Use of stable isotope probing to assess the fate of emerging contaminants degraded by white-rot fungus

The widespread of emerging contaminants in the environment and their potential impact on humans is a matter of concern. White-rot fungi are cosmopolitan organisms able to remove a wide range of pharmaceuticals and personal care products (PPCP) through cometabolism (i.e. laccases and peroxidases) or detoxification mechanisms (i.e. cytochrome P450 system). However, the use of PPCP as carbon source for these organisms is largely unexplored. Here, we used carbon stable isotope tracer experiments to assess the fate of anti-inflammatory diclofenac (DCF) and UV filter benzophenone-3 (BP3) during degradation by Trametes versicolor. The comparison between carbon isotopic composition of emitted carbon dioxide from C-13-labelled DCF ([acetophenyl ring-C-13(6)]-DCF) and C-13-BP3 ([phenyl-C-13(6)]-BP3) versus their C-12-homologue compounds showed mineralization of about 45% and 10% of the C-13 contained in their respective molecules after 9 days of incubation. The carbon isotopic composition of the bulk biomass and the application of amino acid-stable isotope probing (SIP) allowed distinguishing between incorporation of C-13 from BP3 into amino acids, which implies the use of this emerging contaminant as carbon source, and major intracellular accumulation of C-13 from DCF without implying the transformation of its labelled phenyl ring into anabolic products. A mass balance of C-13 in different compartments over time provided a comprehensive picture of the fate of DCF and BP3 across their different transformation processes. This is the first report assessing biodegradation of PPCP by SIP techniques and the use of emerging contaminants as carbon source for amino acid biosynthesis. (c) 2013 Elsevier Ltd. All rights reserved.