Characterization and comparison of potential denitrifiers in microbial mats from King George Island, Maritime Antarctica

• Published in: Polar biology 2014-03, Vol.37 (3), p.403-416
• Main Authors: Alcántara-Hernández, Rocio J., Centeno, Carla M., Ponce-Mendoza, Alejandro, Batista, Silvia, Merino-Ibarra, Martin, Campo, Julio, Falcón, Luisa I.
• Format: Article
• Language: English
• Subjects: Air pollution; Analysis; Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Biomedical and Life Sciences; Cyanobacteria; Denitrification; Ecology; Enzymes; Ethylenediaminetetraacetic acid; Fundamental and applied biological sciences. Psychology; Greenhouse gases; Inland waters; Life Sciences; Microbiology; Microorganisms; Nitrogen oxide; Nitrous oxide; Nutrient dynamics; Nutrient loss; Nutrients; Oceanography; Original Paper; Ozone depletion; Ozone layer depletion; Particular ecosystems; Plant Sciences; Sediments (Geology); Streams; Synecology; Water column; Zoology
• ISSN: 0722-4060; 1432-2056
• DOI: 10.1007/s00300-013-1440-3

Cyanobacterial microbial mats are highly structured communities commonly found in Antarctic inland waters including melt streams. These benthic microbial associations comprise a large number of microorganisms with different metabolic capacities, impacting nutrient dynamics where established. The denitrification process is a feasible nitrogen loss pathway and a biological source of nitrous oxide, a potent greenhouse gas that also promotes ozone depletion. Potential denitrifiers from five microbial mats were characterized using a PCR-DGGE (denaturing gradient gel electrophoresis) approach. Molecular markers encoding for key enzymes in the denitrification process ( nir K, nir S and nos Z) were used. Fingerprints were obtained for the five sampled mats and compared for two successive years. Distance analysis showed that despite the sampled year, the denitrifying genetic potential was similar between most of the sites when represented in Euclidean space. The number of dominant denitrifiers detected for each sample ranged between 6 and 18 for nir K, 4–10 for nir S and 6–17 for nos Z. The seventy-two sequenced phylotypes showed 80–98 % identity to previously reported environmental sequences from water column, sediments and soil samples. These results suggest that Antarctic microbial mats have a large denitrification potential, previously uncharacterized and composed by both site-specific and common phylotypes belonging mainly to Alpha -, Beta - and Gammaproteobacteria .