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Environmental Microbiology

Decomposers – Definition, Mechanisms, Types, Example

What are Decomposers? Decomposers are the creatures that carry out the process of decay or breakdown of a dead organism, while decomposition...

Decomposers - Definition, Mechanisms, Types, Example
Decomposers - Definition, Mechanisms, Types, Example

What are Decomposers?

  • Decomposers are the creatures that carry out the process of decay or breakdown of a dead organism, while decomposition is the process of breaking down complex organic matter into its simpler form.
  • In environmental science and ecology, decomposers are the organisms involved in the decomposition of animal and plant debris in an ecosystem.
  • Bacteria and fungi are the primary decomposers in an ecosystem. One might ask what these decomposers consume. However, decomposers feed on decaying materials.
  • These organisms are a crucial part of the environment’s food chain, as they decompose the organic and nutritional matter of the dead, so recycling the organic matter and making it available to the ecosystem.
  • This organic and nutritious stuff is absorbed or taken up by the plants or producers of the environment, and consequently, these important components enter the food cycle again. Decomposers interact with the ecosystem in this manner.
  • Decomposers occupy the lowest place in the ecological pyramid, yet they provide the essential foundation for the life in the tiers above.
  • The decomposers are heterotrophic because they obtain their energy from decomposing materials.
  • Decomposers are saprophytes, which are creatures that obtain their nutrition by feeding on dead or decaying organic matter (‘sapro’ means “rotting stuff” and ‘phyte’ means “plant”).
  • Saprophytes or decomposers are the most fundamental component of soil ecology because they feed on dead matter, which is then broken down into vital molecular elements such as carbon, calcium, nitrogen, etc. and made available to plants.
  • Saprophytes perform digestion externally, or outside of their bodies. Saprophytes produce digestive enzymes to decompose dead organic matter and turn it into simpler compounds.
  • Saprophytes, for instance, decompose proteins into amino acids, carbs into simple sugars, and fats/lipids into fatty acids and glycerol.
  • Fungi and bacteria are the most prevalent saprophytes that rely on saprophytic nourishment for survival.
  • The optimal conditions for the survival and growth of saprophytes include the presence of oxygen, high humidity/moisture, neutral or acidic pH, and temperatures between 1 and 35 degrees Celsius (25 degrees Celsius being optimal).
  • Yeast, mucor, and Penicillium are examples of organisms that are saprophytic. These saprophytes have some characteristics:
    • Have filaments
    • Having no leaves, roots, or stem.
    • Heterotrophic because it is incapable of photosynthesis
    • Produce spores

Importance of Decomposers

  • Decomposers take apart dead plants and animals. From the decomposition, nutrients and energy are recycled and put back into the ecosystem to be used again.
  • Fungi are the main organisms that break down dead matter in many ecosystems, especially forests. They help get phosphorus and nitrogen out of dead things.
  • Decomposers clean up dead things by breaking them down. They also return nutrients to the soil, which is important for producers.
  • The biogeochemical cycle of an ecosystem is kept going by decomposers. If the process of decomposition is hurt or dies, the whole ecosystem is changed.
  • Decomposers break down dead things and make room in the biosphere for new things or new life.
  • They help put nutrients and other important elements like calcium, nitrogen, and phosphorus back into the water, soil, and air so that a producer, like a crop plant, can use them again.
  • The food chain works because of decomposers. They turn a dead organic compound into a simpler inorganic compound so the grower can use it to grow.
  • They are in charge of fixing nitrogen in the soil. They change nitrogen into simpler forms like ammonia, nitrate, and nitrite that other plants and animals in the food chain can use.

Types of decomposers

There are essentially four types of decomposers: fungi, insects, earthworms, and bacteria.

