Ponente Invitado: 

Prof. Frank Löffler
Center for Environmental Biotechnology
Department of Microbiology, Department of Civil & Environmental Engineering
The University of Tennessee
Biosciences Division, Oak Ridge National Laboratory
Fecha:  6 de Octubre - 11:00 am
Salones: LL 206

El Centro de Investigaciones en Ingeniería Ambiental de la Universidad de los Andes (CIIA) tiene el gusto de invitarlos a la presentación titulada "Losing Control Over Nitrogen: Nitrous Oxide Emissions on the Rise" a cargo del Profesor Frank Löffler  de la Universidad de Tennessee, Knoxville.

Esta presentación será en inglés.


The invention by Haber and Bosch to produce ammonium fertilizer from nitrogen and hydrogen revolutionized agricultural production and enabled the human population to reach 7 billion.  The Haber-Bosch process introduces about 100 Tg of reactive N per year into the environment worldwide as fertilizer, and the N cycle has been more perturbed than any other basic element cycle.  The unprecedented fertilizer input has major environmental consequences including elevated nitrate concentrations in drinking water and increased emissions of nitrous oxide (N2O), a potent greenhouse gas with ozone destruction potential.  The turnover of nitrogenous compounds in terrestrial and aqueous environments is almost entirely controlled by microbes, and their activities determine N2O fluxes.  While a variety of microbial processes contribute to N2O formation, the only known N2O consumption reaction involves N2O reductase (NosZ).  The canonical clade I-type N2O reductase of denitrifiers has been characterized but recent work discovered novel N2O reductases, which substantially expanded the diversity of this enzyme system.  Metagenomic surveys demonstrated that the novel clade II N2O reductases outnumber their clade I counterparts in the majority of soils.  Growth experiments with organisms harboring the different types of N2O reductase genes demonstrated that bacteria expressing clade II NosZ have significantly higher affinities to N2O suggesting they control N2O emissions to the atmosphere.  Detailed knowledge of the microbial groups controlling N2O consumption under environmentally relevant conditions may provide opportunities to curb N2O emissions from relevant soil ecosystems.