Production, characterization and Congo red dye decolourizing efficiency of a laccase from Pleurotus ostreatus MTCC 142 cultivated on co-substrates of paddy straw and corn husk

Abstract

A laccase produced by Pleurotus ostreatus MTCC 142 under solid-state fermentation using co-substrates of paddy straw and corn husk (1.5:1.5, g w/w) showed an activity of 2.54 U gds−1. Laccase activity was determined spectrophotometrically using 0.5 mM 2,2′- azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) (ABTS). Supplementation with fructose and potassium nitrate resulted in maximum enzyme production at initial pH 5.8 ± 0.2 and initial moisture content of 70%. A carbon: nitrogen ratio of 0.5:0.1 yielded highest laccase activity in the presence of surfactant Tween 20 (0.05%, w/v). Incorporation of vanillin (5 mM) and copper sulphate (10 mM) facilitated enhanced synthesis of laccase. A 4.8-fold increase in enzyme activity was recorded after optimization of nutritional parameters. The apparent molecular mass of this enzyme was revealed as 43 kDa by sodium dodecyl sulphate–polyacrylamide gel electrophoresis. The laccase showed optimal activity at pH 3 and 35 °C with 82.8% residual activity after 1 h of incubation. The Km and Vmax values on ABTS were found to be 0.52 mM and 9.33 U gds−1, respectively. The enzyme activity was enhanced by Cu2+ and remained unaffected with Ba2+, Mn2+, Pb2+, Mg2+, Ca2+ and Fe3+. However, pre-incubation of the enzyme with reagents like sodium azide, sodium lauryl sulphate and 2-mercaptoethanol demonstrated an inhibition of its activity. Addition of crude laccase to Congo red dye solution resulted in 36.84% decolourization after 20 h of incubation at 35 ± 2 °C. This study discusses the production and characterization of a laccase from P. ostreatus strain with potential for azo dye decolourization.

Azo Dye Mineralization by Phanerochaete Chysosporium in a Sequencing Bath Reactor

“…The role of the use of co-substrate in the bioremediation of textile dyes is relevant due to the complexity of the molecular structure of these compounds. The co-substrate has influence on the enzymatic production, as reported by Das et al (2016) 18 , which obtained higher enzymatic activity of laccase in media containing fructose, sucrose and glucose, with values between 0.5 and 0.6 U.gds -1 . The co-substrate addition occurs until an optimal range of concentration, above which no efficiency is observed in the process of treatment of textile effluents.…”

“…Many dyes are substrates for the laccase which acts as a cathode that greatly increases the range of dyes that can be effectively removed from the medium and the rate of removal. Moreover, in the presence of living cells and due to their complete metabolic network, the assimilation of intermediate compounds can occur 18 . These intermediate compounds may be from aromatic amines, carboxylic acids, alcohols and esters derived from the degradation of the dye molecule 19 .…”

The optimization of propagation medium for the increase of laccase production by the white-rot fungus Pleurotus ostreatus

“…Inorganic nitrogen sources were not appropriate for the effective biomass growth. Organic sources can provide proteins and amino acids resulting to more abundant growth of the fungus (Das et al 2016). El-Batal et al (2015) similarly found that organic nitrogen sources were better alternative for the biomass growth than inorganic nitrogen sources.…”

“…Cellulases are probably constitutively produced during the cultivation. P. ostreatus is a white-rot fungus which can produce lignolytic enzymes, namely manganese peroxidases (MnP) and laccases (Das et al 2016) which can oxidize ABTS used as the substrate. Therefore, the presence of these enzymes in the media was determined by native-PAGE.…”

Avaliação do potencial de descoloração e de detoxificação de corantes têxteis por lacase de Pleurotus sajor-caju

“…Estes, quando lançados no ambiente aquático, reduzem a disponibilidade de luz e a realização da fotossíntese e ocasionam outros problemas ambientais. Além disso, a maioria dos corantes têxteis são 5,7,8,13 Lacases pertencem à família das multi-cobre azuis oxidases (OMC), com capacidade de oxidar, polimerizar ou transformar compostos fenólicos, não fenólicos e antropogênicos em derivados menos tóxicos. Dessa forma, são consideradas de grande potencial para utilização em diversos processos de remediação em substituição aos processos químicos, promovendo ações ecologicamente sustentáveis.…”