Image: Pleurotus ostreatus (Oyster) mycelium after 7 days of growth on denim textile waste.
On what kind of waste can mycelium grow ?¶
To determine which strain would grow on which substrate, I made some experiments of growing their mycelium on different mixtures. During Week 9: textile as scaffold, I carried experiments and the outcomes were that Reishi mycelium could grow on a mix of denim textile and butternut peels foodwaste.
However, in this early stage of experimentations, I did not design my protocols optimally and for instance, I did not have the adequate controls to compare the growth speed of each substrate to a reference, and I could thus not be sure if the fact that the experiment functionned was an artefact or not.
First attempt (20/02/2021)¶
Ganoderma lucidum (Reishi)¶
Image: Reishi mushrooms, from GroCycle.
Goals Try different foodwastes as substrates and witness the effect of a separator between the substrate and the mycelium for easier separation when making aerial mycelium.
Bibliographic resources Pure mycelium aerial hyphae growth protocol, Mycelium growth on textile and food waste experiment.
Material and methods
- Preparation of the foodwaste and textile waste
Foodwase was previously prepared by drying potato peels, butternut peels and avocado skins in an oven for 24hrs at 45°C, then grounded into powder in the food grinder of Fablab Barcelona or shredded using a hand mixer. This way, the foodwaste can be stored for a long period of time. Denim textile waste was used. Textile waste was shredded to small pieces in a textile shredder then blended with a food blender.
| Malt agar | Potato peels and textile waste | Butternut peels and textile waste | Avocado skins and textile waste |
|---|---|---|---|
| 200 ml deionized water; 4 g agar; 4g malt extract | 100g wet potato peels (soak 30g of potato peels powder in 100ml deionized water); 65 g wet textile waste (soak 15g shredded textile in 100 ml deionized water and blend it) | 30 g wet butternut peels (same ratio as for the potato peels recipe); 25g wet textile waste (same ratio as for the potato peels recipe) | 30 g wet avocado skins (same ratio as for the potato peels recipe); 25g wet textile waste (same ratio as for the potato peels recipe) |
Table: Petri dishes composition.
Six different petri dishes were made. This flat growth experiment is actually divided in two experiments:
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The impact of the tulle separator on the growth of the mycelium was tested on two conditions: malt agar and potato peels + textile waste. This experiment thus concerns petri dishes 1 (positive control), 2, 3 and 4.
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3 different foodwastes mixed with denim textile waste were tested: potato peels, butternut peels and avocado skins. This experiment thus concerns petri dishes 1 (positive control), 3, 5 and 6.
| Petri 1 | Petri 2 | Petri 3 | Petri 4 | Petri 5 | Petri 6 |
|---|---|---|---|---|---|
| Positive control: malt agar. | Malt agar and tulle separator. | Potato peels + textile waste. | Potato peels + textile waste + tulle separator. | Pumpkin peels + textile waste. | Avocado skins + textile waste. |
Table: petri dishes numbers and composition.
Due to the necessity of keeping sterile conditions, it was very difficult to place the tulle separator well on petri dish 2 and the tulle melted due to the heat of the Bunsen. It did not stick uniformly on the dish. Tulle separator from petri dish 4 was also not sticking to the substrate in some spots. All the petri dishes were inocultated with fresh Reishi mycelium grown previously on malt agar. The strain was kindly provided by Jessica Dias. Dishes were put to grow in dark, moist 25°C environment.
Image: Petri dishes on day 1.
Results
Table: Pictures of the different petri dishes on day 1, day 9 and day 20. Only the first two petri dishes on malt agar grew. The rest of the experiments got covered with a white pelicula after some days, indicating contamination.
Conclusion
Considering the very dissapointing results of this experiment, I decided to pay more attention to sterilization steps for further experiments. Given the nature of the substrate (food waste), 90 minutes pressure cooking sterilization (minimum) will be applied for the further experiments. Additionaly, fresh food waste will be prioritized over dried food waste when possible. The separator experiments showed on the controls that mycelium would grow more or less equally if a separator with adequate width pores is positionned on top of the substrate.
