May Play Underrated Role In The Environment, According To Research In 16 April 1999 Science

Washington DC -- A group of German, Spanish, and American researchers sampling sediment off the coast of Namibia have stumbled across the biggest bacteria ever known. The largest of these single-celled microbes is visible to the naked eye, about as big as the period at the end of this sentence and nearly 100 times larger than the previous bacterial record-holder. In addition to its giant size, the new microbe is an exotic organism that provides firmer evidence of coupling between two key environmental cycles thought until very recently to be mutually exclusive in the ocean: the sulfur and nitrogen cycles. The finding is described in the 16 April 1999 issue of Science.

"When I told them, my colleagues at first didn't believe me because the bacteria were so big," recalls Heide Schulz, the Ph.D. student at Max Planck Institute for Marine Microbiology who found the bacterial behemoths glistening in sediment they had pulled into the research boat. "But I've been working with exotic bacteria for a while now and I knew immediately that these were sulfur bacteria."

The researchers named the new bacteria Thiomargarita namibiensis, which means "Sulfur Pearl of Namibia." The microbes store elemental sulfur just under the cell wall as well as nitrate in a huge central sac, which shines with an opalesque, blue-green whiteness. They also grow loosely attached in strings, leading the researchers to compare them with strands of outlandish pearls. The largest cells are three-quarters of a millimeter in diameter. But to get a better idea of how big this is, it helps to make an analogy: If the largest Thiomargarita was a blue whale, then an ordinary bacterium would be a bit smaller than a new-born mouse. The largest previously known bacterium -- Epulopiscum fishelson
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Contact: Gabe Paal
gpaal@aaas.org
202-326-6421
American Association for the Advancement of Science
16-Apr-1999