← No. 016 THU 15 OCT 2026

One bacterium is visible without a microscope.

Thiomargarita magnifica — Guadeloupe mangroves

Scientists described a single bacterial cell that grows to about the length of a small sewing pin and lives on mangrove leaves in Guadeloupe. It is not a chain of cells but one giant cell. Inside, its genetic material is tucked into many membrane‑wrapped pockets—unusual for bacteria. This outsized microbe stretches what we thought were hard limits on cell size and organization.

Why it’s interesting

Fig. 016 Length scaled to about two centimetres; the inner dots mark DNA‑filled compartments set around the cell’s rim.

Why it’s interesting

It blurs lines we drew between “simple” bacteria and complex cells, and shows that even a single cell can reach the size of something you could pick out on a leaf.

The longer version

In 2022, researchers reported a giant bacterium named Candidatus Thiomargarita magnifica. Each filament is one cell, large enough to see with the naked eye—often around a centimeter long and sometimes reaching roughly two. It lives on decaying mangrove leaves where sulfur is abundant, using that chemistry to power its life.

Using microscopy, 3‑D imaging and genome work, the team showed that its DNA and ribosomes sit inside numerous membrane‑bound compartments nicknamed “pepins.” That arrangement, rare in bacteria, helps explain how a cell this large keeps its machinery organized and active across such a span. The finding was peer‑reviewed in Science (June 24, 2022).

Edition: No. 016
Date: Thursday 15 October 2026
Subject: Thiomargarita magnifica
Locality: Guadeloupe mangroves
Period: 2022
Field: life
Evidence: 4 sources, 1 primary

See how we got here

Found after 27 research paths · Selected from 12 candidates

01 Bacteria Most are too small to see.
02 Cell size limits Diffusion and organization set constraints.
03 Sulfur microbes Life that feeds on sulfur in low‑oxygen places.
04 Giant sulfur bacteria A few reach millimeter scale.
05 Thiomargarita magnifica One cell, centimeter‑long, DNA in membrane pockets.
→ One bacterium is visible without a microscope.

Sources

Nothing publishes without independent sources. How we verify →

1
A centimeter-long bacterium with DNA contained in metabolically active, membrane-bound organelles
PubMed record of Science (AAAS) article · 2022 · peer reviewed Primary

Centimeter-long single cell; DNA and ribosomes in metabolically active, membrane‑bound organelles; overall primary description and DOI 10.1126/science.abb3634.

pubmed.ncbi.nlm.nih.gov
2
The world's largest bacteria are visible to the naked eye
Natural History Museum (London) · 2022 · museum

Up to two centimetres in length; DNA packaged in membrane‑bound compartments (‘pepins’).

nhm.ac.uk
3
A centimeter-long bacterium with DNA contained in metabolically active, membrane-bound organelles (archival entry)
DOE Joint Genome Institute (AAAS/Science article metadata) · 2022 · scientific organization

Confirms citation details (Science 376:1453–1458; DOI 10.1126/science.abb3634) and summarizes membrane‑bound organelles with DNA and ribosomes.

archive.jgi.doe.gov
4
Biggest bacterium ever discovered shakes our view of the single-celled world
National Geographic · 2022 · journalism

It is a single bacterial cell; genetic material stored in membrane‑bound compartments ‘pepins’.

nationalgeographic.com

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