A "body part" continues to live after a person's death: what are we talking about
The human body contains trillions of microorganisms (microbial symbionts) that are involved in many vital processes. They help digest food and produce vitamins, can support the immune system by protecting against infections, and perform a number of other essential functions.
Scientists have discovered that after a person dies, the microbes in their body behave in a somewhat unusual way. The necrobiome not only plays a role in "recycling" the body, but also, according to the researchers, "makes sure that new life can flourish." Read more in The Conversation.
Life after death
After a person dies, the heart stops circulating blood, which carries oxygen throughout the body. Without access to oxygen, cells begin to "digest" themselves, a process scientists call autolysis. In this process, enzymes that digest carbohydrates, proteins, and fats for energy or growth begin to affect the membranes, proteins, DNA, and other components that make up cells.
It is these cellular breakdown products that are ideal food for symbiotic bacteria. Some intestinal bacteria, especially the Clostridia class of microbes, spread to all organs and "digest" a person from the inside during the process of decay.
Scientists say that the microbes have evolved to adapt to a body that no longer receives oxygen. They can be compared to rats on a sinking ship. The bacteria are actually trying to "get full" in order to "survive in the world long enough to find a new host to colonize". In doing so, bacteria use all the nutrients in the human body.
So, a person has died and is buried in the ground. The process of decomposition begins. Microbes are actually washed into the soil along with other liquids. Thus, the microorganisms enter a new and unfamiliar environment and encounter new communities of microbes in the soil.
The researchers emphasize that in the natural world, the process of mixing or merging two different microbial communities often occurs. Examples include the growth of plant roots, sewage flowing into a river, or even the exchange of saliva when people kiss.
Microbes that have adapted to the warm and nutritious environment in the human body find themselves in a new harsh environment. Soil is an unstable environment with sharp chemical and physical gradients and significant fluctuations in temperature and humidity. Human microbes come into contact with other living organisms, often aggressive ones.
Scientists have shown that human microbes are quite resilient. DNA signatures of host-associated microbes were found in graves for months or even years after the process of soft tissue decomposition had been completed.
The researchers noted that these microbes are actually dormant, as if waiting for the next "host." They adapt to the new conditions and begin to participate in many processes (including body decomposition). Microbes also increase the nitrogen cycle and convert large nitrogen-containing molecules, such as proteins and nucleic acids, into ammonium.
The next life
Recycling nutrients from inanimate organic matter is an important process in all ecosystems.
"A single dead animal can support an entire food web of microbes, soil fauna, and arthropods that make a living off of corpses," the scientists say.
For example, insects and some animals are involved in the redistribution of nutrients. Decomposer microbes transform concentrated pools of nutrient-rich organic molecules from the human body into smaller, more accessible forms. These are then used by other microorganisms to support the life of new life.
Thus, human microbes play an important role in this cycle, ensuring life after death.
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