Optimizing the growth and yield of any mushroom starts with a high-quality mycelium. Today’s research paper investigated several different agar media for the cultivation of Agrocybe aegerita, better known as the Black Poplar Mushroom. This mushroom grows in nature on living and decaying stumps of trees such as poplar, willow, black poplar, ash, elderberry, black locust, and Brazilian araucaria.
In the first experiment, the authors tested mycelium growth on 8 agar media. These were PDA, standard, wheat, MEA, CYM, PCA, sawdust extract of alder, and a mixture of beech and birch with a 1:1 ratio. The mycelium was incubated at 25°C and 80% to 90% relative humidity.
The authors found the highest mycelium growth rate with 7.3 cm on PDA, 7.2 cm on MEA, 7.1 cm on wheat, and 7.1 cm on the mixture of birch plus beech. Each of the results was taken after 9 days which gives us the following growth rates. 8.11 mm/day for PDA, 8.00 mm/day for MEA, 7.89 mm/day for wheat and the mixture of beech plus birch. The lowest growth with 5.78 mm/day was found on CYM.
In the second experiment, the authors tested mycelium growth on 5 sawdust extracts: from birch, beech, oak, maple, and alder. The sawdust was moisturized up to 70%. After sterilization, the cooldown, and inoculation, the tubes were incubated at 25°C and relative humidity of 85% to 90%.
The authors found the highest mycelium growth with 7.1 cm on beech, 6.8 cm on birch, and 6.7 cm on alder. As each result was taken after 18 days, we will get the following growth rates. 3.94 mm/day for beech, 3.78 mm/day for birch, and 3.72 mm/day for alder. The lowest growth with 2.22 mm/day was found on oak sawdust.
The authors then cultivated the poplar mushroom on three kinds of sawdust substrates; birch, beech, and a mixture of beech plus alder (ratio 1:1). After the substrate was fully colonized, the temperature was dropped down from 25°C to 15°C. Lighting was applied for 10 hours per day at 500 lx. The mushrooms were harvested and yielded 39.5g/100g DM, the highest value for the mixture of beech + alder. Followed by 36.8g/100g DM for birch. Only 8.7g/100g DM could be harvested on beech sawdust.
With these numbers in mind, we get a good sense of selecting the suitable culture media and substrate. To see this process in action, let us start with the culture media and sort them according to their growth rates. Next up is the used culture media for the second experiment. Here, we already see that the authors did not use, for example, PDA or Wheat even if they even had similar or even higher growth rates.
My assumption is that they used them only as a reference.
The mycelial growth rates showed similar results in comparison with the first experiment. Interestingly, the growth rate on beech could not be enhanced by adding birch. The authors then went on and tested the following substrates. They tested beech in combination with alder and alone and compared them to birch.
The results here indicating that beech alone leads to a low yield. Adding alder increases it, but we do not know how well alder alone would perform. For me, it seems that alder would be the better substrate in comparison with beech. If it would outperform birch is unfortunately unknown to us.
Making these kinds of analyses helps us to understand the connection between culture media and substrate. Besides, we see the missing information which would be needed to make better-informed decisions.
Talk to you in the following video.
📝 Jasińska, Agnieszka & Siwulski, Marek & Sobieralski, Krzysztof. (2012). Mycelium Growth and Yielding of Black Poplar Mushroom-Agrocybe aegerita(Brig.) Sing. on Different Substrates. Journal of Agricultural Science and Technology A. 2. 1040-1047.