Functional and community-level soil microbial responses to zinc addition may depend on test system biocomplexity

• Published in: Chemosphere (Oxford) 2006-12, Vol.65 (10), p.1747-1754
• Main Authors: Sverdrup, Line E., Linjordet, Roar, Strømman, Gjermund, Hagen, Snorre B., van Gestel, Cornelis A.M., Frostegård, Åsa, Sørheim, Roald
• Format: Article
• Language: English
• Subjects: Analysis of Variance; Animal, plant and microbial ecology; Animals; application rate; Applied ecology; bioavailability; Biological and medical sciences; biomarkers; Biomass; Dose-Response Relationship, Drug; earthworms; ecological function; Ecosystem; Ecotoxicology, biological effects of pollution; Eisenia fetida; Fatty Acids - analysis; Fatty Acids - metabolism; forage crops; forage grasses; Fundamental and applied biological sciences. Psychology; General aspects; heavy metals; Lolium - drug effects; Lolium multiflorum; microbial activity; Microbial ecology; Model ecosystem; Multispecies; nitrification; Nitrites - metabolism; Oligochaeta - drug effects; Oligochaeta - growth & development; Phospholipids - chemistry; Phospholipids - metabolism; Quaternary Ammonium Compounds - metabolism; soil fertility; Soil Microbiology; soil microorganisms; species diversity; Terrestrial; toxicity; Various environments (extraatmospheric space, air, water); zinc; Zinc - pharmacology; zinc fertilizers
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2006.04.075

The effect of zinc on soil nitrification and composition of the microbial community in soil was investigated using a full factorial experiment with five zinc concentrations and four levels of biological complexity (microbes only, microbes and earthworms ( Eisenia fetida), microbes and Italian ryegrass ( Lolium multiflorum var. Macho), and microbes, ryegrass and earthworms). After 6 weeks of exposure, the activity of soil nitrifying bacteria was measured and the microbial community structure was characterized by phospholipid fatty acid (PLFA) analysis. Soil nitrification and several PLFA markers were significantly influenced by either zinc addition and/or the presence of earthworms or ryegrass, and one of the most pronounced changes was the increase of fungi and decrease of bacteria with increasing concentrations of zinc. Of particular interest, however, was the potential interaction between the presence of plants and/or earthworms and the effect of zinc, which the factorial study design allowed us to explore. Such an effect was observed in two cases: Earthworms reduced the positive effect of zinc on the fungal biomass (ANOVA, p = 0.03), and the effect of earthworms on the soil nitrification activity depended on zinc concentration (ANOVA, p < 0.05). The effect of earthworm presence was not very large, but it does show that multispecies tests might give information about metal toxicity or bioavailability that cannot be predicted from single-species tests.