Session 7

Ammonia resistant microorganisms for efficient and sustainable bio-fertilizer production
Janeth Sanabria, Claudia Rodriguez, Carolina Ospina
Universidad del Valle, Colombia

Increasing use of chemical fertilizers and pesticides cause the loss of natural biological nitrogen fixation in soils. It also limits the success of external bacterial inoculation. The Enrichment of Nitrogen Fixing Bacteria (NFB) from municipal wastewater treatment plants (MWWTP) was achieved at laboratory scale. Tolerance to high salt and ammonia concentration was observed. Four WWTP sludges were exposed to different concentrations of salts (>2dS.m-1) and ammonium (>50 mg.L-1). The analysis of the microbial diversity through pyrosequencing and DGGE techniques after 35 days of treatment, did not show changes in the nitrogen-fixing population. The Genus most representative were Clostridium (46,39%), Fluviicola (11,37%), Epilithonimonas (5,97%), Terrimonas (5,01%), Beijerinckia (4,624%), Riemerella (2,699%), Azospirillum (2,458%), Azomonas (2.130%). NFB, associated with other microorganisms involved in the nitrogen cycle suggest the existence of ecological factors for this resistance. By the first time was evaluated the potential use WWTP sludges as a source of alternative Nitrogen-fixing bacteria diversity, to produce resistant inocula to degraded soils.