Are mushrooms autotrophic or heterotrophic? It is often quite confusing for people to answer this because they do not know whether mushrooms produce their own food or not.
It is clear that only autotrophs can produce their own food like plants, which use sunlight to produce their food through photosynthesis.
Now, you may think that because mushrooms look like a type of plant, they must be autotrophic organisms.
So, are mushrooms autotrophs or not?
Mushrooms are considered heterotrophic because they have to rely on other organisms to obtain food and nutrients.
Understanding More About Mushrooms
Mycologists, the experts who know their mushrooms, believe there could be well over 14000 kinds of mushrooms with many to discover.
However, mushrooms can be classified into four distinct species:
- Saprotrophic
- Mycorrhizal
- Parasitic
- and Endophytic
Where each mushroom is grouped according to how it feeds, such as:
- The saprotrophic feed on decaying matter.
- Mycorrhizal fungi feed off trees and plant roots underground.
- The parasitic feed off plants and trees to eventually kill them.
There are also different examples of these mushrooms.
For instance, the most common types of saprotrophic mushrooms are:
- Shiitake
- White button
- Oyster
- Puffballs
Similarly, some of the most common types of mycorrhizal fungi include:
- Truffles
- Matsutake
- Caesar’s mushrooms
Fact: Fungal spores are the germinating point for mushrooms, which is also where mushroom farmers begin cultivating these savory treats.
The Concept of Mushrooms and Fungi
Mushrooms belong to a diverse group called fungi. Many fungi look plant-like, although they are not.
Fungi and mushrooms reproduce by dispersing spores not by seed, as plants do.
As diverse as they are, mushrooms are present in some form in almost every ecosystem on earth.
In healthy systems, they are a large part of the soil diversity and are active in nutrient and carbon recycling.
In huge underground networks, they transform complex decaying plant matter into simpler forms they can feed on and the vegetation around them can use.
This includes carbon.
Mushrooms help shift carbon out of the decaying matter, into the vegetation and out as CO2 into the atmosphere.
An Important Consideration
Mushrooms also store carbon themselves in times of stress, using to strengthen cell walls, effectively locking it away for years.
One study revealed that biodiverse soil could capture up to 10 tonnes of carbon per hectare per year.
Fact: Many types of mushrooms require different levels of humidity, heat, and air flow in order to thrive.
Are Mushrooms Autotrophic or Heterotrophic?
All organisms can be classified as heterotrophic or autotrophic depending on how they get their energy.
And to understand where mushrooms fit, it is important to learn more about these two categories.
Heterotrophic Organisms
A heterotrophic organism is a consumer occupying the second and third levels in the food chain.
Some common examples include the ruminating herbivores as well as ourselves.
Autotrophic Organisms
Autotrophic organisms manufacture their own food and, as such, are producers occupying the first trophic level, with cabbage, grass, algae and anything green being examples.
Autotrophs feed by converting inorganic carbon dioxide (CO2) into carbohydrates and other organic compounds, usually by the process of photosynthesis.
So, is a mushroom an autotroph?
Well, mushrooms occupy the second trophic level feeding on organic matter and so are heterotrophic.
Why are Mushrooms not Autotrophic?
Unlike green plants, mushrooms do not use any kind of pigment to photosynthesize.
It is mainly due to the fact that they lack chlorophyll, the green of green plants, and have no way to produce it.
The Role of Chlorophyll in Autotrophs
In green plants, the compound of chemicals known as chlorophyll is found in the membrane of a cell structure called the chloroplast.
This is the cell responsible for photosynthesis and for storing the sugars that result.
Mushrooms cells lack this structure or anything with a similar function.
Instead, mushrooms, like all fungi, feed through absorption using specialized enzymes they secrete directly onto and around the substrate.
The Effect of Light on Heterotrophic Mushrooms
The chloroplast is a highly specialized organic molecule that absorbs the high blue wavelengths of light for use in the process of photosynthesis.
The low wavelengths are reflected away and we see them as green.
The plant needs light to stay green and healthy. On the other hand, mushrooms prefer the dark.
With no way to photosynthesize, they have no need for light but will thrive in dark humid warmth.
They work by spreading out a mat of fine threadlike tendrils forming an expansive root structure called the mycelium.
It anchors and supports the mushrooms and collects the food, water and nutrients it needs.
Mechanisms Used by Mushrooms to Obtain Nutrients
In order to understand how heterotrophic mushrooms get nutrients, you have to understand the role of their root structure, called the mycelium.
The mycelium forms a cobweb of fine white strands called hyphae.
They produce lytic enzymes that break down the decay matter’s chemical compounds into their simplest usable form.
The mushroom absorbs all sugars and proteins it needs through the hyphae as it spreads out to digest its way through the substrate.
The Working Mechanism of Mycelium
In areas with good soil diversity the mycelium within is a rich network of hyphae that intertwines and covers everything dead, dying or decaying.
Underground, most of it remains unseen even though in some places such as the rainforest, the mycelium could be spread out through the soil as one single entity for many, many miles.
Some types of mycelia are visible. They form molds in damp places.
Research is ongoing into how different mycelium could be useful, it is particularly absorbent, but all experts agree that mycelium is vital for the health of an ecosystem.
Mushrooms and other Heterotrophic Organisms
All heterotrophic organisms need a reliable supply of suitable nutrients that must be provided by an external source.
Humans for example, have adapted their environment to favor themselves as consumers.
We raise livestock and mass plant crops such as wheat, corn and oil palm.
The carnivores and omnivores make up the heterotrophic organisms although not all have the same impact on their environment.
The Case of Heterotrophic Mushrooms
Speaking of mushrooms, hyphae are referred to as the building blocks of mycelium.
And each has the same function as the mycelium, to use the environment to supply the mushroom with nutrients.
Although mycelium spreads widely, unlike man, it is immobile and incapable of controlling its environment as other heterotrophic organisms do.
Being immobile restricts how an organism can feed, unlike the herbivores, who can move on to better grazing with the carnivores following them.
Fact: Mushrooms should be kept in a clean brown paper bag to allow for enough air circulation or they will rot quickly.
The Benefits of Heterotrophic Nutrition in Mushrooms
Immobility tends to be a characteristic of organisms with chlorophyll that photosynthesize their food. However, fungi are a versatile group.
Fungi can breakdown and make use of a wide range of organic compounds including:
- Nitrates
- Ethanol
- Ammonium acetate
They do it with their tubercular finger-like cells of hyphae facilitating an efficient movement of nutrients through the mycelium to the mushroom.
Nutrition in Mushrooms
Mushrooms have digestive enzymes, called exoenzymes because they work outside the organism.
Because of these digestive enzymes, they are capable of digesting even large molecules, such as those of polysaccharides, lipids and proteins, adding further to their level of feeding efficiency.
An Important Consideration
Global climate change has prompted scientists to seriously consider how fungi can improve soil quality on a large scale.
Both fungi and plants are involved in soil carbon sequestration.
Mycelium may have a role in storing carbon in slow decaying matter, delaying its release into the atmosphere as harmful carbon dioxide.
Fact: Certain types of mushrooms produce a considerable amount of vitamin D2 when exposed to UV light, either from the sun or a UV lamp.
Takeaway
Are mushrooms autotrophic or heterotrophic? Mushrooms belong to a larger group of organisms known as fungi.
And though some fungi are autotrophs, it is not the case with mushrooms.
In order to sustain themselves, mushrooms feed off of dead or decaying organic matter produced by other creatures, a process known as heterotrophy.
Mushrooms, which are decomposers, get the nutrients they need by reducing complex molecules found in decomposing matter (such as dead plants and animals) to smaller ones.