Second attempt (10/02/2022)¶
Image: Petri dishes from the second attempt experiment.
Considering the unsuccessful first experiments I had with Reishi, I decided to continue testing the growth of the mycelium of Reishi and Oyster using fresh food waste and textile, and taking the separator parameter off.
For this second wave of experiments, denim textile waste and fresh food waste was used to make sure the results of the first experiments were not an artefact. During the previous experiments, I had to face a lot of contamination problems due to the nature of the substrates (waste). I thus made sure to sterilize all my glassware and mediums for at least 90 mins to avoid this problem. In these experiments, different types of waste were used. Synthetic and denim textile waste were provided by Fab Lab Barcelona, issued from textile scraps. Food waste was obtained by recycling vegetable peels (carrots, cucumbers, onions, celery, broccoli) I used for my personal consumption. Coffee grounds waste were also obtained from my personal consumption of sachets from the brand Marcilla.
| Waste | Preparation |
|---|---|
| Mixed food waste | Fresh food waste was collected and blended using a hand food blender. Food waste was not dried before experiments. Humidity level was adjusted using approximately 50 mL water for 50g of food waste. |
| Synthetic textile waste | Synthetic textile waste was collected, humidified with a ratio of 50 mL of water for 50 g of textile and blended using a hand food blender. |
| Denim textile waste | Denim textile waste was collected, humidified with a ratio of 50 mL of water for 50 g of textile and blended using a hand food blender. Even when the textile was new (textiles scraps), the denim was not washed prior to experiments. |
| Wheat grain | Wheat grain was prepared according to the spawn preparation protocol, that is to say soaking organic wheat grain in tap water overnight, half cooking it for 25 minutes and letting the surface water dry by straining it overnight. |
| Coffee grounds | Coffee grounds were obtained by cutting open used coffee sachets for coffee machines and drying them. |
Table: preparation of the different types of wastes. ALL THE SUBSTRATES MENTIONNED AFTER THIS TABLE WERE PREPARED AS DESCRIBED IN THIS TABLE. For instance, if a table mentions "denim textile waste" it actually means shredded, humidified non washed denim textile waste.
Image: wastes used during the project (from left to right: food waste, denim textile waste, coffe grounds, synthetic textile waste and gain).
Once put in the petri dishes, all the samples were pressure cooked for 2,5 hours to avoid any kind of contaminations and then inoculated with 1 cm² of G. lucidum or 1 cm² of P. ostreatus grown on agar. For more accurate interpretation of the results, all the experiments were carried out in duplicates.
Ganoderma lucidum (Reishi)¶
Image: Image: Reishi mushroom, from GroCycle.
| Denim textile waste and fresh food waste | Denim textile waste and wheat grain |
|---|---|
| 30 g denim textile waste, 70 g mixed domestic food waste and 5 g coffee grounds | 30 g denim textile waste, 90 g half cooked wheat grain and 5 g coffee grounds |
Table: Substrate mixes tested with G. lucidum mycelium.
Petri dishes were taped with parafilm and incubated to grow in a 27° (± 4°C) incubator.
Denim textile waste and fresh food waste
Table: Reishi mycelium growing on denim textile waste and fresh food waste. Reishi did not grow on the denim textile waste and fresh food waste mix.
Denim textile waste and wheat grain
Reishi mycelium denim textile waste and wheat grain. Reishi grew very weak on the denim textile waste and wheat grain mix.
Pleurotus ostreatus (Oyster)¶
Image: Oyster mushrooms, from GroCycle.
Since the first Reishi experiments were unsuccessful, I launched the Oyster experiments at the same time I launched the second wave of Reishi experiments.
The same raw materials as the ones described in the previous paragraph were used as substrates. Once put in the petri dishes, all the samples were pressure cooked for 2,5 hours to avoid any kind of contaminations and then inoculated with 1 cm² of P. ostreatus (Oyster) mycelium grown on agar.
