Spatial distribution of N-cycle associated microbial communities and their functional activities showed complex patterns in constructed wetland sediments.

DAVID CORREA-GALEOTE; DIANA MARCO; GERMÁN TORTOSA; DAVID BRU; LAURENT PHILIPPOT; EULOGIO BEDMAR

FEMS MICROBIOLOGY ECOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2012 vol. 83 p. 340 - 351

0168-6496

Constructed wetlands are used for biological treatment of wastewater from agricultural lands carrying pollutants like nitrates. Nitrogen removal in wetlands occurs from direct assimilation by plants and through microbial nitrification and denitrification activities. We investigated the spatial distribution of N-cycling microbial communities and genes involved in nitrification and denitrification in sediments from a constructed wetland receiving irrigation water. We used quantitative real-time PCR (qPCR) to characterize microbial communities and data were analysed using geostatistical variance analysis to relate them with vegetation cover and biogeochemical sediment properties. The spatial distribution of the N-cycling microbial communities of sediments from crop irrigation waters was heterogeneous and complex. Total communities of bacteria and archaea showed different spatial distributions. Analysis of autocorrelation patterns through semivariance and fractal variograms indicated a tendency to a patchy distribution over scales around 10 m for genes involved in the nitrification and denitrification processes. In contrast, biogeochemical properties of the sediments showed more diverse spatial distributions. While almost no patchiness was found for pH and sediment moisture, patchiness at scales between 8 to 10 m was detected for carbon, nitrate and ammonia. Denitrification variables showed spatial autocorrelation at scales comparable to genes. However, denitrifying enzyme activity and potential N2O production showed a common spatial pattern, different from that of the N2O/(N2O + N2) ratio. Spatial distribution of N-cycle associated microbial communities and genes, and their functional activities, showed a complex relationship with wetland sediment properties and environmental variables.