Successful genetic bioaugmentation with Pseudomonas putida for toluene degradation in soil columns

Abstract

There is a strong need for effective and sustainable treatment methods for remediating soils and waters contaminated by fossil fuel pollutants such as aromatic hydrocarbons. Remediation could be improved by genetic bioaugmentation that uses conjugation of catabolic plasmids between bacteria. Research on the conditions for success, effectiveness, and long-term impact of genetic bioaugmentation are therefore necessary. Here the effects of genetic bioaugmentation with Pseudomonas putida BBC 443 was studied in continuous-flow soil columns with or without glucose amendment. Results show that the highest transconjugant occurrence of 21.7 ± 2.1 %, and development of microbial communities with the highest overall toluene degradation potential of 0.0790 ± 0.0055 mg toluene/g soil/h, were achieved in soil columns that received a continuous addition of 1 g/L glucose. Plasmid transfer and toluene biodegradation did not depend on the survival of donor P. putida BBC443, suggesting that genetic bioaugmentation was successful. Furthermore, bacterial community structure analysis revealed that genetic bioaugmentation had limited long-term impact on the soil bacterial community structures, regardless of the specific treatment. Our findings show that genetic bioaugmentation was successful and resulted in limited long-term ecological impact, thus demonstrating that genetic bioaugmentation can provide an effective and sustainable method for in situ bioremediation.