Bacterium discovery helps to unravel the puzzle of what elements restrict cell dimension

On sunken leaves within the waters of a Caribbean mangrove swamp, researchers found a bacterium that challenges the prevailing view of bacterial cell dimension; counter to the notion that microbes are solely seen with a microscope, this one – named Thiomargarita magnifica – is bigger than all different recognized big micro organism by ~50-fold, and will be seen by the bare eye, the examine’s authors say. It is also fairly complicated in its construction, additional difficult conventional ideas of bacterial cells. “This discovery provides to the group of enormous sulfur micro organism and helps to unravel the puzzle of what elements restrict cell dimension,” writes Petra Anne Levin in a associated Perspective.

Micro organism are generally regarded as microscopic single cells with DNA free-floating of their cytoplasm. As a gaggle, nevertheless, they typically present a shocking vary of range. On this examine, Jean-Marie Volland et al. add to this range by reporting the invention and characterization of a sulfur-oxidizing bacterium that may develop orders of magnitude over theoretical limits for bacterial cell dimension, with a posh membrane group that possible allowed it to develop to such dimension, circumventing typical biophysical and bioenergetic limitations.

The organism was first found rising as skinny white filaments on the surfaces of decaying mangrove leaves in shallow tropical marine mangrove swamps in Guadeloupe, Lesser Antilles.

Utilizing a variety of strategies, Volland and colleagues aimed to characterize it. Although micro organism are sometimes seen solely with a com­pound microscope able to magni­fying 100 to 1,000 instances, this one – reaching one centimeter in size – is seen with no microscope. And, as an alternative of its DNA floating freely contained in the cell as occurs in different micro organism, the DNA is compartmentalized inside membrane-bound buildings, an innovation attribute of extra complicated cells. These membrane-bound compartments are metabolically energetic, the authors’ analyses present, with exercise occurring all through the bacterium cell size, versus simply at its rising tip. It’s doable that this distinctive spatial group and bioenergetic membrane system, which point out a acquire of complexity within the Thiomargarita lineage, might have allowed T. magnifica to beat size- and volume-related limitations sometimes related to micro organism.

Why these organisms have to be so massive is an intriguing, open query, says Levin within the associated Perspective, the place she additionally suggests it unlikely that T. magnifica represents the higher restrict of bacterial cell dimension. “… micro organism are endlessly adaptable and at all times surprising-;and will by no means be underestimated,” writes Levin. The authors conclude: “The invention…suggests that enormous and extra complicated micro organism could also be hiding in plain sight.”

Journal reference:

Volland, J.M., et al. (2022) A centimeter-long bacterium with DNA contained in metabolically energetic membrane-bound organelles. Science. doi.org/10.1126/science.abb3634.

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