Multicellular life cycle of magnetotactic prokaryotes

TLDR

Most multicellular organisms, including prokaryotes, animals, plants, and algae, normally have a unicellular stage, yet no unicellular bacteria resembling the cells of these magnetotactic multicellular organisms have been identified. Here, we describe an uncultured prokaryotic magnetotactic multicellular organism that reproduces by binary fission. The organism remains multicellular throughout its life cycle, forming a hollow sphere of coordinated single cells that enlarges as cells grow, then all cells divide synchronously to produce two equal elliptical spheres via a torsional equatorial movement, and genetic analysis places the population within the delta‑subgroup of proteobacteria related to many‑celled magnetotactic prokaryotes. This appears to be the first report of a multicellular prokaryotic organism that proliferates by dividing into two equal multicellular organisms each similar to the parent one.

Abstract

Most multicellular organisms, prokaryotes as well as animals, plants, and algae have a unicellular stage in their life cycle. Here, we describe an uncultured prokaryotic magnetotactic multicellular organism that reproduces by binary fission. It is multicellular in all the stages of its life cycle, and during most of the life cycle the cells organize into a hollow sphere formed by a functionally coordinated and polarized single-cell layer that grows by increasing the cell size. Subsequently, all the cells divide synchronously; the organism becomes elliptical, and separates into two equal spheres with a torsional movement in the equatorial plane. Unicellular bacteria similar to the cells that compose these organisms have not been found. Molecular biology analysis showed that all the organisms studied belong to a single genetic population phylogenetically related to many-celled magnetotactic prokaryotes in the delta sub-group of the proteobacteria. This appears to be the first report of a multicellular prokaryotic organism that proliferates by dividing into two equal multicellular organisms each similar to the parent one.