Monitoring the changes in a bacterial community in petroleum-polluted soil bioaugmented with hydrocarbon-degrading strains

Abstract Bioaugmentation is a strategy used to enhance degradation of petroleum compounds in contaminated soils, however little is known about the interactions between introduced bacteria and autochthonous microflora. Therefore the objective of the study was to assess any changes in the structure and metabolic activity of the soil bacterial communities as a result of the introduction of Bacillus subtilis T′-1 or Pseudomonas sp. P-1, as well their consortium, into petroleum-contaminated soil. The bioaugmentation experiment was carried out under laboratory conditions using soil taken from an industrial area located around a refinery in Czechowice-Dziedzice. After the bioaugmentation process, a significant ( P alkB gene copies during 91 days of the study compared to the non-treated soil. Analysis of the 16S rRNA and alkB genes-based DGGE fingerprints showed that introduced bacteria changed the genetic diversity of the total bacterial communities as well as the communities that have the genes involved in the degradation of hydrocarbons. Analysis of the PLFA profiles showed that the bacterial strains caused short-term changes in the amounts of fatty acids characteristic for Gram-positive and Gram-negative bacteria. The CLPPs indicated differences in soil metabolic activity between the inoculated and non-inoculated soils after the bioaugmentation process.