Differential regulation of Pleurotus ostreatus dye peroxidases gene expression in response to dyes and potential application of recombinant Pleos-DyP1 in decolorization

摘要

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.