First multicellularity: claimed in bacterial mats (Evolution)

by David Turell , Tuesday, October 13, 2020, 18:25 (1500 days ago) @ David Turell

A new study extrapolates a study of B. subtilis mat into ontology follows phylogeny:

https://phys.org/news/2020-10-evolution-social-distancing-life.html

"In this paper, the researchers took evolutionary tools to study the growth of biofilms, the most common bacterial lifestyle characterized by the tight clustering of bacterial cells on surfaces. "Surprisingly, we found that the development of bacterial biofilms is comparable to animal embryogenesis. This means that bacteria are true multicellular organisms just like we are. Considering that the oldest known fossils are bacterial biofilms, it is quite likely that the first life was also multicellular, and not a single-celled creature as considered so far," says Prof Tomislav

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"microbiologists have recognized that bacterial cells live a rich social life in biofilms. However, it has remained unclear if these diverse interactions comprise a multicellular organism. "Evolutionary methods to study collective behavior of cells in animal development were at hand, but no one tried to transfer this technology from animal embryos to bacterial biofilms. Perhaps people were uncomfortable to challenge the special status of animal multicellularity, the idea that is culturally hardwired," says Domazet-Lošo.

"Previous work of Domazet-Lošo and his team was focused on evolutionary genomics and animal development. They were able to show that evolution is mirrored in embryos, thus confirming the old conjecture that ontogeny parallels phylogeny in animals.

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"'Surprisingly, we found that evolutionary younger genes were increasingly expressed toward the later timepoints of biofilm growth. In other words, we found that Bacillus ontogeny strongly recapitulates phylogeny. So far, these patterns have been considered the signature of embryo development in complex eukaryotes," says Domazet-Lošo. The research team then followed the trail and looked for other features of embryogenesis in biofilms like stage-organized architecture, increased use of multicellularity genes and molecular links to morphology changes, and to their excitement, they found these properties, as well."

Comment: There is no question here is an imitation of multicellular organisms. Perhaps a step to multicellularity. We know amoeba can form colonies that create stalks and spores. but I think they are straining too much to see this as true multicellularity.