title: Haloarchaeal assimilatory nitrate-reducing communities from a saline alkaline soil.
abstract: Assimilatory nitrate reduction (ANR) is a pathway wherein NO(3)(-) is reduced to NH(4)(+), an N species that can be incorporated into the biomass. There is little information about the ANR genes in Archaea and most of the known information has been obtained from cultivable species. In this study, the diversity of the haloarchaeal assimilatory nitrate-reducing community was studied in an extreme saline alkaline soil of the former lake Texcoco (Mexico). Genes coding for the assimilatory nitrate reductase (narB) and the assimilatory nitrite reductase (nirA) were used as functional markers. Primers to amplify and detect partial narB and nirA were designed. The analysis of these amplicons by cloning and sequencing showed that the deduced protein fragments shared >45% identity with other NarB and NirA proteins from Euryarchaeota and <38% identity with other nitrate reductases from Bacteria and Crenarchaeota. Furthermore, these clone sequences were clustered within the class Halobacteria with strong support values in both constructed dendrograms, confirming that desired PCR products were obtained. The metabolic capacity to assimilate nitrate by these haloarchaea seems to be important given that at pH 10 and higher, NH(4)(+) is mostly converted to toxic and volatile NH(3), and NO(3)(-) becomes the preferable N source.
authors: Departamento de Biotecnología y Bioingeniería, GIB Cinvestav, México, D.F., Mexico.
authors: Rocio J
authors: RJ
authors: Alcántara-Hernández
authors: César
authors: C
authors: Valenzuela-Encinas
authors: Francisco J
authors: FJ
authors: Zavala-Díaz de la Serna
authors: Javier
authors: J
authors: Rodriguez-Revilla
authors: Luc
authors: L
authors: Dendooven
authors: Rodolfo
authors: R
authors: Marsch
mesh_terms: D019843:Archaeal Proteins / Q000235:genetics; D044822:Biodiversity; D016000:Cluster Analysis; D017931:DNA Primers / Q000235:genetics; D019641:DNA, Archaeal / Q000737:chemistry / Q000235:genetics; D019605:Euryarchaeota / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D008800:Mexico; D008969:Molecular Sequence Data; D050901:Nitrate Reductase / Q000235:genetics; D009566:Nitrates / Q000378:metabolism*; D009572:Nitrite Reductases / Q000235:genetics; D010084:Oxidation-Reduction; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012988:Soil Microbiology
chemical_list: D019843:Archaeal Proteins; D017931:DNA Primers; D019641:DNA, Archaeal; D009566:Nitrates; D009572:Nitrite Reductases; D050901:Nitrate Reductase