title: NO3-/NO2- assimilation in halophilic archaea: physiological analysis, nasA and nasD expressions.
abstract: The haloarchaeon Haloferax mediterranei is able to assimilate nitrate or nitrite using the assimilatory nitrate pathway. An assimilatory nitrate reductase (Nas) and an assimilatory nitrite reductase (NiR) catalyze the first and second reactions, respectively. The genes involved in this process are transcribed as two messengers, one polycistronic (nasABC; nasA encodes Nas) and one monocistronic (nasD; codes for NiR). Here we report the Hfx mediterranei growth as well as the Nas and NiR activities in presence of high nitrate, nitrite and salt concentrations, using different approaches such as physiological experiments and enzymatic activities assays. The nasA and nasD expression profiles are also analysed by real-time quantitative PCR. The results presented reveal that the assimilatory nitrate/nitrite pathway in Hfx mediterranei takes place even if the salt concentration is higher than those usually present in the environments where this microorganism inhabits. This haloarchaeon grows in presence of 2 M nitrate or 50 mM nitrite, which are the highest nitrate and nitrite concentrations described from a prokaryotic microorganism. Therefore, it could be attractive for bioremediation applications in sewage plants where high salt, nitrate and nitrite concentrations are detected in wastewaters and brines.
authors: División de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de Alicante, Ap. 99, 03080, Alicante, Spain.
authors: Rosa María
authors: RM
authors: Martínez-Espinosa
authors: Belén
authors: B
authors: Lledó
authors: Frutos C
authors: FC
authors: Marhuenda-Egea
authors: Susana
authors: S
authors: Díaz
authors: María José
authors: MJ
authors: Bonete
mesh_terms: D019843:Archaeal Proteins / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D019641:DNA, Archaeal / Q000235:genetics; D015870:Gene Expression; D019766:Genes, Archaeal; D019623:Haloferax mediterranei / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D050901:Nitrate Reductase / Q000235:genetics* / Q000378:metabolism*; D009566:Nitrates / Q000378:metabolism; D009572:Nitrite Reductases / Q000235:genetics* / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism; D054712:Salinity
chemical_list: D019843:Archaeal Proteins; D017931:DNA Primers; D019641:DNA, Archaeal; D009566:Nitrates; D009573:Nitrites; D009572:Nitrite Reductases; D050901:Nitrate Reductase