Natures wonders: cooperating bacteria (Introduction)

by David Turell , Wednesday, July 20, 2022, 20:11 (855 days ago) @ David Turell

A new form is found:

https://www.the-scientist.com/news-opinion/inside-versus-out-a-new-form-of-bacterial-co...

"Oceanic bacteria form a transient spherical community to conquer large food sources, taking on different roles to break down the bounty more efficiently.

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"While she expected the bacteria to aggregate in haphazard clumps, V. splendidus had grown into neat, nearly perfect spheres. These bizarre colonies, described June 30 in Current Biology, turned out to be a previously unknown form of bacterial self-organization. And although these clustered cells share the same genes, Schwartzman and her colleagues found that they expressed them differently based on their location in the sphere, taking on starkly different roles in their miniature community.

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"Typically, bacteria engage in this sort of cooperation by forming biofilms and other aggregates, in which they’re glued together by a dense extracellular matrix. In this form, they can share nutrients and genetic information. Indeed, Schwartzman had previously observed that V. splendidus clump up when suspended in liquid media, but the colonies that the bacteria formed this time around were much neater and more organized than she expected. By observing these colonies through a microscope, the researchers realized that as the cells divided and created a tight cluster and started to take on different properties depending on their location in the clump. Those along the margins moved very little, creating a static shell, while those in the core continued to move around. Both types of cells then continued to grow and divide until the interior cells eventually burst out through their external companions, leaving a hollow sphere. After the rupture, the authors speculate that the cells remaining in the shell die off while the escapees go on to form new colonies, pointing out that this bursting behavior, which the scientists described as a three-stage process, is similar to how fungi and other organisms propagate.

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"After observing the two phenotypes that create such structured colonies, Schwartzman employed a battery of techniques to understand how they emerge. RNA sequencing revealed that the core and shell populations were transcriptionally different. The cells in the shell were pumping out filamentous protein structures called type 4 pilli that can expand and retract—Schwartzman likens them to “active Velcro.” This is likely how these outer cells stick to each other and keep the structure contained.

"Meanwhile, the cells in the core activated genes for making lipids, which Schwartzman says was likely a way of stockpiling carbon that the colony could use as it grew.

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"In the wild, they explain, these bacteria are likely using the division of labor strategy to take advantage of temporary feasts. V. splendidus spend the majority of their lives as single cells floating around in ocean water looking for food, the researchers say. Once they find an abundant source, the divison of labor strategy allows them to break down and store complex sugars quickly and efficiently."

Comment: another form of cooperation as we see in slime mould and I assume stromatolites. The RNA study shows how the mechanism is coded into DNA.