Decolourization of Congo Red by Ganoderma lucidum Laccase: Evaluation of Degradation Products and Toxicity

Abstract

Several laccases from different sources have been used in dye decolourization processes. However, only in a reduced number of studies have efforts been done to identify the metabolites produced by the enzymatic treatment as well as to evaluate the toxicity of degradation products. Taking these gaps into account, the objective of this work was to use a laccase from Ganoderma lucidum in the decolourization of the synthetic dye Congo red (C.I. No. 22120, Direct Red 28), largely used in the textile industry. After 6 h of treatment at pH 4.0 and 40°C, the enzyme was able to decolourize 80 % of Congo red. Fourier transform infrared spectroscopy (FTIR), photoacoustic spectroscopy (PAS) and mass spectrometry allow concluding that laccase effectively changed the structure of Congo red, reducing the colour by modifying the chromophore groups and other parts of the molecule. Several degradation products with m/z + ranging from 298 to 745 were identified. It is proposed that the first degradation step could be an asymmetric cleavage of the azo bond present in the Congo red structure forming the intermediate with m/ z + 298. The results also suggest a reduction in the toxicity of Congo red after laccase treatment, as indicated by the lettuce seed germination model. In conclusion, G. lucidum laccase could be used in a novel azo dye bioremediation strategy.

<b>Strategies for decolorization of textile industry effluents by white-rot-fungi with peach palm residue

“…Regarding the manganese peroxidase, its production was negligible under all experimental conditions assayed. Similar results have been reported by Mota et al (2015) who observed that G. lucidum did not produce MnP.…”

Mechanical and thermal properties of low density polyethylene composites filled with dye‐loaded shell powder

“…The FTIR spectra of PSP, DPSP and CR in Figure exhibit the following absorption bands and they are assigned referring to the literatures . In the spectrum of PSP, the bands located at 711.87, 876.31, and 1420.02 cm −1 are ascribed to the in‐plane bending, out‐of‐plane bending, and asymmetric stretch vibrations of groups, respectively .…”

Adsorptive removal of cationic and anionic dyes from aqueous solution by utilizing almond shell as bioadsorbent

“…The selected dyes are common pollutants in the environment, but nevertheless they are less studied compared to other dyes such as Methylene Blue (Chairunnisa et al 2016;Saghanejhad Tehrani and Zare-Dorabei 2016) and Red Congo dyes (Dawood and Sen 2012;Mota et al 2015). The physicochemical properties and the composition of the prepared bioadsorbents were studied with the help of characterization methods.…”