Abstract
Dye-decolorizing peroxidase (DyP) from the white rot basidiomycete Pleurotus ostreatus is a heme peroxidase able to oxidize diverse substrates, including recalcitrant phenols and dyes. This study analyzed the effect of chemical dyes on P. ostreatus growth, DyP activity and the expression of four Pleos-dyp genes during the time-course of Pleurotus ostreatus cultures containing either Acetyl Yellow G (AYG), Remazol Brilliant Blue R (RBBR) or Acid Blue 129 (AB129) dyes. Additionally, Pleos DyP1 was heterologously expressed in the filamentous fungus Trichoderma atroviride in order to explore the potential of a secreted recombinant enzyme for decolorizing different dyes in cultures and plate assays. The addition of dyes had an induction effect on the enzymatic activity, with the fermentations undertaken using RBBR and AYG dyes presenting the highest total DyP activity. DyP gene expression profiles displayed up/down regulation during the culture of three Pleos-dyp genes (Pleos-dyp1, Pleos-dyp2 and Pleos-dyp4), while Pleos-dyp3 transcript was not detected under any of the culture conditions studied. A 14-fold relative induction level (log2) increase for Pleos-dyp2 and Pleos-dyp4 in AB129 and AYG, respectively, was also found. The presence of AB129 resulted in the highest Pleos-dyp1 gene induction and repression level, corresponding to 11.83 and -14.6-fold relative expression and repression levels, respectively. The lowest expression level of all genes was observed in RBBR, a response which is associated with the growth phase. The filamentous fungus Trichoderma atroviride was successfully transformed for the heterologous expression of Pleos-dyp1. The modified strains (TaDyP) were able to decolorize mono-azo, di-azo, anthraquinone and anthracenedione dyes with extracellular DyP1 activity found in the culture supernatant. After 96 h of culture, the recombinant TaDyP strains were able to degrade (decolorize) 77 and 34% of 0.05mM AB129 and 0.25mM AYG, respectively.
Highlights
Dye-decolorizing peroxidases (DyPs; EC 1.11.1.19) were first purified and characterized in 1999, in the basidiomycete Bjerkandera adusta Dec 1 [1,2]
It was reported that Pleos-DyP4 shares catalytic properties with a versatile peroxidase enzyme (VP), while secretomic studies performed revealed that only the Pleos-DyP4 enzyme, as well as several VPs and MnPs, forms part of the P. ostreatus extracellular proteome during growth on lignocellulosic materials [7]
This study reports the differential expression of P. ostreatus dyp genes in a media supplemented with different dyes, the heterologous expression of the gene encoding DyP1 in Trichoderma atroviride, and its effect when applied to dyes
Summary
Dye-decolorizing peroxidases (DyPs; EC 1.11.1.19) were first purified and characterized in 1999, in the basidiomycete Bjerkandera adusta Dec 1 [1,2] They are heme peroxidases, and their name reflects their ability to degrade several anthraquinone dyes, with the heme group used as redox cofactor to catalyze the hydrogen peroxide-mediated oxidation of many kinds of molecules, including dyes. To date, these enzymes have been identified in the genomes of fungi, bacteria, and archaea, their physiological function is still unclear [3]. It was reported that Pleos-DyP4 shares catalytic properties with a versatile peroxidase enzyme (VP), while secretomic studies performed revealed that only the Pleos-DyP4 enzyme, as well as several VPs and MnPs, forms part of the P. ostreatus extracellular proteome during growth on lignocellulosic materials [7]
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