Thiomargarita namibiensis is a gram-negative, facultative anaerobic, coccoid bacterium found in South America's ocean sediments of the continental shelf of Namibia.

Thiomargarita namibiensis is categorized as a mesophile[6] because it prefers moderate temperatures, which typically range between 20-45 degrees Celsius.

[7] The species Thiomargarita namibiensis was collected in 1997 and discovered in 1999 by Heide N. Schulz and her colleagues from the Max Planck Institute for Marine Microbiology.

[9][4] Researchers suggested the species be named Thiomargarita namibiensis, which means "sulfur pearl of Namibia", which was fitting as the bacteria appeared a blue-green, white color, as well as spheres strung together.

[9][11] In 2002 a strain exhibiting 99% identity with Thiomargarita namibiensis was found in sediment cores taken from the Gulf of Mexico during a research expedition.

[14] Thiomargarita namibiensis is most prevalent in the Walvis Bay area at 300 feet deep,[15] but they are distributed along the coast of Namibia from Palgrave Point to Lüderitzbucht.

[18] Here, Thiomargarita namibiensis is easily suspended in moving ocean currents due to the sheath around the cells, which makes it easy for the bacteria to passively float.

T. namibiensis is more prevalent in areas with free gas, suggesting that the presence of suspended sulfide is beneficial to the bacteria.

The Namibian coastal environmental experiences strong upwelling, resulting in low oxygen levels with large amounts of plankton.

The lower waters lack oxygen due to the multitude of microorganisms releasing carbon dioxide while they perform heterotrophic respiration to generate energy.

[22] Internal polyphosphate and nitrate are used as external electron acceptors in the presence of acetate, releasing enough phosphate to cause precipitation.

[23] The Mexican strain was primarily found in the top centimeter of sediment sampled from cold seeps in the Gulf of Mexico.

[24] In contrast, Thiomargarita grow in rows of separate single spherical cells, so they lack the range of motility that Thioploca and Beggiota have.

T. namibiensis holds the record for the world's second largest bacterium, with a volume three million times more than that of average bacteria.

[29] With their lack of movement, Thiomargarita have adapted by evolving the very large nitrate-storing bubbles vacuoles, allowing them to survive long periods of nitrate and sulfide starvation.

[31] Other large sulfur bacteria found in the same sediment samples as T. namibiensis with different structures, such as Thioploca and Beggiota, have gliding motility.

The vacuoles of Thiomargarita namibiensis contribute to their gigantism, allowing them to store nutrients for asexual reproduction of their complex genome.

The smaller the size of a cell, the quicker it can reproduce and diffuse nutrients, and the higher the likelihood the biomolecule will almost immediately reach its site of activity.

[35] T. namibiensis can perform normal diffusion due to the reduced amount of cytoplasm as a result of its large vacuoles.

[3] The storage capacity of these vacuoles can allow T. namibiensis cells to survive for prolonged lengths of time without access to nutrients.

[7] This adaptation shows how the bacterium has learned to survive in specific environments where usual metabolic pathways might not work well enough.

[37] However, this bacterium is predominantly located in environments of very minimal to no oxygen availability; therefore, nitrate will be the standard electron acceptor for the oxidation-reduction reaction.

[37] While sulfide is available in the surrounding sediment, produced by other bacteria from dead microalgae that sank down to the sea bottom, the nitrate comes from the above seawater.

[41] Thiomargarita namibiensis has an ability to survive in nutrient-poor environments due to stored nitrate and sulfur, which enables the cells to stay alive without reproducing.

[39] Reproduction of T. namibiensis occurs on a single plane; the cocci (a spherical bacterial cell) divide into a diplococcus or streptococcus arrangement.

In addition to helping with essential functions including food exchange and cell-to-cell communication, this matrix can give the bacteria protection and structural support.

This peripheral design provides efficient cellular activities by lowering the distance over which chemical signals and metabolites must travel despite the huge cell volume.

[47][48] This genetic redundancy helped its metabolic requirements and improved its capacity to repair damaged DNA by environmental stresses.

T. namibiensis is found in sulfide-rich, oxygen-poor marine sediments because of its gene involved in sulfur oxidation and nitrate reduction.

T. namibiensis can release phosphate in anoxic sediments at high rates which contribute to the spontaneous precipitation of phosphorus-containing material.