Effect of Triton X-100 and rhamnolipid PS-17 on the mineralization of phenanthrene by Pseudomonas sp. cells

The aim of this study was to investigate the effect of synthetic surfactant Triton X-100 and the rhamnolipid PS-17 biosurfactant on phenanthrene degradation by growing and resting cells of Pseudomonas sp. isolated from active sludge of wastewater treatment plant. Experimental results showed the priority of resting bacterial cells in the biodegradation process over the growing cells. The effect of surfactant concentrations and permeabilization time on the phenanthrene mineralization rate was evaluated. Both the surfactants showed minimal effect on growing culture. The addition of Triton X-100 to the reaction medium of the resting cells inhibited the phenanthrene mineralization, while rhamnolipid PS-17 had no effect on the process. The resting cells permeabilized with Triton X-100 accelerated the initial rate of the biodegradation, while the cells permeabilized with rhamnolipid degraded phenanthrene slower compared with the untreated resting cells. The use of resting cells is an efficient and an inexpensive procedure but took longer time while permeabilized resting cells are efficient in the beginning of the process of phenanthrene biodegradation. The application of resting cells with high degrading activity as well as resting cells preliminary permeabilized with Triton X-100 based a new and effective approach for bioaugmentation and bioremediation of polluted with phenanthrene and with other polyaromatic hydrocarbons' soils and waters.