Enhanced laccase-mediated transformation of diclofenac and flufenamic acid in the presence of bisphenol A and testing of an enzymatic membrane reactor
Hahn et al. AMB Expr
Enhanced laccase-mediated transformation of diclofenac and flufenamic acid in the presence of bisphenol A and testing of an enzymatic membrane reactor
Veronika Hahn 0 2
Mareike Meister 0 2
Stephan Hussy 1
Arno Cordes 4
Günther Enderle 1
Akuma Saningong 3
Frieder Schauer 0
0 Institute of Microbiology, Ernst-Moritz-Arndt-University Greifswald , Friedrich-Ludwig-Jahn-Str. 15, 17487 Greifswald , Germany
1 Atec Automatisierungstechnik GmbH , Emmi-Noether-Str. 6, 89231 Neu-Ulm , Germany
2 , 73479 Ellwangen , Germany
3 EurA Consult AG , Max-Eyth-Str
4 ASA Spezialenzyme GmbH , Am Exer 19 C, 38302 Wolfenbüttel , Germany
The inadequate removal of pharmaceuticals and other micropollutants in municipal wastewater treatment plants, as evidenced by their detection of these substances in the aquatic environment has led to the need for sustainable remediation strategies. Laccases possess a number of advantages including a broad substrate spectrum. To identify promoting or inhibitory effects of reaction partners in the remediation processes we tested not only single compounds-as has been described in most studies-but also mixtures of pollutants. The reaction of diclofenac (DCF) and flufenamic acid (FA), mediated by Trametes versicolor laccase resulted in the formation of products, which were more hydrophilic than the respective reactant (reactant concentration of 0.1 mM; laccase activity 0.5 U/ml). Analyses (HPLC, LC/MS) showed that the product 1a and 1b for DCF and FA, respectively, to be a para-benzoquinone imine derivative. The formation of 1a was enhanced by the addition of bisphenol A (BPA). After 6 days 97% more product was formed in the mixture of DCF and BPA compared with DCF tested alone. Product 1a was also detected in experiments with micropollutant-supplemented secondary effluent. Within 24 h 67% and 100% of DCF and BPA were transformed, respectively (25 U/ml). Experiments with a membrane reactor (volume 10 l; phosphate buffer, pH 7) were in good agreement with the results of the laboratory scale experiments (50 ml). EC50-values were also determined. The data support the use of laccases for the removal or detoxification of recalcitrant pollutants. Thus, the enzyme laccase may be a component of an additional environmentally friendly process for the treatment stage of wastewater remediation.
Quinone; Bioremediation; Detoxification; Pharmaceuticals; Biodegradation; Vibrio fischeri
Introduction
The daily use of anti-inflammatory drugs such as
diclofenac (DCF) or flufenamic acid (FA) in creams or
tablets, as well as of plastic materials which release
bisphenol A (BPA), contributes to pollution with these
environmentally dangerous compounds. BPA is used
in plastic industries; consequently the release from
different sources is conceivable such as packages for food
and drink, varnishes, paintings and glues
(Barnabe et al.
2009)
. The main entries for pharmaceuticals such as DCF
or FA in ground and surface water are sludge or
effluents of wastewater treatment plants (WWTP) where the
pollutants are insufficiently degraded. Another source is
dung and manure of farm animals which were treated
with these substances
(Ternes 1998; Deblonde et al. 2011;
Samaras et al. 2013; Carmona et al. 2014)
.
Only 17–69% of DCF is removed in sewage treatment
plants
(Ternes 1998; Zwiener et al. 2000; Heberer 2002a;
Heberer and Feldmann 2005; Deblonde et al. 2011;
Samaras et al. 2013)
. FA is also insufficiently removed in
WWTP. Moreover,
Gracia-Lor et al. (2012
) and Carmona
et al. (2014) described for DCF and FA higher
concentrations in the effluent than in the corresponding influent of
spanish WWTP. The authors proposed a release as result
of a cleavage of transformation products, deconjugation
of metabolites and desorption from organic material.
DCF, FA and BPA were found repeatedly in
surface water.
Ternes (1998)
reported for DCF a median
of 0.15 µg/l and a maximum of 1.20 µg/l for German
river and stream water. In Berlin, up to 0.5–1 µg/l and
0.38 µg/l were found in the Teltowkanal and in ground
water, respectively
(Heberer 2002b)
. FA was detected in
river and tap water with average concentrations of 21
and 16 ng/l, respectively (Carmona et al. 2014). BPA was
also found in surface and ground water
(Loos et al. 2009,
2010)
. In small streams of the German region called
Hessisches Ried BPA concentrations of up to 1.92 µg/l were
detected (Quednow and Püttmann 2008).
DCF, FA as well as BPA may cause toxic effects. In
rainbow trout DCF accumulates in the bile to a factor
of approximately 580, and additionally the tested
environmentally relevant concentrations caused necrosis
in the kidney
(Mehinto et al. 2010)
. The endocrine
disrupting compound BPA leads to the induction of
feminization in aquatic organisms, such as frogs
(Levy et al.
2004; Bhandari et al. 2015)
. Because of the potential
risk for human health, DCF was included in a watch list
of emerging pollutants by the EU
(Commi (...truncated)