FUNGUY

https://youtu.be/A6M-sxuNi24

https://github.com/b-w-wilson/Funguy_GUMS

Growing food in conditions of microgravity has been a matter of interest for the scientific community for a long time, mainly because our dream to conquer outer space can only be accomplished if the basic human needs are satisfied.

Pleurotus ostreatus and its mycological characteristics

Currently, there are at least 12,000 species of mushrooms worldwide out of which 2,000 species are reported as edible and only 35 are commercially cultivated, with Agaricus bisporus being the most popular. In this project, we have decided to cultivate Pleurotus ostreatus by considering the time of growth and the availability of mycelium on the market. Known as oyster mushroom, Pleurotus ostreatus is a common saprophyte species of the basidiomycetes group, one of the two main large divisions which form the subkingdom Dikarya within the fungi kingdom. As the name suggests, the species has an offset, tongue-, spatula-, or oyster-shaped pileus spanning 2-30 cm. The colour of the pileus can vary between different shades of grey. The pileus is supported by a short, whitish, eccentric or lateral stripe, and, therefore, its thickness depends on the stripe arrangement. White or cream lamellae occur on the decurrent hymenium whereas the white to lilac-grey spore print shows 8-12 μm ⨯3-4 μm sized, hyaline spores. 

In the natural environment, Pleurotus ostreatus thrives on the living or dead parts of plants in temperate and subtropical forests during autumn and winter times, when the temperatures are up to 15℃. High carbon dioxide concentrations, up to 28% of the volume, stimulate the growth. 

Mushrooms as an ideal source of nutrients

Either on Earth or in space, a balanced nutrition is crucial in providing the organisms the necessary minerals to maintain high energy levels and, subsequently, good health. 

Since antiquity, the fructification of higher fungi has been an integral part of the human diet as it is easily seen with the naked eye, picked by hand, and consumable without processing. The reason for which mushrooms are appearing more and more frequently on our plates is because they represent are source of variety of nutraceutical compounds such as polysaccharides (β-glucans), dietary fibres, terpenes, peptides, glycoproteins, alcohols, mineral elements, unsaturated fatty acids, antioxidants like phenolic compounds, tocopherols, and ascorbic acid. Moreover, the bioactive compounds have proven effects on strengthening the immune system and prevention of heart diseases, hypertension, cerebral stroke and cancers. Mushrooms are also known to exhibit antifungal, anti inflammatory, antitumor, antiviral, antibacterial, hepatoprotective, anti-diabetic, hypolipedemic, antithrombotic and hypotensive activities. Depending on the species, varieties, and the stage of development of the fruiting body, the crude protein content of edible mushrooms ranges from 10% to 35% of dry weight (DW). The dry weight recommended to maintain an optimal nutritional balance in a man weighing 70 kg is 100- 200 g. 

Mushrooms are richer in proteins than most vegetables. Specifically, the amount of essential amino acids in mushroom proteins ranges from 30 to 50g/100g protein DW, from which the most important ones are glutamic acid (130–240 mg/g protein DW%), aspartic acid (91–120 mg/g protein DW %) and arginine (37–140 mg/g protein DW%). Besides these, the two unusual amino acids γ-amino butyric acid (GABA), a non- essential amino acid, and ornithine, known for their peculiar physiological activities, have also been found. Similar to proteins, the carbohydrate content in the fruiting bodies comprising of monosaccharides (eg sugars), oligosaccharides (eg trehalose and non-starch polysaccharides), and small amounts of sugar alcohol, such as mannitol and trehalose serve as 50 to 65% on dry weight. 

In comparison with carbohydrates and proteins, mushrooms are low in lipids (less than 5% DW). With a total lipid content of 20 to 30 g kg-1 DM, mushrooms contain unsaturated fatty acids, such as linoleic and oleic acids and tocopherol. Whereas tocopherol is an important antioxidant, the linoleic acid has been mentioned to exhibit anti-carcinogenic effects on almost all stages of tumorigenesis in breast, prostate, and colon cancers. The vitamin content of five types of mushrooms are presented in Table 1. 

Figure available in document in Final Project.

