The Largest Bacterium: Scientist Discovers New Bacterial Life Form Off The Afr...( Even visible to the naked eye new...)

Even visible to the naked eye, newly discovered bacteria named Thiomargarita namibiensis are the largest prokaryotic organisms yet known. Biologist Heide Schulz from the Max Planck Institute for Marine Microbiology in Bremen found these up to 3/4 mm wide microorganisms during a cruise with the Russian research vessel "Petr Kottsov" in sediments off the Namibian coast. The bacteria live from sulfide produced in the sea floor and store nitrate from the seawater in an "anaerobic lung".

It seems rather odd that these bacteria were overlooked so far by marine scientists. During an expedition off the coast of Namibia in the search of other sulfur bacteria known from the pacific coast of South America, biologist Heide Schulz was quite surprised when she looked at her sediment samples more closely. The spherical cells of Thiomargarita namibiensis are generally 0.1 - 0.3 millimeter wide but some reach up to a size of 3/4 of a millimeter. They live in great numbers in the coastal sediments off Walvis Bay (Namibia), and shine white because microscopic sulfur granules, which they store inside, reflect the incident light. Held in line by a common mucus sheath, they look like a thin string of pearls, which inspired the researchers of the Max Planck Institute for Marine Microbiology to name these bacteria Thiomargarita namibiensis, i.e. "Sulfur Pearl of Namibia". Thiomargarita namibiensis has its ecological niche in the oxygen-poor but nutrient-rich sediment and can survive in this environment which is toxic for most animal life due to high levels of hydrogen sulfide.

In cooperation with the director of the institute, professor Bo Barker Jorgensen, biologist Schulz and her colleagues were able to demonstrate how the bacteria are adapted to this special environment. Under the microscope they discovered that almost the entire volume of the cell is a liquid container, a vacuole. This container makes up 98% of the cells internal volume. It is used to store nitrat
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Contact: Heide Schulz
hschulz@mpi-bremen.de
49-421-2028-646
Max-Planck-Gesellschaft
16-Apr-1999