Browsing by Author "Edoamodu, C."

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    Decolourization of synthetic dyes by laccase produced from Bacillus sp. NU2
    (Taylor and Francis, 2022-03-09) Edoamodu, C.; Nwodo, U.
    Advanced industrialization has caused an increase in the continuous discharge of hazardous effluents in the environment. This study evaluated the potential of the laccase synthesized by Bacillus sp. NU2 to degrade five synthetic dyes. Sawdust, wheat bran and peels of banana and tangerine were utilized as carbon sources for bacterial growth and laccase production. The produced crude enzyme was purified to homogeneity to determine its molecular weight. The kinetic activity of the purified laccase was determined using 2,2′-azinobis-(3-ethylbenzothiaz oline-6-sulfonic acid) (ABTS). The toxicity of the laccase-treated dye solution was assessed on Bacillus sp. NU2 growth. The result showed optimum laccase yield from the tangerine peel medium. The purified laccase gave a specific activity of 349.94U mg−1 and a molecular weight of 55kDa, respectively. The purified laccase displayed a strong affinity for ABTS substrate with an enzyme activity of 31.21U mg−1. It was optimum at 60°C and pH 8, with catalytic efficiency (Kcat/Km) of 23.93mmol L−1. The decolourization effects on Congo Red, Methyl Orange, Remazol Brilliant Blue R, Reactive Blue 4 and Malachite Green were 87%, 70%, 65%, 63% and 51%, respectively. The toxicity assay of laccase degraded dyes on Bacillus sp. NU2 showed a growth reduction of 36.75% (Malachite Green), 12.57% (Congo Red), 17.19% (Methyl Orange), 38.41% (Remazol Brilliant Blue R) and 28.14% (Reactive Blue 4). The laccase produced by Bacillus sp. NU2 holds a high catalytic potential for the detoxification of dye effluents in an environmental system.
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    Thermo-active and alkaliphilic amalgamated laccase immobilized on sodium alginate for synthetic dye decolourization
    (2022-05-12) Edoamodu, C.; Nwodo, U.
    Purified crude laccase of Enterobacter sp. Kamsi and Bacillus sp. NU2 in the hybrid and combined form was immobilized on sodium alginate beads and applied to decolourize various textile dyes through several decolourization reaction cycles. The enzyme/alginate (E/A) loading efficiency and immobilization yield were evaluated. The SEM-EDX analysis, pH, and temperature effects of both forms of immobilized laccases were examined. The maximum condition for Kamsi and NU2 laccases into Na-alginate beads is 2.5% (w/v), which resulted to >83 and 61.71% immobilization and loading efficiency, respectively. The SEM-EDX analysis showed a rough-spherical surface attributable to significant entrapment of the laccase at the centre of the beads. The hybrid laccase in the free and immobilized form showed >52% and 80% decolourization effects, while the amalgamated laccase showed >63 and 83% decolourizing effect on Malachite Green (MG), Remazol Brilliant Blue R (RBBR), Reactive Blue 4 (RB4), Congo Red (CR), and Methyl Orange (MO), respectively. The immobilized laccase retained >50 and 81% activity of the hybrid and amalgamated laccases, respectively, after six successive treatment cycles. The results showed that the immobilization technique of the Kamsi and NU2 laccase holds the potential for textile dye effluents degradation, but the amalgamation of an enzyme from different species could improve decolourization potentials for various dyestuff treatments.