Clostridium sticklandii
| Clostridium sticklandii | |
|---|---|
| Scientific classification | |
| Kingdom: | Bacteria |
| Division: | Firmicutes |
| Class: | Clostridia |
| Family: | Clostridiaceae |
| Genus: | Clostridium |
| Species: | Cl. sticklandii |
| Binomial name | |
|
Clostridium sticklandii Stadtman and McClung 1957 (Approved Lists 1980) |
|
Clostridium sticklandii is an anaerobic, motile, gram-positive bacterium. It was first isolated in 1954 from the black mud of the San Francisco Bay Area by T.C. Stadtman, who also named the species.Cl. sticklandii is not pathogenic in humans.
Cl. sticklandii ferment amino acids by using the Stickland reaction, which couples the oxidation of one amino acid and the reduction of another. L.H. Stickland described this process in 1934. The enzymes in the Stickland reaction are D-proline reductase (an elecron acceptor) and Glycine reductase. Cl. sticklandii preferentially utilize threonine, arginine, serine, cysteine, proline, and glycine during the growth phase and lysine during the stationary phase, while excreting glutamate, aspartate and alanine.
Selenoproteins can be found in the genome of Cl. sticklandii. One such selenoprotein, glycine reductase A was first identified in Cl. sticklandii. C. sticklandii uses a total of eight of these selenoproteins. One of which, PrdC, was not previously thought to be a selenoprotein. PrdC, which is similar to RnfC in other species, is found within the D-proline reductase operon. The D-proline reductase operon is responsible for the reductive ring cleavage of D-proline into 5-aminovalerate. 5-aminovalerate is excreted by Cl. sticklandii.
Although energy conservation in Cl. sticklandii is achieved through substrate level phosphorylation, it can be achieved via electron-transport phosphorylation as well. The Rnf complex, a Na+-dependent F-ATPase, V-ATPase, and a membrane-bound Pyrophosphatase serve as methods to conserve energy through electron-transport phosphorylation.
On another interesting note, Cl. sticklandii have two carbon dioxide fixation pathways, Wood-Ljundgahl and Glycine synthase/glycine reductase pathways. It is an oddity to find both of these methods of carbon dioxide fixation simultaneously. Only four other bacterial species have been observed to contain both of these pathways. Although, Cl. sticklandii has the ability to utilize both pathways, it has not been determined if they do utilize both pathways at the same time.
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