Characterization of yellow bacterial laccase SmLac/role of redox mediators in azo dye decolorization

Abstract

BACKGROUND: The bacterial Stenotrophomonas maltophilia AAP56 laccase (SmLac) has been purified from cell extracts and its spectral and kinetic properties studied. It shows a high decolorization rate (99%) of the diazoic dye Reactive Black 5 (RB5) in the presence of redox mediators such as ABTS (2,2 -azino-bis(3-ethylbenzthiazoline-6-sulfonic acid), ASGN (Acetosyringone), SGA (Syringaldehyde) and HOBT (1-Hydroxy-Benzotriazole). The optimal pH has been determined as neutral or basic compatible with textile wastewater pH for further treatment application.

Over-activity and stability of laccase using ionic liquids: screening and application in dye decolorization

“…To study the influence of the cationic and anionic composition of ILs on the activity of laccase, a systematic study was carried out using 56 different ILs (see Table 1), 26 of which were water-immiscible and 30 water-miscible (see Table 1). The 4 ]. The 4 ].…”

“…4-85 B shows that the increasing of [Chol][H 2 PO4 ] concentration gradient have a decreasing effect on β-sheet structure peaks absorption at 1645 cm -1 . Moreoever, two large peaks 80 assigned to Amide II and Amide I, respectively, were recorded at 1583 cm −1 and 1648 cm −1 .…”

Pilot scale production of extracellular thermo‐alkali stable laccase from Pseudomonas sp. S2 using agro waste and its application in organophosphorous pesticides degradation

“…This result is in agreement with a previous report which demonstrated that copper center T2 band appeared in the invisible domain (and any characteristic band in the visible domain has been observed). The addition of copper causes the translation of the peak to 245 nm; this is normal for metallo‐protein when fixing its molecular metal . Therefore, these results suggest that the copper added to the enzyme is probably fixed by the copper center T2 with no observed weak band at 610 nm (characteristic of T1‐Cu II center) nor at 330 nm (characteristic of T3 copper center).…”

New efficient laccase immobilization strategy using ionic liquids for biocatalysis and microbial fuel cells applications

“…). In fact, ABTS was used as substrate in the first part of the work since it has been described as a high affinity laccase substrate in several works and, furthermore, ABTS is one of the best mediators of laccase catalysis which contributed in free laccase to increasing the electron driving force between enzyme and high redox potential substrates, and to improving the electro‐analytical performance of immobilized fungal laccase on multi‐walled carbon nanotubes electrodes. In biofuel cells, ABTS is commonly used as substrate for several immobilized laccases for electron generation .…”

“…On the one hand, ABTS has been widely used as laccase substrate with high affinity (for instance, the apparent km was determined at 35 M by Galai et al 15 ) and, on the other hand, ABTS has been widely described as the best laccase mediator in various applications, for instance for bio-decolorization of Reactive Black 5. 21 Therefore, using ABTS as an alternative for improving the electronic efficiency of laccase in the present work was seen as a good choice since ABTS simultaneously played the role of substrate and redox mediator. This fact contributed to improving the output of the laccase in electron shuttling and consequently in the reduction of oxygen to water.…”