Periodical biostimulation with nutrient addition and bioaugmentation using mixed fungal cultures to maintain enzymatic oxidation during extended bioremediation of oily soil microcosms

New challenges are associated with crude oil biodegradation by microorganisms during extended bioremediation due to decreasing enzymatic oxidation. In the present study, strategies to maintain enzymatic oxidation during the extended bioremediation of oily soil microcosms were examined using periodic biostimulation and bioaugmentation (PBB). PBB was employed with the addition of 10 ml malt extract liquid medium (the biostimulation treatment) and 2 g pre-grown fungus in wood meal (the bioaugmentation treatment) to soil artificially contaminated with PHCs 15, 30, 60, and 90 d after the first experiment. Two kinds of fungal co-cultures: Pestalotiopsis sp. NG0071Polyporus sp. S133 (1/1) and Pestalotiopsis sp. NG007/Po/yporus sp. S133/Trametes hirsuta D7 (1/1/1), were examined in order to compare the effects of two or three fungal strains on the crude oil degradation. The results obtained showed that PBB stimulated the biodegradation of crude oils and all fungal co-culture systems used in this study exhibited stronger enzymatic activities (C120, MnP, and laccase) after PBB. Furthermore, PBB using three fungal strains (NG007/S133/D7) exhibited the most effective degradation, and it was possible to maintain enzymatic activities after extended bioremediation. This study offers an important strategy to remediate PHC-contaminated environments by PBB using mixed fungal cultures, specifically for extended biodegradation. (C) 2016 Elsevier Ltd. All rights reserved.