Soil microbial communities: Influence of geographic location and hydrocarbon pollutants

The importance and relevance of the geographical origin of the soil sample and the hydrocarbons in determining the functional or species diversity within different bacterial communities was evaluated using the community level physiological profiles (CLPP) and Polymerase Chain Reaction–Denaturing Gradient Gel Electrophoresis (PCR-DGGE). Hydrocarbon contaminated and uncontaminated soils from different geographical locations were used in the study. In addition, the influence or relevance of the geographical location of the sample was further evaluated by artificially contaminating soils from different geographical locations with different petroleum products. The hydrocarbons rather than the geographical origin of the sample appear to be more important in determining functional or species diversity within the bacterial communities. Cluster analysis of the different community profiles using both functional and molecular responses revealed that the samples from different locations were as different as samples from the same location but from contaminated versus uncontaminated soils. The results of the soils from different locations artificially contaminated by different hydrocarbons also reached the same conclusion. The samples from different soils were as different as samples from the same soil contaminated by different petroleum products. In addition, the removal rate of the different hydrocarbons in the artificially contaminated soil was different. The results suggest that the pollutants rather than the geographical origin of the sample might be more important in determining the functional or species diversity within bacterial communities.