Enzymatic decolorization of melanin by lignin peroxidase from Phanerochaete chrysosporium

Skin darkening results as a consequence of the accumulation of skin pigment melanin. To combat this, the amplitude of skin lightening agents are commercially available, most of which inhibit melanin synthesis. Decolorization of melanin is an alternative method of skin lightening. In this study, we show that lignin peroxidase (LiP), an extracellular enzyme purified from Phanerochaete chrysosporium NK-1 isolated from a forest soil can effectively degrade and decolorize melanin in vitro. Decolorization conditions including pH, temperature, incubation time, enzyme concentration, and mediator addition were investigated to optimize the reaction conditions. The results indicate that pH 3, 40 °C, 15 IU/ml, and 10 h incubation were the optimal conditions for the decolorization of the melanin. The use of the mediator, veratryl alcohol was also found effective to enhance the efficacy of the melanin decolonization, with up to 92% decolorization. The scanning electron microscopy results showed void spaces on the treated melanin granules as compared to the untreated sample, indicating the degradation of melanin. Changes in the fingerprint region of the melanin were observed. Between wavenumbers 1500–500 cm−1, for example, the presence of new peaks in the treated melanin at 1513, 1464, and 1139 cm−1 CH2, CH3 bend and C–O–C stretch represented structural changes. A new peak at 2144 cm−1 (alkynyl C≡C stretch) was also detected in the decolorized melanin. The cytotoxicity study has shown that the treated melanin and LiP have low cytotoxic effects; however, the mediator of veratryl alcohol could result in high mortality which suggests that its use should be meticulously tested in formulating health and skincare products. The findings of the study suggest that LiP produced by Phanerochaete chrysosporium has the potential to be used in the medical and cosmetic industries, particularly for the development of biobased cosmetic whitening agents.

Laccase Immobilized onto Zirconia–Silica Hybrid Doped with Cu2+ as an Effective Biocatalytic System for Decolorization of Dyes

Nowadays, novel and advanced methods are being sought to efficiently remove dyes from wastewaters. These compounds, which mainly originate from the textile industry, may adversely affect the aquatic environment as well as living organisms. Thus, in presented study, the synthesized ZrO2–SiO2 and Cu2+-doped ZrO2–SiO2 oxide materials were used for the first time as supports for laccase immobilization, which was carried out for 1 h, at pH 5 and 25 °C. The materials were thoroughly characterized before and after laccase immobilization with respect to electrokinetic stability, parameters of the porous structure, morphology and type of surface functional groups. Additionally, the immobilization yields were defined, which reached 86% and 94% for ZrO2–SiO2–laccase and ZrO2–SiO2/Cu2+–laccase, respectively. Furthermore, the obtained biocatalytic systems were used for enzymatic decolorization of the Remazol Brilliant Blue R (RBBR) dye from model aqueous solutions, under various reaction conditions (time, temperature, pH). The best conditions of the decolorization process (24 h, 30 °C and pH = 4) allowed to achieve the highest decolorization efficiencies of 98% and 90% for ZrO2–SiO2–laccase and ZrO2–SiO2/Cu2+–laccase, respectively. Finally, it was established that the mortality of Artemia salina in solutions after enzymatic decolorization was lower by approx. 20% and 30% for ZrO2–SiO2–laccase and ZrO2–SiO2/Cu2+–laccase, respectively, as compared to the solution before enzymatic treatment, which indicated lower toxicity of the solution. Thus, it should be clearly stated that doping of the oxide support with copper ions positively affects enzyme stability, activity and, in consequence, the removal efficiency of the RBBR dye.

Enzymatic Decolorization of Remazol Brilliant Blue Royal (RB 19) textile dye by White Rot Fungi

Synthetic dyes are widely used by different industries with over 7 ×105 metric tons produce globally each year. Dyes pose adverse effects including chemical oxygen demand, visual pollution, cytotoxicity, genotoxicity, mutagenicity and carcinogenicity on various types of living organisms. The versatile white rot fungi (basidiomycetes fungi) have developed specialized ligninolytic enzymes for reductive cleavage of dyes and xenobiotics. The present study optimized the decolorization of Remazol brilliant blue royal (RBBR) dye by enzymatic extracts of Coriolus versicolor and Pleurotusostreatus. Experiments were carried out by varying one parameter i.e. pH (2.5-6.5), temperature (30oC-60oC), enzyme activity (3.3U-20U), dye concentration (10mg/L-125mg/L) and time (0-480mins), while others constant to study its effects on decolorization of RBBR. From the results obtained, the optimum conditions for decolorization of RBBR by extracts of C. versicolor and P. ostreatus were pH 4.0, temperature of 300C, enzyme activity 20U, dye concentrations of 100mg/L and 50mg/L for C. versicolor and P. ostreatus respectively at the end of 480 minutes. At the optimized conditions, decolorizations for C. versicolor and P. ostreatus were 80.42% and 70.42% respectively. Highest laccase activity (19.50U) was recorded in C. versicolor compare to P. ostreatus (1.41U).