Degradation of azo dyes by laccase: biological method to reduce pollution load in dye wastewater

Abstract

Laccases are the oldest with low substrate specificity enzymes used for degradation of various compounds, especially, dyes. In the present investigation, the cell-free extract of laccase enzyme is applied to degrade azo dyes used in leather processing. The enzyme degrades the azo dyes rapidly at optimum growth conditions of pH 7.0, temperature 37°C and incubation duration of 72 h. Better production of the enzyme was achieved with dextrose, yeast extract, acetone, copper sulphate and orange peel. The molecular weight of laccase was found to be 63 kDa. The percentage of degradation is found to be 96.4 % for CI Acid black 210 and 92.2 % for the CI Acid black 234. Ultraviolet-visible spectral analysis indicates the presence of peaks in the visible region confirming the complete degradation of the dye sample. Fourier transforminfrared spectroscopy analysis shows the transformation of N=N into either N 2 or NH 3 and then into biomass. The mass spectra analysis shows conversion of azo dye to final product through various intermediates with their respective molecular weights. Chemical oxygen demand (COD) and biochemical oxygen demand (BOD) analysis reveal the reduction of pollution load more than 92 % in the experimental process while maintaining BOD/COD ratio to about 30 %.

Bioremediation potential of filamentous fungi in methylene blue: Solid and liquid culture media

“…synthesize specific enzymes on the culture medium (Barrasa et al, 2014;Kanagaraj;Senthilvelan;Panda, 2015). For the P. ostreatus EF60 isolate, the increase in the methylene blue concentration reduced the mycelial diameter at 50 mg L -1 by 38.5%, and the mycelial growth was adjusted to a quadratic regression model.…”

“…Kanagaraj, Senthilvelan and Panda (2015) reported that dyes, when degraded by bioremediation fungi, release ammonia, which is rapidly immobilized by microbial biomass and ensures mycelial growth, discoloration and dye degradation (Kundjadia et al, 2016).…”

“…This metabolic flexibility occurs due to the production of enzymes, such as laccases, that degrade toxic compounds into ammonia to form biomass (Kanagaraj;Senthilvelan;Panda, 2015). However, the bioremediation potential of fungi depends on the species of fungus and the type of substrate (Singh et al, 2011).…”

“…The presence of the enzyme laccase is important in bioremediation studies, and this enzyme does not have substrate specificity, which gives it the potential to be used in the degradation of different compounds (Kanagaraj;Senthilvelan;Panda, 2015). This enzyme can be synthesized by filamentous fungi, such as Pleurotus (Kundjadia et al, 2016;Skariyachanet al, 2016), Fusarium (Wu;Nian, 2013), Alternaria, Aspergillus, Cladosporium, Penicillium, and Rhizopus (Monssef;Hassan;Ramadan, 2016), and by bacteria (Sondiet al, 2014, Ausec et al, 2015Chowdhary, 2015).…”

Impact of Corona Treated Activated Carbon in Anionic and Cationic Dye Adsorption

“…Dye pollution reduction has been exhaustively studied for several years, yet, currently new technologies have been developed to perform and improve dye degradation, making the environment cleaner and reducing pollution. The main and new methods to reduce dye pollution involve activated carbon (GHAEDI et al, 2012), surface modified activated carbons (MOHAMMED et al, 2015), nanoadsorbents (KYZAS; MATIS, 2015), agricultural adsorbent waste (PELÁEZ-CID et al, 2013), other adsorbents (YAVUZ; SAKA, 2013), ozonation (CASTRO et al, 2016), irradiation (HERNÁNDEZ-URESTI et al, 2011), photocatalics (MAHMOODI, 2013, plasma discharge (JIANG et al, 2014), biological methods (KANAGARAJ et al, 2014) and others.…”