Impact of copper on the diversity, abundance and transcription of nitrite and nitrous oxide reductase genes in an urban European estuary

• Published in: FEMS microbiology ecology 2011-08, Vol.77 (2), p.274-284
• Main Authors: Magalhães, Catarina M., Machado, Ana, Matos, Patrícia, Bordalo, Adriano A.
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Bacteria - genetics; Bacteria - metabolism; Biological and medical sciences; Brackish water ecosystems; Cluster Analysis; Copper; Copper - chemistry; copper effect; Denaturing Gradient Gel Electrophoresis; Denitrification; denitrifier diversity; DNA, Bacterial - genetics; Ecology; Estuaries; estuarine sediments; Fundamental and applied biological sciences. Psychology; Geologic Sediments - chemistry; Microbial ecology; Microbiology; nirK and nosZ genes; nirS; Nitrates - analysis; Nitrates - metabolism; Nitric Oxide - analysis; Nitric Oxide - metabolism; Nitrites - analysis; Nitrites - metabolism; Nitrogen dioxide; Nitrous oxide; Nitrous Oxide - analysis; Nitrous Oxide - metabolism; Oxidoreductases - analysis; Oxidoreductases - genetics; Polymerase Chain Reaction; Portugal; Rivers - chemistry; RNA, Ribosomal, 16S - genetics; Sediments; Synecology; Water Pollutants, Chemical - chemistry
• ISSN: 0168-6496; 1574-6941
• DOI: 10.1111/j.1574-6941.2011.01107.x

Abstract In this study, the effects of increasing copper (Cu) concentrations on the denitrification pathway and on the diversity of a denitrifier community and gene expression were evaluated in intertidal sandy sediments of the Douro River estuary (north-west Portugal). The results demonstrated that sediment denitrification rates were highly affected by Cu; almost complete inhibition (85%) of the process was observed in sediments amended with 60 μg Cu g−1 wet wt sediment. Moreover, the addition of Cu stimulated the accumulation of both N2O and NO2− and inhibited the rate of NO3− uptake. Further, the amendment with even the lowest Cu concentration (4 μg Cu g−1 wet wt sediment) yielded a drastic decrease in the abundance of nirK, nirS and nosZ (between 79% and 81%) assessed by means of real-time PCR. In agreement, reverse transcription-PCR–denaturing gradient gel electrophoresis analysis of nirK, nirS and nosZ transcripts showed a progressive decrease in the diversity of the transcription products of these genes with an increase of the Cu concentration.