Bioaugmentation effect of Absidia cylindrospora on a PAHs and trace metals co-contaminated soil within a 3-month microcosm-experiment

Soil contamination is becoming a major concern due to the rapid urbanization and industrialization. The urgency to clean contaminated sites using biological methods becomes important. This paper presents for the first time the bioaugmentation effect of the fungal strain Absidia cylindrospora on a co-contaminated industrial soil. The tests were carried out in real industrial soil microcosms with varying incubation times. The study focuses on the evolution over time of the metals and PAHs content in the soil, as well as on the adsorption and/or accumulation of metals within the mycelium of Absidia cylindrospora. Even if metal contamination remained stable in the soil over 3 months, Absidia cylindrospora demonstrated its ability to simultaneously accumulate Cd, Co, Cu, Ni and Zn even in the presence of high concentrations of PAHs. The study revealed that the biosorption of Cr on the mycelium was stable during the test period whereas the bioaccumulation of the other metals (Cd, Co, Cu, Ni and Zn) within the mycelium increased with the aging of the mycelium. The ability of the fungal strain to accumulate metals appeared to correlate with the levels of the initial soil concentrations and their environmental availability, estimated by single HCl extraction. The effect of this strain on the dissipation of PAHs in the soil containing high concentrations of metals was more difficult to assess. An increase in PAH availability was first observed, measured by a concentration increase in the soil, followed by a dissipation trend only after 2 months.