Description and Significances
Nitrosococcus oceani is is a marine, gram-negative, chemolithoautotrophic, ammonia-oxidizing bacterium (AOB). Its main source of energy is from oxidizing ammonia. In return the cells release nitrogen and nitrogen oxide. Each cell can produce up to 2x10-6microM of NO2- /day (Watson 1962). It was the first nitrifying bacteria isolated from open ocean water by Watson in 1962. At the time it was known as Nitrosocystis oceanus. N.oceani is able to form cysts and zoogloea in harsh conditions. However, when its genome was completely sequence, little of its genome contributes to tolerate difficult environments (Klotz 2006). It was found in marine world. It was found in Pacific Ocean, and Atlantic Ocean. Oddly, it was found it also to be in the saline waters of Lake Bonney while using FISH for detection. It is widely distributed (Ward 2002). However, within the marine ammonia-oxidizing bacteria, it is dominant by betaproteobacteria (Nold 2000). Nold has used primers, which are complementary to the conservative region of amo and pmo gene, to detect the existence of both gammaproteobacteria and betaproteobacteria in marine water samples collected through out the world. It genome has been completely sequence by Klotz in 2006. In the ocean, it is a frequent target for bacterriophage.
While betaproteobacterial nitrifer has one rrn operon, N.oceani contains two complete sets of rrn operons. However, only one copy of the operon is required. Its genome encodes twenty aminoacyl-tRNA synthetases. It also encodes for two forms of LysRS and two distinct forms of GlxRS but AsnRS and GlnRS are not found. Found to have several sodium/hydrogen antiporters which plays an important role in maintaining intracellular pH allowing it to survive in high salt environment (Klotz 2006).
Its significances are that N. oceani has both nitrification and denitrification activities. It contributes significantly in denitrifying the toxic ammonium, a waste product of animals and plants, into nitrate releasing back into the atmosphere as a resource for plants to grow on. It also could denitrify NO3- back into N2 green gas. (4)