Increase in Total Petroleum Hydrocarbons Removal Rate in Contaminated Mining Soil Through Bioaugmentation with Autochthonous Fungi During the Slow Bioremediation Stage

Hernández-Adame, N. M.; López-Miranda, J.; Martínez-Prado, M. A.; Cisneros-de la Cueva, S.; Rojas-Contreras, J. A.; Medrano-Roldán, H.

Increase in Total Petroleum Hydrocarbons Removal Rate in Contaminated Mining Soil Through Bioaugmentation with Autochthonous Fungi During the Slow Bioremediation Stage

2021

The removal of total petroleum hydrocarbons (TPHs) from contaminated mining soil was carried out under in vitro conditions. The aerobic consumption of TPH in the slow bioremediation stage via biostimulation with native microorganisms and biostimulation-bioaugmentation with autochthonous fungal isolates was evaluated. The initial TPH concentration was 70,880 ± 975 mg TPH/kg soil, soil was amended with nutrients at a C:N:P ratio of 100:15:1, the water content was adjusted to the soil field capacity, and batch microcosm reactors were incubated at room temperature (20.5 ± 3.1°C) for 90 days. The bioaugmentation process was tested using four hydrocarbonoclastic fungal strains isolated from the same contaminated mining soil individually and a mixed culture of the four isolates. The molecular characterization of the isolated fungi was based on sequence analysis of 18S rRNA, and the fungi were identified as Aspergillus niger MT786339.1, Aspergillus fumigatus MT786338.1, Aspergillus terreus MT786341.1, and Aspergillus flavus MT786340.1. The best TPH removal was achieved by inoculation with the fungal consortium (57 ± 1.97%) at 45 days (slow stage) after initiating the biostimulation process, followed by inoculation with Aspergillus niger (49 ± 1.2%), Aspergillus terreus (44 ± 0.67%), Aspergillus fumigatus (35 ± 0.98%), and Aspergillus flavus (32 ± 0.38%), while the degradation rate achieved with native microorganisms was only 21.6 ± 1.5%; statistical analysis of the results showed significant differences.

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