Denitrifying bacteria

Denitrifying bacteria are a diverse group of bacteria that encompass many different phyla. This group of bacteria, together with denitrifying fungi and archaea, is capable of performing denitrification as part of the nitrogen cycle. They metabolise nitrogenous compounds using various enzymes, turning nitrogen oxides back to nitrogen gas or nitrous oxide. Denitrifying bacteria are a diverse group of bacteria that encompass many different phyla. This group of bacteria, together with denitrifying fungi and archaea, is capable of performing denitrification as part of the nitrogen cycle. They metabolise nitrogenous compounds using various enzymes, turning nitrogen oxides back to nitrogen gas or nitrous oxide. There is a great diversity in bacteria capable of performing denitrification. Members of this group encompass most bacterial phyla and therefore possess a wide variety of physiological traits. Denitrifying bacteria have been identified in over 50 genera with over 125 different species and are estimated to represent 10-15% of bacteria population in water, soil and sediment.Denitrifying include for example several species of Pseudomonas, Alkaligenes , Bacillus and others. The majority of denitrifying bacteria are facultative aerobic heterotrophs that switch from aerobic respiration to denitrification when oxygen as an available terminal electron acceptor (TEA) runs out. This forces the organism to use nitrate to be used as a TEA. Because the diversity of denitrifying bacteria is so large, this group can thrive in a wide range of habitats including some extreme environments such as environments that are highly saline and high in temperature. Aerobic denitrifiers can conduct an aerobic respiratory process in which nitrate is converted gradually to N2 (NO3− →NO2− → NO → N2O → N2 ), using nitrate reductase (Nar or Nao), nitrite reductase (Nir), nitric oxide reductase (Nor), and nitrous oxide reductase (Nos). Phylogenetic analysis revealed that aerobic denitrifiers mainly belong to α-, β- and γ-Proteobacteria. Denitrifying bacteria use denitrification to generate ATP.