Microbiology

Monsters in the Mangrove

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Science  03 Sep 2010:
Vol. 329, Issue 5996, pp. 1129
DOI: 10.1126/science.329.5996.1129-c

Ovoid bacteria coating filamentous archaea.

CREDIT: MULLER ET AL., ENVIRON. MICRO. 12, 2371 (2010)

Life on Earth has been classified into three domains: the Bacteria and the Archaea are single-celled microbes lacking nuclei, and the nucleated Eukarya possess a combination of archaeal- and bacterial-like genes. There are some interesting exceptions to the general smallness of life (apart from us), and Muller et al. have discovered mats of long (30 mm) white filaments attached to the roots of mangrove trees in Guadaloupe. These filaments are two new species in a recently discovered phylum within the Archaea. One type of filament is coated with a single-cell layer of a γ-proteobacterium, which contains large globules of sulfur. The other, uncoated filament was found only where the gregarious species was abundant. The associated bacteria may be symbionts that scrub out otherwise toxic sulfide oozing up from the mangrove swamp sediment, and this detox process in turn could allow the less abundant archaean to survive. Metabolites might not be the only chemicals shared, and the authors speculate that this could represent an example of an evolutionary step in cellular complexity that might also involve the exchange of genes.

Environ. Micro. 12, 2371 (2010).

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