How to use the Microsacs correctly?

In order to use the Microsac correctly, please follow the procedures below!

1. Moisture content of the substrate mixture:

Excessive moisture content inhibits satisfactory gas exchange. Observe the following standards:

  • for grain spawn: ± 42% moisture
  • for substrate for exotic mushrooms: ± 62% moisture

2. Filling the Microsacs:

Microsacs should be handled with care.  Damaged bags should be removed because of the subsequent risk of infection through even small clefts or holes.

3. Stacking method during heat treatment:

  • preferably put the Microsacs upright
  • make sure the filters do not touch each other

4. Heat treatment:

Continue long enough, and at a sufficiently high temperature .

  • Sterilization is done in an autoclave which is kept at a temperature of 121°C for several hours until the center of the most centrally positioned sac remains at 121°C for a continuous period of 10 minutes.
  • Pasteurization takes place at lower temperatures with longer heat treatment but allows less chance of producing an axenic (i.e. uninfected) end product.

5. Cooling the substrates:

In a dry, well-ventilated space.  For open bags that have been folded shut, a supply of aseptic pressurized air is necessary.  For sealed bags, it is advisable.

6. Inoculation:

Under aseptic conditions, i.e. using a Laminar Air Flow (LAF).

7. Sealing the Microsacs hermetically:

Under the same aseptic conditions, by means of a double-sided heat weld.  Sac02 can provide you with such a welding machine, if so required (

8. Incubation phase:

Put the substrates on the shelves so that as much filter surface area as possible is exposed. For satisfactory gas exchange, the CO2-content of the air around the substrates should have a maximum of 2500 ppm (= 0.25%).  Therefore make sure that the following conditions are met:

  • good circulation of dry air, with a continuous supply of aseptic pressurized air.
  • correct incubation temperature: 25 °C is suitable for most types of mushrooms and substrates. We would like to emphasize that the substrate temperature should not become too high, since this will cause the CO2 to be produced faster than it is eliminated, which will result in suffocation of the mycelium.  Accidentally infected substrates must be eliminated immediately as mycelium can grow through the filters.

9. Storage after growth:

For long-term storage, store unpacked in a dry cold storage unit.

The Microsacs have many advantages (see the SacO2 website), the most important of which is their perfectly distributed, adjustable gas exchange.

The intensity of both the gas exchange and the evaporation is determined by the length of the filter wicks.  According to the customer’s needs, the wicks can be easily adjusted during production.

The filter wicks are hydrophobic, yet permeable for gas and vapors. Condensation of vapor in the filters must always be avoided.

If you observe the above guidelines and nonetheless have a problem with damp filters during the production process, our “filter up” Microsacs offer a simple solution to your problem. In these bags, which have no fold at the bottom, the filter strips are situated at the top.

The "filter up" Microsac:  guarantees perfectly dry and clean filters after autoclaving. The lowest filter can in some cases touch the substrate for more efficient steam injection.

In these bags, which have no fold in the bottom, the filter strips are situated on top.  They are filled and sterilized in the lower half, which has no filters, so that condensation in the filters is avoided.

After the sac is inoculated and sealed-shut by welding, the contents of the sac is moved to the end with filters in order to allow a perfect gas exchange.

If you wish to order a small quantity of these bags, click here.

  • Manual for using the Microsacs
  • Manual for using the Microsacs
  • Manual for using the Microsacs
  • Manual for using the Microsacs