Fig 1: The concentration of vitamins in five species of commercial mushrooms (Afiukwa, Celestine & P.C., Ugwu & Okoli, S.O. & Idenyi, John & Ossai, Emmanuel. (2013). Contents of some vitamins in five edible mushroom varieties consumed in abakaliki metropolis, Nigeria. Research Journal of Pharmaceutical, Biological and Chemical Sciences. 4. 805-812.)

Besides the vitamins mentioned in the table, mushrooms represent a good reservoir of vitamins B and D. When exposed to UV light, fungal sterol, ergosterol, is converted to vitamin D2 through a series of photochemical and thermal reactions, in amounts greatly higher than that of daily requirements. 

Cultivation of mushrooms: between science and art 

As we have shown in the previous section, mushrooms provide a large variety of nutrients necessary for the good functioning of the human body. Besides their obvious multi-functional medical properties, the fast growing period and the capacity to thrive in spatially-restricted areas may make the spore- bearing fruiting body of fungus the ideal consumable entirely grown on a spaceship. 

Annually, the mushroom cultivation market is estimated to be $16.65 billion in 2020 and is expected to reach $22.78 billion by 2028. The popularity of the commercial species, including Pleurotus ostreatus, is attributed to the rapid growing rates, being ready for harvest after 7 days. Moreover, in a controlled environment, due to its high saprophytic colonisation ability, the entire cultivation is more straightforward as the substratum is fastly penetrated. 

Environmental conditions 

In comparison with the natural requirements, the commercially-produced mycelium should benefit from higher optimal air temperatures. As noticed in the graph, the acceleration of growth occurs between 15 and 20 ℃. 

Figure available in document in Final Project.

Figure 2: The mycelium growth as a function of temperature (ZADRAŽIL, F., 1978. Cultivation of pleurotus. The Biology and Cultivation of Edible Mushrooms, pp.521–557)

Another reason for which agriculture focuses on the Pleurotus group is that the mushrooms can flourish on artificial substrate on synthetic materials as long as it is associated with the corresponding nutrient solution. The table below shows the concentrations of the nutrients necessary to support mycelium development.

Figure available in document in Final Project.

Fig 3: Nutrients and correspondent concentrations for mycelium growth (Prof. Chandra Madramootoo, “Mycelium and Mushroom Production Using a Hydroponic Porous Tube Nutrient Delivery System”, Department of Bioresource Engineering, McGill University, Macdonald Campus, April 2018)

Regarding the amount of oxygen, discussion is more complex considering that the development stages differ in oxygen requirements: mycelial growth demands semianaerobic conditions whereas carpophores develop under the presence of oxygen.

Figure available in document in Final Project.

Fig 4: The mycelium growth as a function of oxygen concentration (ZADRAŽIL, F., 1978. Cultivation of pleurotus. The Biology and Cultivation of Edible Mushrooms, pp.521–557)

PH is another parameter which should be taken into account when cultivating mushrooms as acid (pH= 4) and basic (pH= 7) settings inhibit the growth. However, considering that the mycelium growth lowers the pH values quickly, slightly higher values than the optimum can also be accepted as well.

Growing mushrooms in space 

GUMS: Growth Unit for Mushrooms in Space is an ingenious mushroom growing hybrid system idea consisting of an electromagnetically treated homogeniser for nutrient mixing and solution sanitising and hydroponic porous ceramic tubes for the nutrient delivery and recycling. The growing environment will be wirelessly monitored via an autonomous sensor system, which transmits the air sensing (air temperature, relative humidity, atmospheric gases concentration, light intensity) and water sensing (solution temperature, pH, electrical conductivity, concentration of oxygen and nutrients) data to a mobile app. Further improvements would include a treatment and dehydration stations.

Our GUMS design has been inspired by NASA’s PTPNDS system. In 2003, T.W. Draschel has published in NASA Technical Memorandum the technical design of a device which utilises a loop to control the delivery of water and nutrients to the roots of super-dwarf wheat and, subsequently, to prevent the anoxic effects experienced by plant rhizospheres in conditions of microgravity. According to the paper, eight porous ceramic tubes with a diameter of 2 cm and 80 cm length are connected to a magnetically coupled impeller at the upstream end and to a peristaltic pipe at the downstream end. These tubes are fed by a 80 litres nutrient tank attached to the upstream end whereas the solution is removed out of the system and recycled at the downstream end. Metal-halide lamps provide the necessary active radiation for photosynthesis and a bracket system is attached to diffuse the liquid nutrient solution under pressure.

