Quantification of a novel narG community in sediments of Suquía River basin along a nitrate gradient.

REYNA LUCIANA; WUNDERLIN DANIEL; GENTI-RAIMONDI SUSANA

San Miguel de Tucumán, Tucumán

Congreso; XLV Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2009

Saib

We evaluated the molecular diversity of narG gene from sediments of Suquía River basin, which is affected by anthropogenic pollution, to assess the impact of nitrate concentration on the composition and structure of the nitrate-reducing bacterial community. To this aim, a library of one of the six monitoring stations corresponding to the highest nitrate concentration was constructed and 118 narG clones were screened. Nucleotide sequences were associated to narG gene from a-, b-, d-, g- proteobacteria and Thermus thermophilus. Remarkably, 18% of analyzed clones encode NarG sequences with less than 69% similarity to NarG sequences available in databases. Thus, pointing out the presence of nitrate-reducing bacteria with novel sequences, which were quantified by qPCR. Results show a variable number of narG copies, ranging from undetectable to 5.0 x 104 copies per ng DNA or to 0.05 narG/16S rDNA ratio, in correspondence with the nitrate concentration and water quality index monitored along the basin at different times. Thus, bacterial biodiversity is also affected by the nitrate gradient produced by anthropogenic activities. Supported by CONICET, FONCyT and SECyT-UNC.