Structural and functional response of soil microbiota to addition of plant substrate are moderated by soil Cu levels

• Published in: Biology and fertility of soils 2010-04, Vol.46 (4), p.333-342
• Main Authors: Wakelin, Steven Alan, Chu, Guixin, Broos, Kris, Clarke, K. R, Liang, Yongchao, McLaughlin, Mike J
• Format: Article
• Language: English
• Subjects: Agriculture; Alfalfa; Biomedical and Life Sciences; Community structure; Copper; Decomposition; Ecological function; Energy transfer; Life Sciences; Medicago truncatula; Nutrient cycles; Original Paper; Soil fertility; Soil microorganisms; Soil Science & Conservation; Soils; Substrates; Trophic relationships
• ISSN: 0178-2762; 1432-0789
• DOI: 10.1007/s00374-009-0436-1

In soils, the microbially mediated decomposition of plant residue is a key process with wide ranging effects on ecosystem functioning and stability. Understanding the impact of contamination on this process is of high importance. We investigated the effects of long-term (6 years) copper exposure on the capacity of soil microbiota to decompose newly added resources; dried and ground Medicago truncatula stubble. In addition, the effects on the microbial community structure across the three domains were explored using polymerase chain reaction-denaturing gradient gel electrophoresis rRNA gene profiling. Ecological distances in community structure between treatments was calculated (Kulczynski) and effects tested using PERMANOVA. Clear dose-response relationships were present between microbial respiration (CO₂ evolution) and soil Cu level in soils receiving medic, but not under basal conditions (i.e., no medic added). These show that relatively labile forms of C are needed to drive microbial ecotoxicological responses and that microbial adaptation to the presence of Cu in the soils—after >6 years exposure—was functionally limited. Bacterial, archaeal and fungal communities showed significant (P