Researchers have made the surprising discovery that a type of gut bacteria has evolved to use one of their enzymes to perform an important function after death.
Darwin’s theory of natural selection provides an explanation for why organisms develop traits that help them survive and reproduce.
Because of this, death is often seen as a failure rather than a process shaped by evolution.
When organisms die, their molecules need to be broken down for reuse by other living things. Such recycling of nutrients is necessary for new life to grow.
Now a study led by Professor Martin Cann of our Department of Biosciences has shown that a type of E-coli bacteria produces an enzyme which breaks the contents of their cells down into nutrients after death.
The dead bacteria are therefore offering a banquet of nutrients to the cells that were their neighbours when they were living.
Professor Cann said: “We typically think of death being the end, that after something dies it just falls apart, rots and becomes a passive target as it is scavenged for nutrients.
“But what this paper has demonstrated is that death is not the end of the programmed biological processes that occur in an organism.
“Those processes continue after death, and they have evolved to do so. That is a fundamental rethink about how we view the death of an organism.”
The researchers found that neighbouring cells which gain nutrients from the dead cells are likely to be clonally related to the dead cell.
Consequently, the dead cell is giving nutrients to its relatives, analogous to how animals will often help feed younger members of their family group.
The study involves researchers from the University of Oxford and University of Edinburgh in the UK and has been published in the journal Nature Communications.
The finding demonstrates that processes after death, like processes during life, can be biologically programmed and subject to evolution.
Biomolecules that regulate processes after death might be exploited in the future as novel targets to bacterial disease or as candidates to enhance bacterial growth in biotechnology.
The researchers suggest that modelling such processes using the tools of statistical physics may also provide design principles for humans as we move towards a more circular economy in which recycling needs to be built in from the beginning.
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