Bacteria go to extreme lengths to handle the tough times: they dig in, build a fortress-like shell around their DNA, and shut down all signs of life. And yet, when times improve, these dormant spores can resurface from what appears to be dead.
But “you have to be careful when you decide to come back to life,” says Peter Setlow, a biochemist at UConn Health in Farmington. “Because if you’re wrong, you die.” How do you say a spore?
For the spores of the bacteria. Bacillus subtilisThe solution is simple: Account.
These “living rocks” sense it’s time to revive or germinate, essentially counting how often they find nutrients, researchers report in a new study published Oct. 7. Sciences.
“It appears that they have literally no measurable biological activity,” says Gürol Süel, a microbiologist at the University of California, San Diego. But Süel and his colleagues knew that spore nuclei contain positively charged potassium atoms, and because these atoms can move around without the cell using energy, the team suspected that potassium might be involved in waking up cells. .
Then the team exposed B.subtilis spores to nutrients and used colorful dyes to track the movement of potassium out of the nucleus. With each exposure, more potassium leaked out of the nucleus, changing its electrical charge to be more negative. Once the spore nuclei were sufficiently negatively charged, germination was triggered, like a bottle of champagne finally being popped. The number of exposures needed to trigger germination varied by spore, just as some corks require more or less twisting to pop. Spores whose potassium movement was paralyzed showed a limited change in electrical charge and were less likely to “highlight” no matter how many nutrients they were exposed to, the team’s experiments showed.
Changes in a cell’s electrical charge are important throughout the tree of life, from determining when brain cells send messages to each other to breaking a venus fly trap (Serial Number: 10/14/20). Finding out that the spores also use electrical charges to activate their calls for attention excites Süel. “You want to find principles in biology,” she says, “processes that cross systems, that cross fields and borders.”
Spores are not only interesting for their unique and extreme biology, but also for their practical applications. Some “can cause some pretty nasty things,” from food poisoning to anthrax, says Setlow, who wasn’t involved in the study. Since the spores are resistant to most antibiotics, understanding germination could lead to a way to bring them back to life to kill them for good.
Still, there are many unanswered questions about the “black box” of how spores begin to germinate, such as whether it is possible for the spores to “reset” their potassium level. “We’re really in the early days of trying to fill in that black box,” says Kaito Kikuchi, a biologist now at Reveal Biosciences in San Diego who did the work while at the University of California, San Diego. But discovering how the spores manage to track their environment while being more dead than alive is an exciting start.