Mushrooms are a well-known nutritious source consumed by many people all over the world. They are basically fungi, which require entirely different conditions to grow, when compared to plants. Although due to their edible nature, few people call mushrooms plants, and they are not from the Plantae kingdom.
Mushrooms are heterotrophs, which means they survive on food sources from their surroundings. The environment provides them with nutrients; For eg., plant matter, animal waste and organic carbon. The cell walls of mushrooms differ exponentially from their plant relatives. The cell wall of mushrooms is produced from complex polysaccharides, glucan and chitin. These cell walls protect mushrooms from predators and improve structural integrity. So how do they grow and what are the conditions required?
Mushrooms emerge from fungal spores that survive in damp, dark conditions. They need a medium that is high in decaying plant matter. They often spring from dead trees. Commonly, mushrooms are artificially grown inside large plastic bags, filled with sterilised sawdust and wood chips.
The growing cycle is usually six weeks. The first three weeks are used for growing the vegetative part of the fungus, called the mycelium, which is similar to roots of a plant. This process is also called colonising the casing layer. In the last three weeks, mushrooms are picked and grown again.
After the first three weeks, the temperature in the growing room is dropped below 20 degrees Celsius. This temperature is a gesture for the fungi to develop the fruit body, and drop the spores that are present in the gills underneath the mushroom cap. This is a process of tricking the mushrooms into growing fruit bodies all-round the year.
Mushrooms can be grown in an agar filled petri dish too. First, mushroom spores are placed on a nutrient-rich media. This has to be conducted in a clean environment, to ensure that bacteria and molds do not land on the petri dish. Next, a small sample of mycelium can be cut and transferred to a jar of sterilised grain.
The mushroom mycelium will eventually grow out, encapsulating the grain. The bits of grain (called spawn) can be utilised to inoculate other sterilised grain jars. Similarly, one jar can be used to spawn 10 more jars. Once you collect enough grain spawn, it can be used to immunise a layer for growing mushrooms. Usually this includes straw, wood chips or compost.
The mushroom mycelium will continue to expand, consuming these nutrients and immersing the substrate. Once it is entirely immersed, the process of pinning starts. By changing the temperature as per requirement, the mycelium will start to form little knots, eventually turning into pins. These pins will continue to grow, forming full mushrooms.
You might have seen mushrooms sprout from many places. Ever wondered why they grow so easily? This is because mushrooms are decomposers, meaning they break down organic matter for nutrients. This makes them grow in a variety of environments. They also use spores for reproduction, instead of seeds. This microscopic substance travels easily through air, and colonises new areas with ease. Besides, the maintenance of mushrooms is minimal. All they need is moisture, oxygen and organic matter.
Mushrooms can be grown in space too! NASA conducted experiments on how to grow fungi in environments without gravity. In 2015, astronauts on the International Space Station cultivated Lentinula Edodes mushrooms. Another fascinating revelation is that mushrooms exhibit characteristics of bioluminescence, meaning that they glow in the dark! This is because of the same compounds present in them, akin to fireflies, which is luciferin and luciferase.