Evaluation of the removal of pyrene and fluoranthene by Ochrobactrum anthropi, Fusarium sp. and their coculture.

Fluoranthene and pyrene are polycyclic aromatic hydrocarbons of high molecular weight that are recalcitrant and toxic to humans; therefore, their removal from the environment is crucial. From hydrocarbon-contaminated soil, 25 bacteria and 12 filamentous fungi capable of growth on pyrene and fluoranthene as the sole carbon and energy source were isolated. From these isolates, Ochrobactrum anthropi BPyF3 and Fusarium sp. FPyF1 were selected and identified because they grew quickly and abundantly in both hydrocarbons. Furthermore, O. anthropi BPyF3 and Fusarium sp. FPyF1 were most efficient at removing pyrene (50.39 and 51.32 %, respectively) and fluoranthene (49.85 and 49.36 %, respectively) from an initial concentration of 50 mg L(-1) after 7 days of incubation. Based on this and on the fact that there was no antagonism between the two microorganisms, a coculture composed of O. anthropi BPyF3 and Fusarium sp. FPyF1 was formed to remove fluoranthene and pyrene at an initial concentration of 100 mg L(-1) in a removal kinetic assay during 21 days. Fluoranthene removal by the coculture was higher (87.95 %) compared with removal from the individual cultures (68.95 % for Fusarium sp. FPyF1 and 64.59 % for O. anthropi BPyF3). In contrast, pyrene removal by the coculture (99.68 %) was similar to that obtained by the pure culture of Fusarium sp. FPyF1 (99.75 %). The kinetics of removal for both compounds was adjusted to a first-order model. This work demonstrates that the coculture formed by Fusarium sp. FPyF1 and O. anthropi BPyF3 has greater potential to remove fluoranthene than individual cultures; however, pyrene can be removed efficiently by Fusarium sp. FPyF1 alone.