PAH removal of high molecular weight by characterized bacterial strains from different organic sources

This study analyzes the capacity of native bacteria associated with humic acids (HA), sugar cane bagasse (SCB), vermicompost (VC) and the earthworm Eisenia andrei (EaW), to remove polycyclic aromatic hydrocarbons of high molecular weight (HMW-PAH). Bacteria isolation was carried out previous enrichment of the organic sources (OS) with mineral salts and kerosene. An average of 25 bacteria were isolated from each OS and their capacity to remove the PAH, per group (each added at 0.5 O.D), was tested according to a combinatory experimental design with two controls: enriched and non-enriched supernatants of the OS. The bacterial mixture provided by the HA and SCB (44) showed the best performance for degrading the selected PAH. Isolated bacteria associated to these materials were classified into 12 genera, three of which have been previously reported as highly efficient hydrocarbon degraders: Gordonia, Mycobacterium, and Rhodococcus. Regarding the other bacterial genera found, they possess interesting characteristics which include efficient surfactant production capacity, tolerance to high metal concentrations and capacity to reproduce in dry and nutrient-deficient conditions. Therefore, given the characteristics of the isolated hydrocarbonoclastic strains, they could be successfully applied to bioremediation by bioaugmentation of soil co-contaminated with hydrocarbons, metals and even pesticides.