Figure available in document in Final Project.

Fig 5: Scheme of Porous Tube Plant Nutrient Delivery System (T.W. Draschel, “DEMONSTRATION OF A POROUS TUBE HYDROPONIC SYSTEM TO CONTROL PLANT MOISTURE AND GROWTH”, NASA Technical Memorandum 2004-21 1533, October 2003)

The outline of the system is further developed by the Department of Bioresource Engineering of McGill University, Canada, in order to make it functional for mycelium and mushroom production. GUMS is a modified version of this model which uses an alignment of three porous ceramic tubes, each of 15 mm in outer diameter, 10 mm in inner diameter and 200 mm in length, rather than only one, making the system more suitable for much smaller space. If the growing chamber of McGill University’s porous tube plant for nutrient delivery system needs a 1.09 m in length, 0.59 m in width and 0.52 m in length container for the assembly, GUMS only uses 60 cm in length, 35 cm in width and 40 cm in height. Due to the reduced dimensions of the container, GUMS require less energy to be humidified and heated up, which means that we also save energy, and, therefore, money. Besides the continuous monitoring of multiple environmental parameters amongst which some uncommon ones, such as light intensity, pH and electrical conductivity, GUMS makes use of the newest discoveries in the full solution sterilizing treatments to prevent the contamination noticed in McGill University’s system and, subsequently, the pump clogging.

Figure available in document in Final Project.

Figure 6: Nutrient Delivery System seen from above (Prof. Chandra Madramootoo, “Mycelium and Mushroom Production Using a Hydroponic Porous Tube Nutrient Delivery System”, Department of Bioresource Engineering, McGill University, Macdonald Campus, April 2018)

Figure available in document in Final Project.

Figure 7: Nutrient Delivery System seen from above (GUMS design)

Nutrient delivery system

An inert substrate of organic brown rice flour, vermiculite and gypsum was sterilized and inoculated with a liquid media containing Pleurotus ostreatus spores. The axenic nutrient solution is dispersed into a bed of nutrient free substrate, encased by ABS pipes around the ceramic tubes. The ceramic tubes are, then, joined to a 5L nutrient tank by opaque, PVC pipes. The opacity of the pipes diminish the chances of internal algal contamination. In the nutrient tank, we added a centrifugal submersible pump, attached to the nutrient tank walls using silicon caps. The remaining solution which circulated through the system is transported downstream to the nutrient tank where the consumed nutrients are replenished. 

Nutrient mixing and treatment station

From (Prof. Chandra Madramootoo et al., April 2018), we know that contamination of nutrient and water solution may be an issue, especially during the mixing. From this, we propose a system may be to mix the water and nutrient solution inside a sealed mixing chamber. This will allow for the inlet of nutrients at high pressure to mix directly with the water, creating an even distribution of components. 

The homogenization will occur in a venturi space, where mechanical mixers are placed. The surface of the venturi chamber is circularly-ridged to promote further physical and chemical reactions in the aqueous media. The inlets to the chamber of the mixer as well as the nutrient tank include a jacket insulation to keep the temperatures of the liquid solutions below room temperature, and, subsequently, to increase the dissolution of oxygen and nitrogen.

In comparison with other subsystems, the venturi chamber should be treated with maximum care as there are high chances for contamination, despite UV sterilising the water before connecting to the inlet. The risk of contamination can be drastically reduced by utilising EMF solution treatment. EMF has been widely used for centuries to mitigate bacterial contamination, but also to assist the electrocoagulation and advanced oxidation processes. In comparison with electrolysis for which the presence of electrodes in the nutrient solution tank is mandatory, in the EMF treatment technique, solenoid coils are attached in the proximity of the venturi chamber to induce an electromagnetic field of high intensity and less homogeneous waveform in the liquid. Moreover, as electrodes need to be frequently checked and periodically changed, electrolysis is associated with high maintenance cost, which cannot be said about our treatment unit. 

