Survival at a price: Bacteria cut off flagella to stay alive

Bacteria have a survival plan for when they are starving:

Some bacteria use tails, or flagella, to swim through liquids—including those in our bodies. However, new research published today in PLOS Biology reveals a surprisingly drastic measure taken by some bacteria when facing starvation: they eject their flagella, leaving themselves paralyzed, but conserving energy so they can stay alive…

First author Josie Ferreira, from the Department of Life Sciences at Imperial, said: “Before we started our experiments, we thought we had caught the bacteria in the process of assembling their motor-flagella complexes. To our surprise, we found the opposite: not only had the bacteria ejected their flagella, they had plugged the hole it left behind. This suggested to us it was a deliberate action.”

Bacterial use their flagella to get around, even swimming through thick gut mucus as in the case of food-poisoning bacterium Campylobacter jejuni. However, flagella are costly to build and power, and constantly grow throughout the bacteria’s life, using up a lot of resources.

The team found that bacteria placed in environments that lacked nutrients ejected their flagella into the growth medium. The discarded flagella were complete, including the adaptor structure that connects flagella to their motors, suggesting that they were ejected whole from their base, and not broken off.

Lead author Dr. Morgan Beeby, from the Department of Life Sciences at Imperial, said: “The bacteria’s actions appear to be deliberate. It’s not like when our fingers or toes drop off from frostbite—it’s more a calculated act like mountaineer Aron Ralston cutting off his arm in the film 127 Hours to free himself from under a rock.”

Bacteria have been observed swimming more slowly when nutrients are low, but this is the first time they have been observed jettisoning their flagella completely in a bid to save energy. Imperial College London, “Starving bacteria can eject their tails to save energy and stay alive” at Phys.org

But how can bacteria be smart enough to know that they should develop a mechanism to do that safely? That’s like the female birds who supposedly choose the sex of their offspring according to the population of mates and plan for their future. Or the male bees who supposedly know that they can mate with the female offspring of other bees that they help raise. Or the mares who supposedly cause an abortion because they perceive that the stallion will not accept his offspring.

The world of Darwinian evolution features so many exceptionally clever animals that are nothing like the humdrum creatures we must tie down or tranquillize in order to help. And the profs just attribute it all to natural selection, as if that would explain anything in a situation where some prevision seems required.

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Hat tip: Philip Cunningham

See also: Symbiotic bacteria help frogs find mates (but the real story is all the assumptions that got corrected) Contrary to assumption, 1) smell was important in locating mates and 2) males and females had different smells 3) produced by symbiotic bacteria. One wonders how many other life forms would challenge simple evolution tales if they were closely studied.