Plastic Bag Alternatives

My brother and I are looking at setting up a small side-business and we too are bothered by all the potential waste. We're looking at starting with a strain or two of oyster mushrooms. From what I've seen, some commercial ventures use 5lb plastic bags of substrate, then dispose of the bag. Would something like this 4 litre tub not be suitable? It's clear, easily drilled, can be sealed, and can be chemically sterilised (not sure if they can be autoclaved though. Can anyone think of any objections to using them, except the initial cost outlay?  https://oipps.co.uk/4-l-crystal-square-tub (ps I live in the UK, which is why it is a UK site).

If I'm not totally wrong PP can be sterilized in a pressure cooker.

I would advice to just by a bunch and do a test run against some of the standard bags.

As far as I know the bags are used because they are quick in handling. Time is a lot of money if you have to pay wages ;)

I don't know anything about growing mushrooms, but could you "recycle" used animal feed bags? Heavy duty plastic, meant to hold weight, and you'd probably be getting them for free and taking them out of the waste-stream...

Don't think so as the bags need to be air / microbe tight with a filter port for gas exchange.

It would take a lot of work to test for holes and install a filter port.

But the biggest problem: Does the plastic withstand sterilization?

Dominik Riva wrote:Don't think so as the bags need to be air / microbe tight with a filter port for gas exchange.

It would take a lot of work to test for holes and install a filter port.

But the biggest problem: Does the plastic withstand sterilization?

Not sure if we're looking at the same product. These are plastic food grade boxes with lids; unlikely to have holes in them and the lids will be airtight. I've not seen ports on commercial bags, only those home grow kits. From what I've seen they just spawn in the bags which are then ripped open for fruiting. I had an idea for the boxes wheresterile tape over the holes, then removed when fruiting. Also, as someone else pointed out, they're PP, so can be heat sterilised.

Polypropylene (pp) is a translucent plastic. It has the capacity of withstanding maximum temperatures of up to 135oC (275oF).
It also has a brittleness temperature (temperature where the plastic may crack or break if dropped) of 0oC (32oF).
Polypropylene possesses a low impact strength.
However, it has excellent compatibility with concentrated or weak bases, acids and alcohol (has a capacity of withstanding any damage from such chemicals for a period of 30 days, constant exposure).
Due to its characteristics, this polymer is most often used in making vials, bottles, pumps, clothing and funnels.

So, yes PP can withstand the autoclave (pressure cooker).

Those containers can be set up to work for growing mycelium and with well thought out holes for the fruits to exit they would make good, reusable containers for growing mushrooms.
You would need to have them in a room set up similar to a clean room to prevent contamination of the growing medium though.

Redhawk

Bryant RedHawk wrote:

Those containers can be set up to work for growing mycelium and with well thought out holes for the fruits to exit they would make good, reusable containers for growing mushrooms.
You would need to have them in a room set up similar to a clean room to prevent contamination of the growing medium though.

Redhawk

I would advice against the holes and clean room.
It is way easier to keep the contents of the containers sterile then a room.
Install some filter ports for spore free gas exchange - polyfill or cellulose filter disks.

Use the resulting containers to colonize the medium and if pins form dump the block on a rack in a fruiting room - not a clean room but high humidity and ideally HEPA filtered blower that pumps air into the room to produce over pressure.
Be careful not to push the spores from the fruiting room into living quarters and please wear a mask in there as you will get allergic to the spores over time if you don't.

Dominik Riva wrote:

Bryant RedHawk wrote:

Those containers can be set up to work for growing mycelium and with well thought out holes for the fruits to exit they would make good, reusable containers for growing mushrooms.
You would need to have them in a room set up similar to a clean room to prevent contamination of the growing medium though.

Redhawk

I would advice against the holes and clean room.
It is way easier to keep the contents of the containers sterile then a room.
Install some filter ports for spore free gas exchange - polyfill or cellulose filter disks.

Use the resulting containers to colonize the medium and if pins form dump the block on a rack in a fruiting room - not a clean room but high humidity and ideally HEPA filtered blower that pumps air into the room to produce over pressure.
Be careful not to push the spores from the fruiting room into living quarters and please wear a mask in there as you will get allergic to the spores over time if you don't.

Thank you for this helpful info. If using these boxes, would you advise mixing the sterlised spawn medium (grain for instance) directly with the substrate, inoculating and then leaving to colonise OR inoculating and colonising the spawn first before mixing with the substrate?

I'm not sure if I understand you right.

Some principles may help answer your question anyway:

Colonize in stages to minimize contamination.

Transfer to the next medium before the mycelium has depleted the nutrients - this will inhibit premature fruiting.

Never mix sterilized medium with the next stage/medium/substrate - mix colonized medium with the next stage/medium/substrate.