Growth chamber 

The growing chamber is our own customised polycarbonate bin, supported on a wooden base, measuring 60cm in length, 35cm in width and 40cm in height. We included the ceramic tubes inside the bin whereas the nutrient mixing and treatment station is kept outside the bin. The openings cut in the polycarbonate sheets to connect the subsystems have been surrounded by flexible silicone adhesive in order to forbid the air flow transfer between the bin and the outer space. The stability of the ceramic tubes is given by plastic fittings. The whole chamber is surrounded in 40mm PIR insulation to trap heat and moisture inside and reduce the energy requirements of the system.

System Walkthrough

https://b-w-wilson.com/Walkthrough_edit.mp4

CAD

https://github.com/b-w-wilson/Funguy_GUMS/tree/main/CAD

System architecture and state machine diagrams

https://github.com/b-w-wilson/Funguy_GUMS/tree/main/Diagrams

Heating system 

The heating system comprises a 2L soda bottle, partially filled with water in which an aquarium heater is glued with silicone adhesive. The heater has incorporated a thermostat so as we are able to change the temperature to accommodate different growing stages. Currently, as our system is in the mycelial growth stage, we keep the temperature higher, at 25 degrees Celsius and the humidity at 85%. 

Wireless environmental monitoring 

To monitor the environment around our system, alongside the environment inside our system, we propose that a series of sensors could be used to monitor all aspects of the fungi growth. This system would be controlled by a central computer, which would receive many inputs from sensors, and output the calculated result to the actuators.

The air parameters FUNGUY decided to monitor are air temperature, relative humidity, atmospheric gases concentration, light intensity. The light is provided by a 4.5W 2700K LED bulb. The state of the nutrient solution is communicated by water sensors, such as the solution temperature, pH, electrical conductivity, and concentration of oxygen and nutrients. 

These sensors should be wireless, enabling a clean wire-free connection from inside each individual growth chamber, to the main monitoring computer. Alongside this, the actuators would also be wireless. These actuators would be pump output, humidifier output, heater output, and LED bulb output.

Modular design

GUMS has been designed to sit on two rails and be rack mounted. At the back of the bin there is a input/output port, allowing for power inside the chamber alongside nutrient solution to be filled. If for any reason a GUMS unit fails, it can be quickly swapped out with a functional unit to ensure that enough food is continuously being grown onboard the craft. A system failure would automatically be noticed by the wireless environment monitoring, and personnel would be notified via the mobile app that a unit has malfunctioned.

Our GUMS design has been inspired by NASA’s PTPNDS system. Between 1992 and 2003, T.W. Draschel has published in NASA Technical Memorandum the technical design of a device which utilises a loop to control the delivery of water and nutrients to the roots of super-dwarf wheat and, subsequently, to prevent the anoxic effects experienced by plant rhizospheres in conditions of microgravity. According to the paper, eight porous ceramic tubes with a diameter of 2 cm and 80 cm length are connected to a magnetically coupled impeller at the upstream end and to a peristaltic pipe at the downstream end. These tubes are fed by a 80 litres nutrient tank attached to the upstream end whereas the solution is removed out of the system and recycled at the downstream end. Metal-halide lamps provide the necessary active radiation for photosynthesis and a bracket system is attached to diffuse the liquid nutrient solution under pressure.

Overall, Space Apps Challenge has been a unique experience in which we have had the opportunity to grow both personally and professionally!

Over the weekend and the month prior to the challenge, we have planned out as much as possible our GUMS system and have tried to get a basic mycology background in order to better understand how mushroom growth in hydroponics based systems. We are looking forward to continuing the development by adding the additional subsystems to the main porous tube nutrient delivery system. We believe that the solution we have came up with will certainly make a difference not only in long distance space travel, but also on Earth.

Overall development of the project started with planning stage. We started with initially coming up with a few ideas of projects that we could work on, and after brainstorming some ideas around hydroponics and tomato/lettuce growth, ordered pizza. Rebeca ordered a pizza with mushrooms on it, to which Bruce responded by voicing his dislike for mushrooms. Rebeca asked what Bruce would do if he was stuck somewhere and all there were to eat were mushrooms, to which Bruce responded, “hmm.. well we could use our hydroponic system to grow mushrooms”, and there we are. With the decision made, we spent a few weeks doing background research, ensuring that on the weekend of the hackathon, we could put together our report, and build the system from scratch. Alongside this, we placed any orders of hardware or parts that they would arrive for the weekend.