1. Fungi

  • Fungi are heterotrophic organisms. They do not engage in photosynthesis and are the ecosystem’s primary decomposers.
  • Algae, which are a separate category of organisms, are not decomposers; in fact, they are producers since they possess pigments that enable photosynthesis.
  • Therefore, although algae are the producers in a food chain, fungi are the decomposers. And because mushrooms are fungi, they are also considered decomposers.
  • Fungi are the decomposers that decompose litter by pre-digesting, i.e., by releasing enzymes into the environment to breakdown litter.
  • In the process of digestion, the fungal’s enzymatic secretion decomposes dead materials, which is eventually taken up or absorbed by the fungi.
  • Fungi are classed as saprotrophs due to the fact that they breakdown dead stuff and derive nutrition from it.
  • High humidity is required for the growth and survival of fungus as well as the breakdown process.

2. Insects

  • Flies, dung beetles, maggots, and ants are insects that aid in the decomposition process in the environment.
  • Insects are classified as detritivores because they perform internal digestion of detritus in their digestive system. 
  • There are numerous types of insects that participate in decomposition, which are categorised according to the sort of decaying matter they consume:
    • Insects feed on plant tissue that has died or decayed.
    • Dead animals or insects that feed on tissue.
    • Excreta-consuming insects (eg: Arthropods like the dung beetle).

3. Earthworms

  • Detritivores are organisms that consume dead matter (of both plant and animal origin) and faeces orally and decompose litter in their digestive tracts.
  • Earthworms are the prototypical worms that replenish the soil by digesting organic matter.
  • Dead matter and faeces are consumed by earthworms, and in their intestinal tract, enzymes break down the litter, which is then excreted by the earthworm into the soil.
  • These worms enrich the soil with vital nutrients such as phosphate and calcium, among others. Worms play a crucial part in the soil’s ecology.

Bacteria

  • The process of decomposition is led by these tiny organisms that are everywhere.
  • Bacteria help recycle important nutrients like nitrogen, carbon, and others so that they can be used by the producers in the food chain.
  • Saprotrophs are also made up of bacteria.

Stages of decomposition

Every living thing on Earth will die at some point. For life to keep going on Earth, the process of decomposition must start when someone dies. Decomposition is the most important part of recycling important things back into the food cycle. The process of breaking down is mostly made up of five steps.

1. Fragmentation

  • At this stage, the dead mass is broken up, as the name suggests. This means that the big pieces are broken up into smaller ones.
  • When the large mass is broken up, it spreads out over a larger area.
  • This is the first step in the process of decomposition, which is done by detritivores.
  • The detritivores eat the dead mass, and the large mass of dead matter is broken up in their stomachs so that the decomposers can work on it.

2. Leaching

  • Fragmented detritus has a lot of water-soluble nutrients that are both organic (made up of simple compounds) and inorganic.
  • Leaching is the process by which the water that moves through the soil dissolves these water-soluble nutrients and adds them to the soil.

3. Catabolism

  • Once the detritus is broken up and the water-soluble nutrients have been taken out, the decomposing fungi and bacteria release enzymes that break down the rest of the detritus.
  • These enzymes break down the waste even more so that it can be turned into simple molecular nutrients.

4. Humification

  • The next step after the process of catabolism is the process of humification. The process by which humus is made is called “humification.”
  • Humus is the dark, amorphous layer on the soil that is full of nutrients and has a dark colour.
  • This layer is very resistant to what the microbes do to it. This layer of soil makes a big difference in how fertile the soil is.

5. Mineralization

  • In the last step of decomposition, inorganic substances like Ca+2, Mg+2, K+1, NH4+1, etc. are released into the soil along with CO2 and H2O. This makes the soil even more rich in nutrients.

6. Nutrient Immobilization

  • Some soil nutrients can’t be used by other organisms because they are bound to the microbial biomass when certain conditions are met during decomposition.
  • Nutrient immobilisation is the process by which nutrients become a part of the living microbes.
  • Though, the length of time that these nutrients stay inactive and are available varies, and they may not become mineralized until after microorganisms die.
  • This keeps nutrients from being washed out of the ecosystem by stopping them from being able to move around.

Factors affecting decomposition

There are a number of things that affect how fast things break down.

