Repeated batch for dye degradation in an airlift bioreactor by laccase entrapped in copper alginate

Abstract

Abstract16 A repeated batch of synthetic dye decolorization was efficiently demonstrated in a 5 L airlift 17 bioreactor. A laccase from Ganoderma sp. KU-Alk4, degrading commercial aromatic dyes was 18 selected. The crude enzyme extract expressed laccase activity, and was immobilized under optimal 19 conditions in copper-alginate beads, 3 IU/bead. The immobilized enzyme showed high efficiency 20 in degrading various synthetic dyes under non-buffered conditions, in particular the indigoid dye 21 Indigo Carmine. The immobilized laccase also showed marked increase in stability toward 22 temperature and pH when compared with free enzyme preparation. Immobilization enhanced its 23 temperature stability to maintain initial activity up to 55 °C, ten degrees higher than the free 24 enzyme. The immobilized laccase was stable in the alkaline region up to pH 10.0. The dye 25 decolorization system in 5 L airlift bioreactor was demonstrated with 25 mg/L Indigo Carmine 26 dissolved in tap water and a total immobilized laccase activity of 6x10 4 IU. Airflow rate was the 27 most important factor affecting the number of batch runs and the time for 100% dye degradation. 28 An optimal airflow rate was of 4 L/min. Fourteen batch runs of complete dye degradation were 29 successfully completed with only a single enzyme supplementation, and this could be a feasible 30 system for operation in industry. Total dye degraded by this repeated process at 4 L/min airflow 31 rate was 1.8 g. Isatin sulfonic acid was a metabolic product of Indigo Carmine degradation 32 catalyzed by the immobilized laccase. This development of an effective repeatable bioprocess 33 using enzymes for the treatment of dye-contaminated effluent has potential for implementation on 34 an industrial scale.

Two Manganese Peroxidases and a Laccase ofTrametes polyzonaKU-RNW027 with Novel Properties for Dye and Pharmaceutical Product Degradation in Redox Mediator-Free System

“…Laccase of Ganoderma sp. KU-Alk4 also showed high ability to decolorize Indigo carmine and 12 U/mL of the laccase completely degraded 25 mg/L of Indigoid dye in 24 h. Complete indigo carmine degradation was successfully demonstrated in a 5 L-airlift reactor for 14 cycles [6]. Addition of a redox mediator as violuric acid and acetosyringone was suggested to improve activity of ligninolytic enzymes in dye decolorization [38].…”

“…MnP and laccase assays followed previously described methods [6,33]. MnP and laccase activities were determined by monitoring oxidation of 2,6-DMP at 469 nm.…”

“…Ligninolytic enzymes including manganese peroxidase (MnP), laccase, and lignin peroxidase (LiP), in particular from white rot fungi, have oxidizing abilities which make them attractive candidates for an eco-friendly approach to bioremediation of persistent phenolic and non-phenolic contaminants. [4][5][6][7][8]. Manganese peroxidase (EC 1.11.1.13, Mn(II): hydrogen-peroxide oxidoreductase) is a member of class II fungal secretion heme peroxidase in subfamily A.…”

Detoxification and Bioremediation of Sulfa Drugs and Synthetic Dyes by Streptomyces mutabilis A17 Laccase Produced in Solid State Fermentation

“…Optimal pH and pH stability of purified enzyme was studied according to a protocol described by El-Batal et al 30 . The pure enzyme was separately incubated for 30 min with citrate phosphate buffer for pH (5)(6)(7)(8) and Glycine-NaOH for pH (9)(10)(11). The pH stability of enzyme was studied when its incubated at different pH values (5)(6)(7)(8)(9)(10)(11) for 2h at 35°C.…”

“…Laccases have numerous potential in bioremediation, biofuel production, removal of water and soil wastes, and modification of biopolymers 4 and also synthetic dyes decolorization 2 . The presence of synthetic dyes in dye manufacturing, sewages of textile and leather tanning industries causes an environmental pollutions due to their toxic effect on plants, animals and also on human health 5 . The toxicity degree of degradation products depends on their structure which determines the structure of degraded dyes and enzymes used for their degradation 6 .…”