Using Sterilised Rye Grain for Spawn

Starting with the basics

Sterilised Rye Grain bags
Our sterilised rye grain bags contain fully sterilised and optimally hydrated rye grain and nothing else! We use rye grain as it is an optimum choice for producing mushroom grain spawn. The bags are heat sealed with injection ports added after sterilisation and are ready for inoculation with liquid culture, which you provide yourself.

Inoculation
Inoculation refers to the process of injecting it with an inoculate such as liquid culture, which you can think of as ‘seeding’ the grain with live mycelium.

Mycelium
Mycelium is what mushrooms grow from and tends to look a bit like white mould as it grows and takes over your grain. Mycelium can be grown directly from spores, by cloning live mushrooms or cloned from existing mycelium in either agar or nutrient liquids. When buying online, you find most types of mushroom mycelium available as liquid culture syringes.

Spore Syringes
We always advise against the use of spore syringes because (1) cultivation is much slower than when using liquid mycelium culture and (2) the risk of contamination is significantly higher.

Liquid Culture Syringes
Liquid culture syringes for most types of mushroom are readily available online. Liquid culture syringes contain live mycelium in a nutrient solution.

Colonisation
When mycelium is added to a suitable food source such as sterilised rye grain it grows and colonises the grain. Over several weeks your grain will slowly change appearance until it is fully covered with healthy white live mycelium. This is what we mean by colonisation.

Using All in One Grow Bags

Basic process
The process of producing grain spawn starts with inoculating the grain with liquid culture.  Once inoculated, mycelium slowly starts to grow and spread out into your grain, looking a bit like white mould invading the bag. This is what you want to see!

Once the grain is about half colonised, you should use your hands to gently break up the colonised grain and mix it inside the bag with the remaining uncolonised rye. DO NOT open the bag at this stage! Once all the grain has been colonised you will be left with what seems to be a single solid block of grain covered in white mycelium. Any other colours are bad news. At this point your grain can be broken up again and mixed with your chosen substrate in whatever containers you are using. Colonisation is not a quick process, so patience is always needed.

Help yourself – Keep records

One of the biggest struggles mushroom growers have to face on a daily basis is preventing contamination from  creeping in to their grows. It can happen to anyone at almost any time (ask Jeremy Clarkson), and you need to take great care to avoid it. When contamination occurs, because it will, sooner or later, being able to work out how it occurred will help you prevent further outbreaks in the future.

Our rye grain packs are fully sterilised to eliminate any lingering contaminants and are ready to be inoculated. However, to allow you to be certain the grain is ‘clean’ you should set aside your grain for a full week, leaving them in a cool location away from sunlight. As any contamination will be visible 3-7 days after occurring, this wait allows you to confirm the grain’s sterility. This knowledge will help you to trace where any subsequent contamination came from. The vast majority of contamination, if not all, is caused by lapses in sterile working practices, contaminated inoculate syringes (or needles), incorrect handling or unsuitable environmental conditions. Keeping a simple log of everything you do should allow you to trace when any contamination was introduced.

Note that we do not provide replacement bags or refunds for grain that has been inoculated, so these checks are most definitely in your best interests.

Step 1 – Preparation

Down to the nitty gritty….  when using sterilised rye grain bags,  clean your hands, all surfaces and all the equipment you will be using with 70% alcohol before you start inoculation. If you have them, wear disposable nitrile gloves and facemask if available.

Step 2 – Inoculation
For inoculation you require Mycelium liquid culture which is supplied in syringes if you don’t make it yourself. Remove the syringe from its packaging and attach the needle – which you must avoid touching. If you are re-using a needle, flame sterilise it (red hot) before use and cool it by pulling in and ejecting a small amount of liquid culture.

Disinfect the black injection port on your grain bag with a sterile wipe. Shake the syringe a few times to distribute the mycelium evenly, inject 5-10ml of culture into the bag via the injection port. Move the needle around as you inject, so as to send the liquid culture to different areas of the grain. You can attach a strip of tape over the injection port after use, to prevent it getting knocked off and exposing the hole made by the syringe.

Carefully pull air into the top of the bag by pulling the neck gussets apart, allowing a small amount of air to enter the bag via the air filter – never touch the filter itself.  Pulling the gussets apart around the filter will cause air to be drawn inside, and mycelium needs a little air to be able to grow. Make sure there is a small open space behind the filter so that air can enter the bag – there’s no need for a lot of air as more will be drawn in naturally over time. Do not handle your bag roughly, as this can cause holes and tears to appear, especially around folds, seams and creases. Getting over-enthusiastic can lead to burst bags or digging holes with your fingernails.

Find a space where your all in one bag can sit undisturbed, out of sunlight and at a constant 19-23C (the exact incubation temperature depends on the species of mushroom you are growing). Airing cupboards are rarely a good idea as temperature will vary significantly. Leave the bag undisturbed for one to two weeks before being tempted to check progress.

Finally, store your grain bag in a plaace where temperature can be kept constant at around 20-23C depending on the exact mushroom species and away from sunlight. Leave it undisturbed for two weeks.

Step 3 – Mixing

After one to two weeks, the first signs of colonisation will appear. Grain bags colonise from the inside out, so signs can take a while for colonisation to be visible – usually around 2 weeks. The first signs are white blotches around your grain, which will be mycelium growing.

Once the grain is at least 50% colonised, gently manipulate the bag to loosen up the colonised grain and mix it with the remaining uncolonised rye grain. This speeds up the second part of colonisation. Don’t be worried if the white mycelium seems to vanish as you doo this – it’s normal.

Leave your grain for another week or two to fully colonise, at which point it will resemble a solid block of grain, covered in mycelium. It doesn’t hurt, at this point, to leave the bag alone for a further 5-7 days so that any unseen areas that haven’t been colonised have a chance to catch up. When introducing spawn to substrate, you don’t want any uncolonised grains.

Step 4 – Grain spawn is ready to use..

Once your rye grain is fully colonised it’s ready for whatever you have planned for it. Whether you plan to mix your grain spawn with substrate in a container or add it to fresh grain in order to make more grain spawn, be sure that you follow strict sterile working practices at all times. Although your colonised grain is about as contamination-resistant as it will ever be, it is not bulletproof. Putting it into non-sterile containers or using non-sterile tools will always end badly!