  • Quality of Litter: The structure and chemistry of the litter have a big effect on how fast it breaks down. For example, the fact that bryophytes leave behind lignin means that they break down more slowly.
  • Temperature: It is a well-known fact that microorganisms grow and do things based on the temperature. So, the process of decomposition is also affected by how the temperature changes in different geological settings. When the temperature goes down, as it does at higher altitudes where the air is cooler, the process of decomposition goes much more slowly. This is because microbial growth is slow when temperatures are low.
  • Aeration: Most decomposers, especially bacteria that break down matter, are aerobic. So, oxygen is an important part of the process of breaking down. In the pores of the soil, there is oxygen.
  • Soil pH: The decomposition process will go faster if the decomposers can grow well in the soil. Most decomposers do best when the pH is neutral or slightly acidic. A pH that is too high doesn’t help things break down. With the help of formaldehyde, this principle is used to fix a piece of tissue or organ on a slide so that it can be seen under a microscope.
  • Inorganic Chemicals: The rate at which trash breaks down depends on its chemical makeup. Minerals that don’t come from living things can slow down the process of decay.
  • Moisture: For microbes to be able to live and do their jobs, they need water or humidity. So, the amount of water affects how fast the microbes grow, which in turn affects how quickly the matter breaks down.

Difference between Decomposers and Detritivores

Decomposers are a group of organisms that break down organic matter that has already died. There are two main types of decomposers: detritivores, which eat dead things, and saprotrophs, which eat living things. Animals that break down dead matter are examples of detritivores, while fungi and bacteria are examples of saprotrophs. Decomposers and detritivores are two different words, even though they are sometimes used interchangeably. Even though “decomposer” is a broader term that can include both saprotrophs and detritivores.

TopicDecomposersDetritivores
DefinitionDecomposers are a larger group of living things that break down dead matter. Some of them eat dead things and some eat living things.Detritivores are organisms that eat dead things in order to get the nutrients and energy they need.
ExamplesFungi, bacteria, earthworms, and insects are all examples of decomposers.Millipedes, earthworms, crabs, flies, and so on are all examples of detritivores.
RoleDecomposers break down dead matter by doing things like making enzymes and digesting it on the outside.Detritivores help dead things break down by eating them and then digesting them in their stomachs.
Dead matter DecompositionThe clumps of dead matter can’t be broken down by decomposers.Detritivores can eat a lot of dead matter at once.

Difference between Decomposers and Scavengers

Topic ScavengersDecomposers
DefinitionStart the decomposition process by breaking up the dead body into small pieces.Act on the small particles that the scavengers have made available and break them down even more to get to the basic elements like carbon, calcium, phosphorous, etc.
RoleStarters of the process of breaking downThe last step in the process of decay
ExamplesBirds (like vultures), fish, crabs, and insects (like cockroaches and flies),Bacteria, fungus, and invertebrates (e.g. earthworms and millipedes)

Function of Decomposers

The main job of decomposers is to break down or “decompose” dead organisms.

1. Ecological cleansers and balance providers

  • Decomposers clean up the environment by breaking down dead animals and plants.
  • By breaking down the dead, decomposers also help make a place for new life to live. So, decomposers are a very important part of the ecosystem because they keep things in balance.

2. Recycling of nutrients

  • Decomposers break down dead matter into its basic parts, such as carbon, oxygen, nitrogen, phosphorus, etc., so that plants can use these primary essential elements. This is called recycling nutrients.
  • They can be taken in by the producers of the food chain, like plants and algae. Decomposers provide the “producers” in the food chain with the nutrients they need to stay alive.
  • Even though decomposers are at the bottom of the food web, they are the most important part of the web.

Examples of Decomposers

There are many different kinds of decomposers in each ecosystem. Depending on the terrain or the ecosystem, the kinds of decomposers are enlisted below.

