The influence of synthetic sheep urine on ammonia oxidizing bacterial communities in grassland soil

Shahid Mahmood, James Ivor Prosser

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

In grazed, grassland soils, sheep urine generates heterogeneity in ammonia concentrations, with potential impact on ammonia oxidizer community structure and soil N cycling. The influence of different levels of synthetic sheep urine on ammonia oxidizers was studied in grassland soil microcosms. 'Total' and active ammonia oxidizers were distinguished by comparing denaturing gradient gel electrophoresis (DGGE) profiles following PCR and RT-PCR amplification of 16S rRNA gene fragments, targeting DNA and RNA, respectively. The RNA-based approach indicated earlier, more reproducible and finer scale qualitative shifts in ammonia oxidizing communities than DNA-based analysis, but led to amplification of a small number of nonammonia oxidizer sequences. Qualitative changes in RNA-derived DGGE profiles were related to changes in nitrate accumulation. Sequence analysis of excised DGGE bands revealed that ammonia oxidizing communities in synthetic sheep urine-treated soils consisted mainly of Nitrosospira clusters 2, 3 and 4. Nitrosospira cluster 2 increased in relative abundance in microcosms treated with all levels of synthetic sheep urine. Low levels additionally led to increased relative abundance of Nitrosospira cluster 4 and medium and high levels increased relative abundance of cluster 3. Synthetic sheep urine is therefore likely to influence the spatial distribution and composition of ammonia oxidizer communities, with consequent effects on nitrate accumulation.

Original languageEnglish
Pages (from-to)444-454
Number of pages10
JournalFEMS Microbiology Ecology
Volume56
DOIs
Publication statusPublished - 2006

Keywords

  • 16S rRNA gene
  • denaturing gradient gel electrophoresis
  • ammonia oxidizing bacteria
  • grassland soil
  • sheep urine
  • GRADIENT GEL-ELECTROPHORESIS
  • 16S RIBOSOMAL-RNA
  • MICROBIAL COMMUNITY
  • FUNCTIONAL DIVERSITY
  • MANAGEMENT REGIMENS
  • MOLECULAR ANALYSIS
  • GENE-SEQUENCES
  • FOREST SOIL
  • NITROGEN
  • DNA

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