivated variety or cultivar
- Storage Temperature
- Storage Conditions
Factors Affecting Spawn Storage
Let’s take a look at the factors one at a time:
It has been observed that varieties in which the mycelia grow slowly tend to have the longest shelf-life. To put it simply, the slower the growth of the variety the longer you can store it.
There are some basic signs to look for to understand if your mycelia are undergoing senescence or biological aging. The following are signs of the aging process of mycelia, in their order of appearance:
- The mycelia become more compacted
- The appearance of hard-looking crusts or lumps
- Formation of foul-smelling, colored liquid
- Self-digestion or autolysis of mycelium and degradation of mushroom spawn
4 Stages of Spawn Ageing
The mycelium is perfectly healthy and usable in stages 1 & 2 through the spawn might not feel as crumbly as it does when it is fresh. Self-digestion or autolysis starts happening at the end of stage 3, hence it is strongly recommended that you use your mushroom spawn before it happens. The mycelium has reached the end of its life in stage 4 and therefore the spawn should be discarded at this stage.
The ideal temperature for the storage of spawn is 0 to 4 degrees Celsius. At this temperature, spawn can be stored for anywhere from 2 months to 4 months. However, there are a few exceptions to this, for example, Pink Oyster mushroom spawn or Milky mushroom spawn tend to degrade if refrigerated since they are both tropical varieties.
If you have ordered boxes of NuvoSpawn, make sure that you place the boxes on shelves or stack them in an alternative manner like bricks, always making sure that you leave around 10 cm space between the boxes for airflow. If spawn for mushrooms like oysters has to be stored for extended periods, then take out each bag from the box and put them separately on the shelves inside the refrigeration unit. The refrigeration unit will have to be opened on a daily basis to ensure there is enough circulation of fresh air for spawn survival.
We strongly recommend you not to order or store your spawn months before the actual date of use. Whatever money you may save on shipping will be compensated by an increased yield and lower chances of contamination losses using fresh spawn.
At Nuvedo we do not keep any spawn that has aged more than 3 weeks to ensure that our customers get the best results, so it becomes really difficult to entertain last-minute requests as we are almost always booked out. The best-case scenario for us would be if you let us know 14-21 days before you need your spawn so that we can ensure the availability of fresh spawn. We will ship it out to you exactly in time for your inoculation!
How do we know if the spawn we have is good?
So, you’re waiting on your first batch of NuvoSpawn from Nuvedo or have a batch of mushroom spawn that you’ve been storing for a while now?
Without testing, you might have to inoculate your substrate and then wait a few weeks to come to the realization that the spawn you used was too old or not strong enough. To save yourself all that trouble you now want a quick and easy method to see if you can proceed with inoculation without worrying if the spawn you used was good enough. Well, you’ve come to the right place, all you need to do is follow the instructions mentioned below!
There are 2 ways of doing this, the hard way (which gives you more reliable results) or the easy way (which is cheaper and requires a lot less effort)
Let’s start with the easy way:
- Take a sample of a few grams of spawn from each bag you wish to test.
- Take a clean plastic container and put a small pile of wet paper (tissue paper, toilet paper, cardboard) on it.
- Place the spawn on top of the paper.
- Place the container in a clean, cool place away from direct sunlight.
The mycelium should be growing visibly on the paper in less than a week. This method is not foolproof and can give you false results so we would recommend you to follow the technique mentioned below.
The hard but reliable way:
- Take a petri dish that has been prepared with PDA or MEA mixture.
- Open the dish under sterile conditions, preferably under a laminar airflow, to avoid contamination. (Contamination can give your false results)
- Using a sterile tool, such as a spoon sterilized under a naked flame, place a few kernels of mushroom spawn around the petri dish.
- Under the laminar air flow, roll the kernels around under the petri dish. Close and label the petri dish.
- Let the petri dish mature for 5 days to a week at a temperature beneficial for mycelium. We recommend around 20 Degrees for Oyster mushroom spawn or Shiitake mushroom spawn.
In a week you should observe mycelium growth from the place where the kernels were rolled over the agar medium and from the kernels themselves
The result: The strength of the spawn is indicated by the amount of mycelium growth present after a week. If the growth is fast and intense, your spawn is still very active. Old spawn also has a capacity to colonize the substrate like fresh spawn but the rate of growth will be much slower. So, the same applies to the kernels on your petri dish/paper towel. If you don’t see any growth in 5 days or so then that means that your spawn is too old and needs to be discarded. It is not that old spawn will not be active, it grows so slowly that contaminants get the upper hand and might take over your substrate. So, better safe than sorry.
Now that you have checked your spawn quality, you can confidently proceed with the next steps of mushroom cultivation if your test results came out well or order a fresh batch of NuvoSpawn in case your spawn is too old.
This brings us to the end of this blog, if you have any further questions or need any clarifications about spawn, feel free to reach out to us. We are more than happy to answer your queries.