A typical chain form spore to production looks like this:

Spore print

Petri dish

Petri dish

Petri dish

Petri dish - pure strain is archived and samples get labeled and archived in a fridge

liquid culture - optional

grain

grain

grain

Masters Mix / straw / coffee grounds / wood chips / What ever the fungi can eat

Some additional hints for the chain above:

toss the strains form your archive that didn't do well for you

proven strains go from archive fridge to Petri dish from there you fork them back to archive but increase the p-number and to production via grain

if production with high p-number strains get weak go back to lower p-numbers of the same strain to refresh the vigor

refresh strains in the archive fridge at regular intervals and have a backup off premise

In all of this steps except the spore print the medium needs to be sterilized - Aluminum foil is practically sterile from the heat of production.
The last stage is often sterile but not always as some contamination at the last stage can get easily overwhelmed by the mass of mycelium added - especially if robust fungi like oyster mushrooms are used but can easily reduce yield.
Straw or wood chips or fresh spend coffee grounds get often pasteurized or in the case of coffee ground come pasteurized.
Transfers need to happen as sterile as possible (flow hood or still air box).
The better your sterile practice the more you can dilute the mycelium in the next medium - in the Petri dish stages you always want to get the least amount of material to the the next Petri dish to purify the strain as fast as possible.

Good luck with your business

Dominik Riva wrote:I'm not sure if I understand you right.

Some principles may help answer your question anyway:

Colonize in stages to minimize contamination.

Transfer to the next medium before the mycelium has depleted the nutrients - this will inhibit premature fruiting.

Never mix sterilized medium with the next stage/medium/substrate - mix colonized medium with the next stage/medium/substrate.

A typical chain form spore to production looks like this:

Spore print

Petri dish

Petri dish

Petri dish

Petri dish - pure strain is archived and samples get labeled and archived in a fridge

liquid culture - optional

grain

grain

grain

Masters Mix / straw / coffee grounds / wood chips / What ever the fungi can eat

Some additional hints for the chain above:

toss the strains form your archive that didn't do well for you

proven strains go from archive fridge to Petri dish from there you fork them back to archive but increase the p-number and to production via grain

if production with high p-number strains get weak go back to lower p-numbers of the same strain to refresh the vigor

refresh strains in the archive fridge at regular intervals and have a backup off premise

In all of this steps except the spore print the medium needs to be sterilized - Aluminum foil is practically sterile from the heat of production.
The last stage is often sterile but not always as some contamination at the last stage can get easily overwhelmed by the mass of mycelium added - especially if robust fungi like oyster mushrooms are used but can easily reduce yield.
Straw or wood chips or fresh spend coffee grounds get often pasteurized or in the case of coffee ground come pasteurized.
Transfers need to happen as sterile as possible (flow hood or still air box).
The better your sterile practice the more you can dilute the mycelium in the next medium - in the Petri dish stages you always want to get the least amount of material to the the next Petri dish to purify the strain as fast as possible.

Good luck with your business

Thank you so much again; very helpful.

I think I will be going with the clean-room setup when I go for this. It is a project for after the move out of the city, where I will actually have a room to use this way.

I don't see the logic in not going the clean-room route. I mean, I would do all the same things as if I was simply sterilising the containers. The room would just be an added barrier to contamination, and a layer of protection between my living/working space and mushroom growing.

You need to sterilise the room before you open the grow containers anyways. This is just a way to keep the space cleaner and clear of obstructions. If I need to grow more mushrooms to justify all the additional space used, so be it. More mushroom compost for other activities.

And more mushrooms. Along with onions and garlic, we have mushrooms with almost all of our dinners, and most lunches, too, as those are usually leftover-derived.

Good luck to you, Benjamin. Pictures are always appreciated whenever you have something you'd like to share. Keep us posted.

-CK

Chris Kott wrote:I think I will be going with the clean-room setup when I go for this. It is a project for after the move out of the city, where I will actually have a room to use this way.

I don't see the logic in not going the clean-room route. I mean, I would do all the same things as if I was simply sterilising the containers. The room would just be an added barrier to contamination, and a layer of protection between my living/working space and mushroom growing.

You need to sterilise the room before you open the grow containers anyways.

There is a distinction between an clean-room and a fruiting room. The fruiting room will get filled with spores of your desired mushrooms and the clean-room needs to be devoid of any mushrooms as this is the only way to control what you are growing.
A clean-room does not need to be permanent structure as in its minimal form it can be a dust free room with a still air box to work in. The next level is using a laminar flow to work in front of.

You don't need to sterilize the room before you expose fully colonized blocks for fruiting - the last stage is quite forgiving. Clean practice is advised in a fruiting room but nothing compared to the ritualistic levels needed for a clean-room.
There is a reason mostly big labs have actual clean-room. The time it takes only to get through the airlocks is crazy. Most labs use a laminar flow hood.