Examples of Decomposers in the aquatic ecosystem

Oceans/ Seawater decomposers

The decomposers in the sea and oceans tend to grow and stay alive in warm, tropical places like the Pacific Ocean. Some of the most common things that break down in the oceans and seawater are:

  • Christmas tree worms use their feathery appendages to catch organic matter that floats in the air.
  • People say that crabs are the scavengers of the sea.
  • Granulated sea star moves along the rocky surface to clean up dead things in the water.
  • Hagfish are scavengers that eat dead things in the water and get nutrients from them.
  • Sea urchins are both eaters and decomposers. They eat the dead matter on Scarpe rocks.
  • Tube worm.

Freshwater decomposers

Most decomposers in this area live at the bottom of rivers, ponds, or lakes. Some of the most common things that break down freshwater are:

  • Mildew is a type of sea bacteria.
  • The trumpet snail is a scavenger that lives in fresh water and is seen as a pest.
  • Water mould, clean water, or a bacterium in the soil.
  • Yeast and bacteria from fresh water.

Examples of Decomposers in Terrestrial Ecosystem 

Forest Ecosystem Decomposers

There are different decomposers in a forest bed. Here are some of them:

  • Beetles, which eat dead things, are the shredders.
  • Earthworms eat dead things.
  • Millipede, another animal that eats trash and shreds things.
  • Mushrooms are fungi that grow on the ground or on things that have died.
  • Pillbugs are another type of shredder that eats trash.
  • Saprobe is a type of soil bacteria.
  • On the damp, rotten wood and leaves, there was a slimy mould that looked like saprobe.
  • Slug is another creature that eats trash and shreds things.

Desert Ecosystem Decomposers

Deserts are low-humidity ecosystems, so normal decomposers like fungi and bacteria don’t live there. In the desert ecosystem, only insects break down dead things. Here are a few of them:

  • The dung beetle, bacteria that feed on animal waste.
  • Flies are insects that eat dead things.
  • Millipede, insects eat decaying plant matter.
  • The Saharan silver ant is a desert ant that eats dead animals.

Grassland Ecosystem Decomposers

This can be like a desert with a forest ecosystem. Some common examples include:

  • Acidobacteria is a type of bacteria that lives in grasslands or savannas. Termites are insects that eat wood by breaking down its cellulose.
  • Fungi that feed on dead trees have names like turkey tail and mushroom.

Mountain Ecosystem Decomposers

These are also like decomposers in a forest ecosystem. Here are some examples:

  • Fungi like boletes feed on the waste products of ponderosa pine trees.
  • Mountain pine bark beetle, which feeds on dying and dead trees
  • Purple fairy fingers are caused by fungus that grows on dead trees.

References

  • https://education.nationalgeographic.org/resource/decomposers
  • https://thebiologynotes.com/decomposers-definition-types-examples/
  • https://en.wikipedia.org/wiki/Decomposer
  • https://www.qrg.northwestern.edu/projects/marssim/simhtml/info/whats-a-decomposer.html
  • https://nhpbs.org/natureworks/nwep11b.htm
  • https://www.scienceworld.ca/resource/decomposers/
  • https://byjus.com/question-answer/a-define-decomposers-name-one-decomposer-b-what-is-the-role-of-decomposers-in-the/
  • https://biologydictionary.net/decomposer/
  • https://byjus.com/question-answer/what-are-decomposers-name-any-two-of-them-what-do-they-do-in-the-forest/
  • https://www.lidolearning.com/questions/s-bb-ncert7-ch17-ex-q3/q3-what-are-decomposers-name-a/
  • https://www.biologyonline.com/dictionary/decomposer
  • https://study.com/academy/lesson/what-is-a-decomposer-definition-examples.html
  • https://www.merriam-webster.com/dictionary/decomposer
  • https://www.expii.com/t/decomposer-definition-role-10471
  • https://www.rspb.org.uk/birds-and-wildlife/natures-home-magazine/birds-and-wildlife-articles/food-chains/decomposers/
  • https://www.vocabulary.com/dictionary/decomposer
  • https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/decomposer
  • http://web.mit.edu/12.000/www/m2007/teams/7/final_report/decomposers.html
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