Bioremediation of soil contaminated with pentachlorophenol by Anthracophyllum discolor and its effect on soil microbial community

Abstract

Bioaugmentation is a promising technology to clean up sites contaminated with recalcitrant chemicals. White-rot fungi have proven to be effective in the degradation of pentachlorophenol. Here, we report the bioremediation of soil contaminated with pentachlorophenol (PCP) by Anthracophyllum discolor and its impact on the soil microbial community. In this study three types of microcosms were established: fresh soil (C(0)), fresh soil plus wheat straw (WS(0)) and, fresh soil plus wheat straw inoculated with A. discolor (WSAD(0)). Additionally, similar treatments and a control of sterile soil spiked with PCP (C(250), WS(250) and WSAD(250)) were used to evaluate the remediation and adsorption of PCP. The PCP removal, total microbial activity, and enzymatic activities were evaluated. This study also investigated the structure of soil microbial community by denaturing gradient gel electrophoresis (DGGE), identifying some of the dominant bacterial and fungal species. The results showed that PCP was effectively degraded in soils by A. discolor and by indigenous soil microorganisms. The addition of wheat straw increased the PCP degradation and enzymatic activities. Only laccase activity was negatively affected by PCP contamination. The PCP degradation was associated with changes in microbial communities, mainly stimulation of members of bacterial phylum Proteobacteria (Xanthomonadaceae, Burkholderiaceae and Enterobacteriaceae), and fungal phylum Ascomycota and Basidiomycota. This study shows the ability of A. discolor to degrade PCP from contaminated soil, and demonstrates that agricultural residues, such as wheat straw, can be used as growth substrate by microorganisms in PCP-contaminated soil, demonstrating a great potential of autochthonous microorganisms for soil remediation.