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A centimeter-long bacterium with DNA contained in metabolically active, membrane-bound organelles
Ist Teil von
Science (American Association for the Advancement of Science), 2022-06, Vol.376 (6600), p.1453-1458
Ort / Verlag
Washington: The American Association for the Advancement of Science
Erscheinungsjahr
2022
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
Cells of most bacterial species are around 2 micrometers in length, with some of the largest specimens reaching 750 micrometers. Using fluorescence, x-ray, and electron microscopy in conjunction with genome sequencing, we characterized
Candidatus
(
Ca.
) Thiomargarita magnifica, a bacterium that has an average cell length greater than 9000 micrometers and is visible to the naked eye. These cells grow orders of magnitude over theoretical limits for bacterial cell size, display unprecedented polyploidy of more than half a million copies of a very large genome, and undergo a dimorphic life cycle with asymmetric segregation of chromosomes into daughter cells. These features, along with compartmentalization of genomic material and ribosomes in translationally active organelles bound by bioenergetic membranes, indicate gain of complexity in the
Thiomargarita
lineage and challenge traditional concepts of bacterial cells.
A magnificent megabacterium
We usually think of bacteria as microscopic isolated cells or colonies. Sampling a mangrove swamp, Volland
et al
. found an unusually large, sulfur-oxidizing bacterium with a complex membrane organization and predicted life cycle (see the Perspective by Levin). Using a range of microscopy techniques, the authors observed highly polyploid cells with DNA and ribosomes compartmentalized within membranes. Single cells of the bacterium, dubbed
Candidatus
Thiomargarita magnifica, although thin and tubular, stretched more than a centimeter in length. —MAF
Candidatus
Thiomargarita magnifica contains compartmentalized genomic material and disrupts conceptions of microbial morphology.