Page 166 - Materials Chemistry, Second Edition

Fungal Treatment of Pharmaceuticals in Effluents 147

trogii, Cerrena unicolor 137, and Panustigrinus. The isozymes secreted from dif-
ferent species have specific isoelectric points (pI), molecular weights (MW), and
pH and temperature optima (Cadimaliev et al., 2005; Lorenzo et al., 2006; Mäkelä
et al., 2006; Michniewicz et al., 2006; Zouari-Mechichi et al., 2006). Laccases are
able to oxidize phenolic compounds, but in the presence of certain mediator com-
pounds, they can also oxidize non-phenolic aromatic compounds (Upadhyay et al.,
2016; Harms et al., 2011). Studies have indicated the potential of fungal laccases
to decolorize and detoxify both dye-containing effluents and EDCs (Harms et al.,
2011). Studies with the laccases of Trametes versicolor and other fungi have shown
promise in the bioremediation of several pharmaceutical pollutants (Junghanns et
al., 2005; Lloret et al., 2010, 2012; Tran et al., 2010; Strong and Claus, 2011; Margot
et al., 2013 Rodríguez-Rodríguez et al., 2012b; Ba et al., 2014a,b; Macellaro et al.,
2014; Rodríguez-Delgado et al., 2016; Tahmasbi et al., 2016; Becker et al., 2017).
Other extracellular fungal enzymes also exist and may be important in the
metabolism of some pharmaceutical pollutants (Harms et al., 2011; Kües, 2015).
A living fungus will use its extracellular enzymes in coordination with its intracel-
lular enzymes to metabolize many organic substrates. For that reason, there may be
advantages to using live fungi instead of isolated enzymes from the fungi to remedi-
ate pharmaceutical wastes. Using fungi for bioremediation is still an infant field of
endeavor, and many things remain to be learned. There may be situations in which
immobilized fungal enzymes are more useful for remediating organic wastes than
are living fungi (Kües, 2015).
Fungi, including WRF, need intracellular enzymes to function at least as well as
their extracellular enzymes. The extracellular and intracellular enzymes coordinate
with one another to accomplish different tasks. Among the intracellular enzymes,
the O -requiring P450 monooxygenases (also called mixed function cytochrome
2
P450 oxidases) are especially interesting. Found in ascomycetes, basidiomycetes,
and many other fungal groups, they carry out both biosynthetic and catabolic tasks.
They have low substrate specificity and catalyze epoxidations, hydroxylations, and
other modifications of many types of organic compounds. They may be at least as
important as extracellular enzymes in some bioremediation situations. Cytochrome
P450 oxidases have been implicated in enabling fungi to metabolize a variety of
pharmaceuticals, including anti-inflammatory drugs, anti-epileptics, anti-analgesics,
and lipid regulators (Kües, 2015; Harms et al., 2011). Several studies have estab-
lished the involvement of cytochrome P450 oxidases in the metabolism of various
pollutants, including pharmaceutical waste (Marco-Urrea et al., 2009; Subramanian
and Yadav, 2009; Črešnar and Petrič, 2011; Golan-Rozen et al., 2011; Wang et al.,
2013; Vasiliadou et al., 2016; Durairaj et al., 2016).

8.4 MODES OF ACTION—TECHNIQUES EMPLOYED TO DATE
The PhACs in the influent of WWTPs present a broad variety of compounds with
different concentrations ranging from several milligrams per liter to ultra-trace con-
centrations of nanograms per liter, as discussed in the previous section. The method
employed for analyzing the compounds depends on several factors, including the
type and nature of the analyte, the concentration, the type of the employed organism,