Efficiency of surfactant-enhanced bioremediation of aged polycyclic aromatic hydrocarbon-contaminated soil: Link with bioavailability and the dynamics of the bacterial community

CECOTTI, MARTINA; VIERA, MARISA; MORA, VERÓNICA C.; COPPOTELLI, BIBIANA M.; CECOTTI, MARTINA; MORELLI, IRMA S.; VIERA, MARISA; COPPOTELLI, BIBIANA M.; MORELLI, IRMA S.; MORA, VERÓNICA C.

THE SCIENCE OF TOTAL ENVIRONMENT

Elsevier

Año: 2018 vol. 634 p. 224 - 234

0048-9697

Shifts in the bacterial-community dynamics, bioavailability, and biodegradation of polycyclic aromatic hydrocarbons (PAHs) of chronically contaminated soil were analyzed in Triton X-100?treated microcosms at the criticalmicelle concentration (T-CMC) and at two sub-CMC doses. Only the sub-CMC-dose microcosms reachedsorbed-PAH concentrations significantly lower than the control: 166 ± 32 and 135 ± 4 mg kg−1 dry soil versus266 ± 51 mg kg−1; consequently an increase in high- and low-molecular-weight PAHs biodegradation was observed. After 63 days of incubation pyrosequencing data evidenced differences in diversity and composition between the surfactant-modified microcosms and the control, with those with sub-CMC doses containing apredominance of the orders Sphingomonadales, Acidobacteriales, and Gemmatimonadales (groups of knownPAHs-degrading capability). The T-CMC microcosm exhibited a lower richness and diversity index with a markedpredominance of the order Xanthomonadales, mainly represented by the Stenotrophomonas genus, a PAHs- andTriton X-100?degrading bacterium. In the T-CMC microcosm, whereas the initial surface tension was35 mN m−1, after 63 days of incubation an increase up to 40 mN m−1 was registered. The previous observationand the gas-chromatography data indicated that the surfactant may have been degraded at the CMC by a highlyselective bacterial community with a consequent negative impact on PAHs biodegradation. This work obtainedstrong evidence for the involvement of physicochemical and biologic influences determining the different behaviors of the studied microcosms. The results reported here contribute significantly to an optimization of,surfactant-enhanced bioremediation strategies for chronically contaminated soil since the application of dosesbelow the CMC would reduce the overall costs.