Microbial community DNA was extracted directly from an arable soil experimentally polluted with Cd, Cu, Ni, Pb or Zn, and incubated for 34 months. Broad-scale measurements of changes in microbial community structure were assessed by applying %G+C profiling and community hybridisation techniques to the DNA, and compared with phospholipid fatty acid (PLFA) profiles. %G+C profiles, statistically compared using parameterisation and principal component analysis, differed between treatments. Community hybridisation revealed a range of DNA similarities between treatments. The combination of these two techniques facilitated the interpretation of the data. The differences between the treatments determined by DNA analysis were consistent with the PLFA patterns, and revealed that: (i) microbial communities in metal contaminated soils were different from those in uncontaminated soil, (ii) the microbial community in Cu contaminated soil was different from those in soils contaminated with the other metals, and (iii) the microbial communities in soils contaminated with Pb and Ni were indistinguishable from one another.
