Environmental factors associated with heterotrophic nitrogen-fixing bacteria in water, sediment and riparian soil of Suquía River

MERLO CAROLINA; REYNA LUCIANA; ABRIL ADRIANA; AMÉ VALERIA; GENTI DE RAIMONDI SUSANA

LIMNOLOGICA

ELSEVIER GMBH

Año: 2014 vol. 48 p. 71 - 71

0075-9511

n this study we investigated the environmental factors associated with biological nitroge (N) fixation (BNF) in water, sediments, and riparian soil along a polluted river (Suquía River of Córdoba, Argentina). Here, we screened heterotrophic nitrogen-fixing bacteria and assessed the magnitude of BNF at different sites of Suquía River. To this aim, samples of the three habitats (riparian soil, water, and sediment) were collected from five polluted sites and one reference site during low and high flow water periods. In all samples the abundance of N-fixing bacteria was evaluated in solid nitrogen-free medium and the biological N fixation was measured by nitrogenase (Nase) enzyme activity using the acetylene reduction method. To identify the heterotrophic N-fixing taxa DNA of nine cultures isolated from sites with different Nase enzyme activity was extracted and the 16S rRNA gene was amplified and sequenced. In addition, the ammonia and organic carbon (C) content in all samples, the disso