Relating microbial community structure to a dominant environmental variable in a complex environment: An example from a chromium contaminated site

In a complex environment, it can be difficult to assess the degree to which an environmental variable influences microbial community structure. We propose a method that uses the community data to "predict" the value of the presumed dominant variable. The assumption is that in order to "predict" the variable, the community composition must be sensitive to or affected by the variable in question. The concentration range over which the prediction is accurate should thus provide information on the concentrations that influence community structure. We explored this approach using terminal restriction fragment length (T-RFLP) data from a site contaminated by tannery wastes. We were able to use the microbial community structure measures to predict Cr concentration over a surprisingly wide range of concentration. Although it appears from this work that this approach can give useful information about the relationships between microbial community structure and specific environmental conditions further testing is required.