Effects of multiple bacterial species and nutrient injection on phenanthrene transport and bacterial cell elution

Abstract

The objectives of this study were to investigate the effects of multiple bacterial species and nutrient injection on phenanthrene degradation, cell elution, and cell distribution within a column system. Three indigenous, phenanthrene degrading species, Actinobacter junii, Pseudamonas oleovorans, and Methylbacterium sp., were used. Characterization studies were conducted to determine the relative cell yield and cell hydrophobicity. Transport studies were conducted in a saturated column system. Results show single bacterial species produce relatively stable cell elution and phenanthrene biodegradation curves. In addition, it appears that cell density within the column may be dependent on cell hydrophobicity and possibly column carrying capacity. Conversely, phenanthrene degradation and cell elution was variable in the presence of multiple bacterial species. Results indicate that synergistic and antagonistic interactions occurred among the species. Injection of an alternative carbon source (R2B) enhanced phenanthrene degradation only in the single species column containing Actinobacter junii. It caused increased cell elution in Actinobacter junii and Pseudamonas oleovorans single species columns. No increase in degradation was found in multi-species columns injected with R2B. These studies illustrate that the dynamics of complex microbial communities should be considered when evaluating contaminant biodegradation and transport in subsurface systems. The findings presented here have important implications for representation of biodegradation in computer modeling and in the design of bioremediation strategies.