Genome complexity: are bacteria truly independent ? (Introduction)

by David Turell , Monday, March 04, 2019, 18:26 (1881 days ago) @ David Turell

A new study on fluid flow and unicellular organisms shows they go with the flow:

https://phys.org/news/2019-03-microbes-mathematical.html

"Freeing thousands of microorganisms to swim in random directions in an infinite pool of liquid may not sound like a recipe for order, but eventually the swarm will go with its own flow.

"Theoretical modeling led by University of Wisconsin–Madison applied mathematician Saverio Spagnolie shows that the forces generated by different kinds of tiny swimmers will sweep them all up in predictable ways.

"'When each individual particle experiences the flows created by all the other particles, it's known that really surprising effects can naturally emerge," says Spagnolie. "The flows and orientations of the swimmers become coherent on a length scale much longer than any individual particle, resulting in huge flocks of organisms swimming in the same direction and, perhaps unintentionally, working together."

***

"The researchers worked out the relevant equations for particles that move by various means—swimmers that actively push or pull themselves through fluid, and types (like microtubules inside a cell) that push or pull themselves through molecular means without active appendages like flagella—and goosed them into motion.

"'From that perturbation there's this explosion of motion," Spagnolie says. "And then we watch how the different forces play out on different types of particles."

"While a tight colony of pulling swimmers, for example, stretches itself out in a line perpendicular to the direction they're headed, a colony of pushers stretches quickly in the direction of motion, and then bends on itself over and over in a cascade of shrinking folds.

"'That these individuals can group together passively due to their fluid interactions alone, and that this results in large-scale events and effects they can't achieve as independent particles, is relevant to many biological functions—like nutrient mixing and bacterial resistance to antibiotics in bacterial swarms and biofilms," Spagnolie says."

Comment: In this instance bacteria appear to be mostly passive.