Newspaper article The Tuscaloosa News

ECOVIEWS: Scientists Marvel at Discovery of Giant Bacteria

Newspaper article The Tuscaloosa News

ECOVIEWS: Scientists Marvel at Discovery of Giant Bacteria

Article excerpt

Blue whales reach a length of 100 feet and are the biggest animals on earth, as far as scientists know. But several years ago, you wrote about some type of microorganism that got enormous as well. What was the story?

In 1999, a type of bacteria a hundred times larger than any other known bacteria was discovered in the Atlantic Ocean off the coast of Namibia in southwestern Africa. Compared to other bacteria, that would be equivalent to a whale more than a mile long.

H.N. Schulz of the Max Planck Institute for Marine Microbiology in Germany reported finding a new species that approached the enormous size (for bacteria) of a period (like the one at the end of this sentence). Schulz and her research team were amazed to find the previously unknown giant in samples taken more than 300 feet deep in ocean sediments. "These giant bacteria grow as a string of pearls," they said in Science magazine, "which shine white ... and are large enough to be visible to the naked eye." Yet each individual of the species has only one cell.

The big bacterium was given a big name -- Thiomargarita namibiensis (which means "sulfur pearl of Namibia"). The species belongs to a group known as sulfur bacteria that thrive on sulfur compounds from which they obtain energy. However, whereas some sulfur bacteria require oxygen for the energy conversion process, the giant bacteria live in sediments with little or no oxygen present.

Thiomargarita rely instead on nitrogen compounds. Thiomargarita live in deep waters where both sulfur and nitrogen accumulations can be high, but both elements may not always be abundant at the same time. Hence, the bacteria often store one or the other until suitable levels of both are available. The enormous size of Thiomargarita bacteria is explained as a necessity for storage while the organism waits out periods when either nitrogen or sulfur compounds are in short supply.

The unusually large size of the single cells of Thiomargarita was at first a mystery in itself. For species such as bacteria that do not breathe with lungs or gills, the factor limiting an increase in body size is a phenomenon known as volume to surface ratio. …

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