Fungal Genetics Preservation Made Simple

Mushroom growing starts with curiosity and can quickly become a passion. Like in any other cultivation niche, once you enjoy success, you’ll find endless directions to take your new skills and knowledge. Should you try a similar variety or challenge yourself with more complex projects? Is it personally rewarding to falter in an ambitious leap into new territory and learn from the experience? Or is it better to fine-tune your techniques and improve the quality and yield of a familiar crop?

To see the future, look to the past

Until recently, obtaining viable and trustworthy samples of new mushroom starting materials was challenging. The back pages of subculture magazines advertised kits for risk-tolerant underground growers, and online communities of traders arranged swaps and illicit sales. Caveat emptor was always in effect because even those with good intentions and well-developed skills couldn’t make any formal guarantees. Outside of these psychedelic-oriented online niches, seekers of new and interesting mushroom experiences had to go foraging IRL. They took to the forest, the field, or restaurants with knowledgeable chefs, speciality grocery stores, and traditional medicine practitioners.

While these options are still accessible today, habitat destruction and increased demand drive economic incentives and the everyday person’s rationale for growing their food and medicine.

It’s good that beginners can find more mushroom-specific suppliers for the basic equipment and materials for home growing and that do-it-yourself, small-budget, and grassroots knowledge-sharing are built into the mycophile milieu. 

Direct-to-consumer sales of spores and culture syringes remain largely a cottage industry, with regional specialists offering cloned local varieties alongside commercially proven strains.

If you have the financial means, you can access any mushroom culture you wish via these online vendors. Aside from concerns about the legality of certain fungi, shipping logistics (e.g. distance and in-transit environmental factors) are the main threats to the viability of purchased (or traded) specimens for starting your own grow.

You’re likely to find there are particular fungal species or subtypes that you want to keep on hand. It may not always be the “right time” to grow a certain mushroom due to environmental conditions beyond your control, or your dedicated cultivation space is in rotation, keeping some species on the bench while others are in play.

Whether or not to keep a strain archive, if there is nothing extraordinary about genetics, is a question of resources and mindset. Like gardeners, mushroom growers come from all walks of life. Financial circumstances can change without warning, and infrastructural failures, weather anomalies, or other disruptions to a production schedule can threaten entire seasons’ worth of effort.

Cultivators need only look to the recent history of plant agriculture to imagine how access to favourites can become threatened by ecosystemic biodiversity loss, DNA patenting and engineering, changes to laws and their enforcement, and global supply chain disruptions. Food security researchers agree that seed saving at the local level should be supported “actively and at scale”, informing our approach to preserving beneficial strains of fungi.

Acquire it once, grow it forever

Like heirloom or heritage plants, unique fungi strains can become a dependable standby or signature of your seasonal offerings. It could be the match is physiological, the partnership especially beneficial to your health or suited to your taste. Perhaps it’s practical, and the working relationship is smooth and fruitful. Though eternity may be elusive, regenerative techniques may work to keep that special companion in your life for more than a season or two.

So, how can a grower hold onto their mushroom genetics? Is it worth the effort?

Always Be Copying

You’ll only know if a strain is exceptional once you’ve grown it out. By this time, unless you’ve kept some of the original stock in good health, it will be more difficult to copy it.

The first time you do a liquid medium inoculation, hold at least half of the commercially-made syringe in reserve by keeping it in a sealed container in a fridge. Undisturbed in this cooler temperature range, cultures have been reported to survive for many months, even years. Consider this your “vault” and hope you don’t need to use it.

Before you move on to grain inoculation, use your first jar of living culture to make at least one more. Fill the syringe again, sterilise the needle, label it and put it in the vault. You can expand a liquid culture repeatedly if it remains uncontaminated.

Propagation of mushrooms is similar to rooting cuttings from well-known donor plants; vigorously growing cultures are more apt to thrive, overcome adversity, and produce abundant yields.

In properly-made jars with filtered airflow (so the broth can be aerated and carbon dioxide made by the mycelium can escape) and self-sealing injection ports, many common mushroom species will rest comfortably at room temperature in a dark cupboard for several months.

Before sealing and sterilising jars of your chosen liquid medium, include a glass marble. This is critical to maintaining the usability of your culture; “habit stack” agitating the culture with another regular routine, like making your first cup of coffee in the morning. A minute of swirling the marble around the bottom of the jar keeps the broth full of fresh air and breaks up the mycelium, encouraging it to keep growing and preventing the formation of a static, floating layer (it’ll resemble a kombucha SCOBY or even start trying to fruit, and make it more difficult to suck up into another syringe for propagation).

Multiply both the initial culture and the first copy you made at the same time. Experimentation with substrate recipes is one way to vary the pace and reveal opportunities for value-adding (or cost-saving) by using what’s on hand. Examples include birch or maple sap in liquid cultures or bulk seed intended for feed or cover crops in grain cultures.

In bigger root cellars, research suggests mycelium living on sorghum grain can be held in reserve between 5-8°C for more than one year, free from contamination and without any growth and morphological changes.

Set it free

Similar to a passionate sourdough baker always trying to use up their discard and give it away to anyone who’ll provide a good home, it’s inevitable that you will have more copies than you can rationally manage. Thankfully, redundancy is a great way to release that cherished cultivar into the community and invite the possibility of a future reunion. 

Born to be wild

Mushroom beds, with substrates replenished regularly with adequate nutrition, are a “living library”. Similarly, inoculated stumps and logs preserve a strain specimen for as long as it can feast on the wood without being overtaken by competitors. Either type of permacultural installation can serve as a genetic reserve, and exposure to adversity may even push a common strain to adapt for survival in local conditions.

Using robust fruiting bodies as source material for cloning is one way to (re)capture and perpetuate a favourite strain. Taking and archiving spore prints is a lower-barrier but riskier way to save such genetics.

Take it to the Bank

Perhaps it won’t be long before the mainstreaming of home mushroom cultivation inspires the proliferation of genetics banks and community libraries. In parallel with seed-saving initiatives, conserving a diversity of spores and live cultures is a noble endeavour. Preserving locally adapted mushroom genetics of all types promotes and supports wellness practices at the individual and community levels. It’s in the public interest to integrate fungi into existing food and medicine sovereignty initiatives and to continue spreading education and access. 

Save your faves, bond with others through trades, and be generous with your knowledge! 

Tips for Strain Savers

Do:

• Collaborate with others in your network when ordering new strains to take advantage of better pricing and make local trading more interesting and resilient.
• Stock plenty of extra empty syringes if you have the means. Make putting backup syringes in the vault part of your production schedule.
• Label every container with a minimum of the fungal species name, origin, and date.
• Keep meticulous records of your activities, from strain acquisition through inoculation, expansion, and harvest.
• Choose a regular interval to refresh your inventory of cultures in storage, and mark it on the calendar or set an alert.

Don’t:

• Assume you can purchase the same genetics again, even if the vendor is still in business.
• Become overly emotionally invested. A lost genetic may be grieved, but you’ll find another to take its place. Get by with the help of your friends!

References:

Deuss, A., C. Gaspar and M. Bruins (2021), “The impact of the COVID-19 pandemic on global and Asian seed supply chains”, OECD Food, Agriculture and Fisheries Papers, No. 168, OECD Publishing, Paris, doi.org/10.1787/e7650fde-en.

Sperling, L. Seed security response during COVID-19: building on evidence and orienting to the future. Food Sec. 12, 885–889 (2020). doi.org/10.1007/s12571-020-01068-1

Veena SS, MeeraP 2010 – A simple method for culture conservation of some commercial mushrooms. Mycosphere 1(3), 191–194. rebrand.ly/d20350