The Application of Biosurfactants in Bioremediation of the Aged Sediment Contaminated with Polychlorinated Biphenyls

Currently, there is a considerable interest on application of bio-based surfactants as an alternative to conventional synthetic ones as well as in bioremediation technologies to decontaminate polluted sites more effectively. The work is focused on the study of the effects of two biosurfactants, non-ionic Saponin and anionic Rhamnolipids R-90 on the biodegradation of Delor 103, the industrial mixture of polychlorinated biphenyls (PCBs) by bioaugmented bacterial strains. The bacterial isolates used in this study were obtained from long-term PCB-contaminated sediments of the industrial waste StraA 3/4 sky canal. Enhanced biodegradation of PCBs by Gram-negative strains Achromobacter xylosoxidans (93%) and Stenotrophomonas maltophilia (66%) was observed with the addition of (bio)surfactants Saponin, Rhamnolipids R-90, and Triton X-100 in defined liquid mineral media. The addition of biosurfactant Saponin and Rhamnolipids R-90 increased the PCB biodegradation (55 and 60%, respectively) in the bioaugmented PCB-contaminated sediment inoculated with bacterial strain A. xylosoxidans as well. Regarding to the inhibitory effect of used (bio)surfactants, the obtained IC50 values confirmed that the non-ionic phytogenic Saponin and synthetic surfactant Triton X-100 had a significantly lower toxicity toward bioluminescence of the standard bacteria Vibrio fischeri and used PCB-degrading bacterial strains than the anionic bacterial surfactant Rhamnolipids R-90.