Bacterial Intelligence? sensing surfaces (General)

by David Turell , Friday, October 27, 2017, 15:18 (2582 days ago) @ David Turell
edited by David Turell, Friday, October 27, 2017, 15:37

A new study shows that bacteria can use their flagellum to sense a surface:

https://www.sciencedaily.com/releases/2017/10/171026142320.htm

"Although bacteria have no sensory organs in the classical sense, they are still masters in perceiving their environment. A research group at the University of Basel's Biozentrum has now discovered that bacteria not only respond to chemical signals, but also possess a sense of touch. In their recent publication in Science, the researchers demonstrate how bacteria recognize surfaces and respond to this mechanical stimulus within seconds. This mechanism is also used by pathogens to colonize and attack their host cells.

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"Swimming Caulobacter bacteria have a rotating motor in their cell envelope with a long protrusion, the flagellum. The rotation of the flagellum enables the bacteria to move in liquids. Much to the surprise of the researchers, the rotor is also used as a mechano-sensing organ. Motor rotation is powered by proton flow into the cell via ion channels. When swimming cells touch surfaces, the motor is disturbed and the proton flux interrupted.

"The researchers assume that this is the signal that sparks off the response: The bacterial cell now boosts the synthesis of a second messenger, which in turn stimulates the production of an adhesin that firmly anchors the bacteria on the surface within a few seconds. "This is an impressive example of how rapidly and specifically bacteria can change their behavior when they encounter surfaces," says Jenal."

Comment: the disturbed flagellum can easily be seen as an automatic signal to produce adhesin, following intelligent instructions in the DNA. Following a 'mechanosensitive channel'.

Note the study abstract: http://science.sciencemag.org/content/358/6362/531

When bacteria encounter surfaces, they respond with surface colonization and virulence induction. The mechanisms of bacterial mechanosensation and downstream signaling remain poorly understood. Here, we describe a tactile sensing cascade in Caulobacter crescentus in which the flagellar motor acts as sensor. Surface-induced motor interference stimulated the production of the second messenger cyclic diguanylate by the motor-associated diguanylate cyclase DgcB. This led to the allosteric activation of the glycosyltransferase HfsJ to promote rapid synthesis of a polysaccharide adhesin and surface anchoring. Although the membrane-embedded motor unit was essential for surface sensing, mutants that lack external flagellar structures were hypersensitive to mechanical stimuli. Thus, the bacterial flagellar motor acts as a tetherless sensor reminiscent of mechanosensitive channels.