Biocatalytic generation of Mn(III)‐chelate as a chemical oxidant of different environmental contaminants

Abstract

The objective of this study was to investigate the enzymatic generation of the Mn(3+) -malonate complex and its application to the process of oxidizing several organic compounds. The experimental set-up consisted of an enzymatic reactor coupled to an ultrafiltration membrane, providing continuous generation of Mn(3+) -malonate from a reaction medium containing versatile peroxidase (an enzyme produced by Bjerkandera adusta strain BOS55), H(2) O(2) , MnSO(4,) and malonate. The effluent of the enzymatic reactor was introduced into a batch-stirred reactor to oxidize three different classes of compounds: an azo dye (Orange II), three natural and synthetic estrogens, and a polycyclic aromatic hydrocarbon (anthracene). The enzymatic reactor provided the Mn(3+) complex under steady-state conditions, and this oxidative species was able to transform the three classes of xenobiotics considerably (90-99%) with negligible loss of activity.

Continuous Removal of Nonylphenol by Versatile Peroxidase in a Two-Stage Membrane Bioreactor

“…The maximum concentration in the enzymatic reactor was 616±42 μM, 1.5-fold higher than the value previously reported [25], probably due to the higher rates of Mn 2+ feeding (1.5 and 1.0 μM h −1 , respectively). According to this value, the maximum efficiency of conversion of Mn 2+ to Mn 3+ was 49 %, which is in agreement with previous findings where the conversion efficiency was around 42 % [22].…”

“…Due to the high removal efficiencies observed in both experiments, these results suggested that at very low concentrations of NP (e.g., 454 nM), the reactor capacity is used only partially and probably the Mn 3+ -complex feeding rate was exceeding that required to achieve the oxidation of NP. Taboada-Puig et al observed that the higher the initial concentration of the Mn 3+ complex, the higher the percentage of the batch oxidation of the synthetic dye Orange II [22]; however, they evaluated molar ratios considerably lower than those studied in the present work (maximum molar ratio of 2.6).…”

“…The addition of the cofactors was carried out by two continuous peristaltic pumps: one for H 2 O 2 at 1.8 ml min −1 (1.5 mM h −1 ) and the other for the solution of sodium malonate and MnSO 4 at 3.6 ml min −1 (15 and 1.5 mM h −1 , respectively) [22]. The enzymatic reactor was operated at a hydraulic retention time (HRT) of 50 min at pH 4.5 and 30°C.…”

“…Later, Sasaki et al developed a similar batch two-stage reactor to perform pulp biobleaching [21]. More recently, our research group developed a two-stage bioreactor for the continuous degradation of the dye Orange II by the Mn 3+ complex [22]. In the present research, we propose to use this system for the removal of a much more recalcitrant micropollutant: NP, present in a real wastewater matrix at environmental concentrations.…”

EPR and LC-MS studies on the mechanism of industrial dye decolorization by versatile peroxidase from Bjerkandera adusta

“…The heterologous expression of VP in Aspergillus nidulans confirmed the ability of VP to oxidize Mn(II), and different aromatic compounds in the absence of manganese (RuizDueñas et al 1999b). The enzymatic generation of Mn(III) by VP for the oxidation ex situ of different pollutants has been proved (Taboada-Puig et al 2011). In addition, this enzyme has a long-range electron transfer (LRET) pathway similar to that shown in lignin peroxidase (LiP) (Johjima et al 1999;Blodig et al 1999;Ruiz-Dueñas et al 2009).…”