title: Sheep-urine-induced changes in soil microbial community structure.
abstract: Soil microbial communities play an important role in nutrient cycling and nutrient availability, especially in unimproved soils. In grazed pastures, sheep urine causes local changes in nutrient concentration which may be a source of heterogeneity in microbial community structure. In the present study, we investigated the effects of synthetic urine on soil microbial community structure, using physiological (community level physiological profiling, CLPP), biochemical (phospholipid fatty acid analysis, PLFA) and molecular (denaturing gradient gel electrophoresis, DGGE) fingerprinting methods. PLFA data suggested that synthetic urine treatment had no significant effect on total microbial (total PLFA), total bacterial or fungal biomass; however, significant changes in microbial community structure were observed with both PLFA and DGGE data. PLFA data suggested that synthetic urine induced a shift towards communities with higher concentrations of branched fatty acids. DGGE banding patterns derived from control and treated soils differed, due to a higher proportion of DNA sequences migrating only to the upper regions of the gel in synthetic urine-treated samples. The shifts in community structure measured by PLFA and DGGE were significantly correlated with one another, suggesting that both datasets reflected the same changes in microbial communities. Synthetic urine treatment preferentially stimulated the use of rhizosphere-C in sole-carbon-source utilisation profiles. The changes caused by synthetic urine addition accounted for only 10-15% of the total variability in community structure, suggesting that overall microbial community structure was reasonably stable and that changes were confined to a small proportion of the communities.
authors.affiliation: Biomathematics and Statistics Scotland, Scottish Crop Research Institute, Dundee, UK. nunan@grignon.inra.fr
authors.forename: Naoise
authors.initials: N
authors.lastname: Nunan
authors.forename: Brajesh
authors.initials: B
authors.lastname: Singh
authors.forename: Eileen
authors.initials: E
authors.lastname: Reid
authors.forename: Brian
authors.initials: B
authors.lastname: Ord
authors.forename: Artemis
authors.initials: A
authors.lastname: Papert
authors.forename: Julie
authors.initials: J
authors.lastname: Squires
authors.forename: Jim I
authors.initials: JI
authors.lastname: Prosser
authors.forename: Ron E
authors.initials: RE
authors.lastname: Wheatley
authors.forename: Jim
authors.initials: J
authors.lastname: McNicol
authors.forename: Peter
authors.initials: P
authors.lastname: Millard
mesh_terms: D000818:Animals; D001419:Bacteria / Q000145:classification / Q000235:genetics; D018533:Biomass; D002244:Carbon / Q000378:metabolism; D015169:Colony Count, Microbial; D017753:Ecosystem; D004586:Electrophoresis; D005227:Fatty Acids / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D010743:Phospholipids / Q000378:metabolism; D012756:Sheep / Q000652:urine*; D012988:Soil Microbiology; D014556:Urine / Q000502:physiology
chemical_list: D005227:Fatty Acids; D010743:Phospholipids; D002244:Carbon