Structure and function of the soil microbial community in microhabitats of a heavy metal polluted soil |
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| Authors: | E Kandeler D Tscherko K D Bruce M Stemmer P J Hobbs R D Bardgett W Amelung |
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| Institution: | (1) Institute of Soil Science, University of Hohenheim, Emil-Wolff-Strasse 27, 70599 Stuttgart, Germany e-mail: kandeler@uni-hohenheim.de Tel.: +49-711-4594220 Fax: +49-711-4593117, DE;(2) Division of Life Sciences, Franklin-Wilkins Building, 150 Stamford Street, King's College London, London SE1 8WA, UK, GB;(3) Institute of Soil Science, University of Agriculture, Gregor-Mendel-Strasse 33, 1180 Vienna, Austria, AT;(4) Institute of Grassland and Environmental Research, North Wyke Research Station, Okehampton, Devon EX2O 25B, UK, GB;(5) Institute of Environmental and Natural Sciences, Department of Biological Sciences, Lancaster University, Lancaster LA1 4YQ, UK, GB;(6) Institute of Soil Science, University of Bayreuth, 95440 Bayreuth, Germany, DE |
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| Abstract: | Particle-size fractionation of a heavy metal polluted soil was performed to study the influence of environmental pollution
on microbial community structure, microbial biomass, microbial residues and enzyme activities in microhabitats of a Calcaric
Phaeocem. In 1987, the soil was experimentally contaminated with four heavy metal loads: (1) uncontaminated controls; (2)
light (300 ppm Zn, 100 ppm Cu, 50 ppm Ni, 50 ppm V and 3 ppm Cd); (3) medium; and (4) heavy pollution (two- and threefold
the light load, respectively). After 10 years of exposure, the highest concentrations of microbial ninhydrin-reactive nitrogen
were found in the clay (2–0.1 μm) and silt fractions (63–2 μm), and the lowest were found in the coarse sand fraction (2,000–250 μm).
The phospholipid fatty acid analyses (PLFA) and denaturing gradient gel electrophoresis (DGGE) separation of 16S rRNA gene
fragments revealed that the microbial biomass within the clay fraction was predominantly due to soil bacteria. In contrast,
a high percentage of fungal-derived PLFA 18 : 2ω6 was found in the coarse sand fraction. Bacterial residues such as muramic
acid accumulated in the finer fractions in relation to fungal residues. The fractions also differed with respect to substrate
utilization: Urease was located mainly in the <2 μm fraction, alkaline phosphatase and arylsulfatase in the 2–63 μm fraction,
and xylanase activity was equally distributed in all fractions. Heavy metal pollution significantly decreased the concentration
of ninhydrin-reactive nitrogen of soil microorganisms in the silt and clay fraction and thus in the bulk soil. Soil enzyme
activity was reduced significantly in all fractions subjected to heavy metal pollution in the order arylsulfatase >phosphatase
>urease >xylanase. Heavy metal pollution did not markedly change the similarity pattern of the DGGE profiles and amino sugar
concentrations. Therefore, microbial biomass and enzyme activities seem to be more sensitive than 16S rRNA gene fragments
and microbial amino-sugar-N to heavy metal treatment.
Received: 21 January 2000 |
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| Keywords: | Soil microbial biomass Soil enzymes Particle-size fractions Heavy metals Phospholipid fatty acids |
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