The experiments are separated in 3 sections for better understanging: the controls, the mixes containing denim textile waste and the mixes containing synthetic textile.
Controls¶
| Waste | Mix preparation |
|---|---|
| Coffee grounds | Coffe grounds only |
| Denim textile waste | Denim textile only |
| Synthetic textile waste | Synthetic textile only |
Table: Control petri dishes tested with P. ostreatus (Oyster) mycelium.
Oyster mushroom mycelium on coffee grounds. Oyster mycelium grew on coffee.
Oyster mushroom mycelium on denim textile waste. Oyster mycelium grew weak on denim.
Oyster mushroom mycelium on synthetic textile waste. Oyster mycelium did not grow on synthetic textile.
Denim textile assays¶
| Waste | Mix preparation |
|---|---|
| Denim textile waste and coffee grounds | 30 g denim textile waste, 10g coffee grounds |
| Denim textile waste and fresh food waste | 30 g denim textile waste, 90 g half cooked wheat grain and 5 g coffee grounds |
| Denim textile waste and wheat grain | 30 g denim textile waste, 70 g mixed domestic food waste and 5 g coffee grounds |
Table: Substrate mixes tested with P. ostreatus (Oyster) mycelium incorporating denim textile.
Denim textile waste and coffee grounds. Oyster mycelium grew strong on the mix.
Denim textile waste, fresh food waste and coffee. Oyster mycelium grew strong on the mix, fully colonizing the dish.
Denim textile waste, wheat grain and coffee. Oyster mycelium grew very strong on the mix.
Synthetic textile assays¶
| Waste | Mix preparation |
|---|---|
| Synthetic textile waste and fresh food waste | 30 g synthetic textile waste, 70 g mixed domestic food waste and 5 g coffee grounds |
| Synthetic textile waste and coffee grounds | 60 g synthetic textile waste and 5 g coffee grounds |
Table: Substrate mixes tested with P. ostreatus (Oyster) mycelium incorporating synthetic textile.
Synthetic textile waste, fresh food waste and coffee. Oyster mycelium grew weak on the mix.
Synthetic textile waste and coffee grounds. Oyster mycelium grew very weak on the mix.
Conclusions¶
- G. lucidum (Reishi)
This second wave of experiments did not lead to good growth of the Reishi mycelium. However, sterilization for at least 90min led to the absence of contamination of the petri dishes. The lack of growth can be due to the textile waste not being a possible substrate for the Reishi mycelium (or even toxic to its growth), but can also be due to the fact that the mother Reishi mycelium used for inoculation was a bit old and had continuously been replated for around 3 month (for more information on this matter, check Spawn growth for strong mycelium tab). In order to know for sure, the same experiment should be carried out using a colonized wheat grain (from the Reishi mycelium spawn) for inoculation instead of a 1 cm² chunk of mycelium grown on agar. This experiment was not carried out due to lack of time and considering that the Reishi spawn was not ready yet back then.
- P. ostreatus (Oyster)
Oyster mycelium gave much more interesting results than Reishi mushroom mycelium. The results on denim textile waste are very promising, as it grew strong on this textile mixed with additives (food and coffee wastes) and even grew weak on denim textile waste only ! The oyster mycelium also did not die when exposed to synthetic textile waste showing it is not toxic to its growth, even though it could not developp from it alone. These result give good and immediate perspectives for the developpement of a composite mycelium leather combining textile waste and mycelium. Another perspective on a longer term is the training of this strain to degrade the textile waste of both kind more efficiently.
Qualitative chart of the substrate experiments results.
Midterm presentation¶
Here is my midterm presentation, featuring the work I made during the first 7 weeks of research of my final project and the directions I wanted to take it to.
Mid Term presentation Fabricademy par Sangosanya Annah-Ololade
Image: midterm presentation samples.