Certain strains of bacteria have evolved a way of providing for neighboring cells after they die, giving up a feast of nutrients as a legacy that other bacteria can use to survive and grow.
Researchers from Durham University in the UK observed the behavior in colonies of the microbe Escherichia coli, though their findings are likely to apply to other species and perhaps even other kinds of organism.
Using a combination of imaging techniques, statistical analysis, and bacterial growth measurements, the team identified an enzyme called Lon protease, which dismantles proteins and turns them into simpler peptides for cells to use.
While the breakdown and regulation of proteins is something Lon protease was already known for, this is the first time scientists have recorded its activity continuing after a cell’s death, highlighting the enzyme’s benefit not just for the individual expressing it but for other nearby bacteria.
“This discovery highlights an unexpected post-mortem biochemistry, reshaping our understanding of nutrient recycling,” write the researchers in their published paper.
The team also engineered bacterial samples without the Lon protease gene, showing that the enzyme was crucial for this behavior after death. However, non-Lon protease bacteria can still benefit from the nutrients produced, even if they don’t contribute the enzymes themselves.
It’s an example of a cooperative social adaptation: the bacteria has evolved to not just help itself survive, but also to try and benefit its own clones after it’s gone, using some of its natural recycling processes.
“Those processes continue after death, and they have evolved to do so,” says biochemist Martin Cann, from Durham University.
“That is a fundamental rethink about how we view the death of an organism.”
This idea could be expanded further: studies into green algae and leaf litter have suggested other organisms may exhibit similar traits, dying and decomposing in a way that helps the surrounding ecosystem and therefore its own descendents.
While bacteria might not be able to leave behind a family home or a lump sum of cash to their closest friends and relatives, it appears they can still contribute to the bacteria community, and indeed they’re programmed to do so.
It’s still early days for this area of research, but eventually we might even be able to control some of these post-mortem processes, in ways that limit growth in bacterial disease or promote growth in beneficial biotech applications.
“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,” says Cann.
“But what this paper has demonstrated is that death is not the end of the programmed biological processes that occur in an organism.”
The research has been published in Nature Communications.