On the weekend of the hackathon, we started bright and early at 9am beginning the build. First creating the growth tubes (connector ends, black ABS tube, ceramic tube), then connecting them together to the pump and nutrient tank. With a quick trip to B&Q to pick up some extra sealant and pipe 90 degree turns, this system was mostly complete, with a few worries about leaks due to how quickly it had been put together. Then on day two, the wooden base was built, along with finishing touches to the tube system. The polycarbonate encasement alongside PIR insulation was then constructed around the box, ensuring that all gaps were sealed shut with aluminium tape. Nearing the end of day two, we recorded the walkthroughs and turning on of the pump for the first time.

Our biggest challenge was faced with the heating element. Our original plan called for a 2L cola bottle to be cut and an aquarium heater placed inside, however it proved too difficult to seal once it had been opened. With some other attempts with plastic bags, cut parts of a tube, and a trip to Tesco to quickly by a cereal container in a last-ditch attempt. Unfortunately we were unable to get the heater working and in a safe, sealed environment by the end of the hackathon. Alongside this, our fears were met with reality with a few small leaks from the tubes upon the pump being ran for a few minutes. We will drain the system and fix the leaks with epoxy.

Overall, we were very content with what we have been capable to build, considering how quickly it was manufactured. It was greatly aided by the 3D printed pipe connectors and fast drying epoxy/solvent cement. While we have bought the substrate and mushroom spores in a syringe, we have yet to put the substrate in the tubes. This was due to the leaks appearing and lack of time near the end of the weekend. We fully intend on still attempting to use the system in the coming weeks.

Photo Gallery of GUMS system built during NASA Space App Challenge

https://github.com/b-w-wilson/Funguy_GUMS/tree/main/Build

Walkthrough

https://b-w-wilson.com/Walkthrough_edit.mp4

CAD

https://github.com/b-w-wilson/Funguy_GUMS/tree/main/CAD

System architecture and state machine diagrams

https://github.com/b-w-wilson/Funguy_GUMS/tree/main/Diagrams

Twitter

@FUNGUY_NSAC

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2. Dreschel, T.W., Brown, C.S. & Piatstuch, W.C., A summary of porous tube plant nutrient delivery ... - NASA. Available at: https://ntrs.nasa.gov/api/citations/19920018634/downloads/19920018634.pdf?attachment=true [Accessed October 3, 2021]. 
3. Madramootoo, C., 2018. Mycelium and mushroom production using a hydroponic porous tube nutrient delivery system. eScholarship@McGill. Available at: https://escholarship.mcgill.ca/concern/reports/ws859m033 [Accessed October 3, 2021]. 
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7. Jiang, W. et al., 2019. A pilot study of an electromagnetic field for control of reverse osmosis membrane fouling and scaling during brackish groundwater desalination. Water, 11(5), p.1015. 
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12. Woodland Trust, Oyster Mushroom. Woodland Trust. Available at: https://www.woodlandtrust.org.uk/trees-woods-and-wildlife/fungi-and-lichens/oyster-mushroom/ [Accessed October 3, 2021]. 
13. Anon, 2021. Pleurotus ostreatus. Wikipedia. Available at: https://en.wikipedia.org/wiki/Pleurotus_ostreatus [Accessed October 3, 2021]. 
14. Sayner, A., 2021. How to grow oyster mushrooms: The ultimate step by step guide. GroCycle. Available at: https://grocycle.com/how-to-grow-oyster-mushrooms/ [Accessed October 3, 2021]. 
15. Ting Chang , S. & Wasser, S.P., 2017. The Cultivation and Environmental Impact of Mushrooms. Oxford Research Encyclopedias, Environmental Science. 
16. Chang, S.-T., 1991. The biology and cultivation of edible mushrooms, San Diego: Academic Press. 

Tools:

1. Wix.com: Free Website Builder
2. Adobe Illustrator
3. Adobe Photoshop
4. CAD, CAM Fusion 360

#hardware #data #mushrooms #growth #PTPNDS #hydroponics

This project has been submitted for consideration during the Judging process.