Potentiality of Native Ascomycete Strains in Bioremediation of Highly Polychlorinated Biphenyl Contaminated Soils.

Joaquim Germain,Muriel Raveton,Marie-Noëlle Binet,Bello Mouhamadou

doi:10.3390/microorganisms9030612

Abstract

Polychlorinated biphenyls (PCBs) are organic pollutants that are harmful to environment and toxic to humans. Numerous studies, based on basidiomycete strains, have reported unsatisfactory results in the mycoremediation of PCB-contaminated soils mainly due to the non-telluric origin of these strains. The abilities of a five-Ascomycete-strain consortium in the mycoremediation of PCB-polluted soils and its performance to restore their sound functioning were investigated using mesocosm experiments associated with chromatography gas analysis and enzymatic activity assays. With the soil H containing 850 ppm PCB from which the strains had been isolated, a significant PCB depletion of 29% after three months of treatment was obtained. This led to an important decrease of PCBs from 850 to 604 ppm. With the soil L containing 36 ppm PCB, biodegradation did not occur. In both soils, the fungal biomass quantified by the ergosterol assay, did not increase at the end of the treatment. Biodegradation evidenced in the soil H resulted in a significantly improved stoichiometry of N and P acquiring enzymatic activities. This unprecedented study demonstrates that the native Ascomycetes display remarkable properties for remediation and restoration of functioning of the soil they originated from paving the way for greater consideration of these strains in mycoremediation.

Highlights

While most studies have explored the ability of ligninolytic Basidiomycete strains in the mycoremediation of Polychlorinated biphenyls (PCBs)-polluted soils [2,4,14,15,31] and have shown in most cases underwhelming results [16], very few studies have investigated the potentiality of Ascomycete strains isolated from PCB-polluted soils to degrade these recalcitrant pollutants
The consortium of five native Ascomycete strains isolated from the soil H demonstrated its capacity to partially remediating it by degrading 27% of the seven indicator PCBs
This led to an important decrease of PCBs from 850 ppm to 604 ppm

Summary

Introduction

Polychlorinated biphenyls are organochlorine compounds consisting of a biphenyl core substituted by one to 10 chlorine atoms with 209 possible congeners differing in the number of chlorine atoms and their position on the biphenyl core [1]. These synthetic compounds have been largely used in industrial products due to their thermal and chemical stability, dielectric properties and low flammability [1,2]. They have become a global problem due to their high adsorption capacity in soil and sediment, to their low water solubility, to their capacity to bioaccumulate in fatty tissues, and to their toxicity to animals and humans [9,10,11,12]

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