Dormant bacteria count to wake up at the right time

• It could also provide clues about what life is capable of in extreme conditions — and help guide the search for life on Mars or other planets.

Background: Normally, cells receive signals when a gene is expressed or another biochemical reaction occurs.

• But bacteria spores are doing "literally nothing" when they are dormant, says Gürol Süel, a microbiologist at the University of California, San Diego.
• From previous research, Süel and his colleagues knew the spores housed potassium ions. They thought the positively charged ions could be creating a pre-stored electrochemical potential in the spores — similar to a capacitor — that signaled they should wake up, or germinate.

What they found: They tested the idea by giving Bacillus subtilis short pulses of nutrients, and measuring what happened as potassium ions left a spore's core and the electrical charge in the spore became more negative.

• When the spore's capacitor reached a certain charge, it germinated.

• When the scientists engineered spores to mutate the channels the ions move through, the charge in the spore's capacitor didn't change much and the spores stayed asleep, Süel and his colleagues reported Thursday in the journal Science.

The intrigue: It's still unclear how the bacteria wake up.

• "It's still baffling to me that after thousands of years of doing nothing like that, how do they wake up in a few minutes? It's really weird," Suel says.

The big picture: The spores' counting mechanism is similar to one that determines when a Venus fly trap closes — not too soon and not too late — and when a neuron fires.

• "It's interesting to see that there's similar solutions to similar problems," Süel says.