A bacterium can be longer than a fly
Thiomargarita magnifica, from Caribbean mangroves, has cells averaging longer than nine millimetres. They are visible without a microscope. The DNA sits in membrane-bound compartments.
Most bacterial cells are around two micrometres. A fruit fly is a few millimetres. Cells of Candidatus Thiomargarita magnifica average above nine thousand micrometres — just under a centimetre — and were found on sunken leaves in the mangroves of Guadeloupe. They are single cells. They are still bacteria. They are large enough that the old size limit, set by how fast food can diffuse in and waste can diffuse out, had to be redrawn.
The redrawing has a structure. The genome is not floating loose. It is held, with ribosomes, in small compartments bounded by membranes, and a cell carries hundreds of thousands of copies of that genome. That is not a nucleus, and it is not a eukaryote. It is a bacterium that has started to keep its instructions in rooms. The name is still a candidate name. The cells are not.
Caveats
- ‘Longer than a fly’ is the length of the cell against the length of a fruit fly. It is not a claim about mass, or that this is typical of bacteria.
- The compartments are not a nucleus. The lineage has not become a eukaryote by being large.
Sources
- 1Volland J.-M. et al.. A centimeter-long bacterium with DNA contained in metabolically active, membrane-bound organelles. Science 376, 2022.