Differential expression of peroxidase and ABC transporter as the key regulatory components for degradation of azo dyes by Penicillium oxalicum SAR-3

Abstract

Fungal species are potential dye decomposers since these secrete spectra of extracellular enzymes involved in catabolism. However, cellular mechanisms underlying azo dye catalysis and detoxification are incompletely understood and obscure. A potential strain designated as Penicillium oxalicum SAR-3 demonstrated broad-spectrum catabolic ability of different azo dyes. A forward suppression subtractive hybridization (SSH) cDNA library of P. oxalicum SAR-3 constructed in presence and absence of azo dye Acid Red 183 resulted in identification of 183 unique expressed sequence tags (ESTs) which were functionally classified into 12 functional categories. A number of novel genes that affect specifically organic azo dye degradation were discovered. Although the ABC transporters and peroxidases emerged as prominent hot spot for azo dye detoxification, we also identified a number of proteins that are more proximally related to stress-responsive gene expression. Majority of the ESTs (29.5%) were grouped as hypothetical/unknown indicating the presence of putatively novel genes. Analysis of few ESTs through quantitative real-time reverse transcription polymerase chain reaction revealed their possible role in AR183 degradation. The ESTs identified in the SSH library provide a novel insight on the transcripts that are expressed in P. oxalicum strain SAR-3 in response to AR183.

Diverse Metabolic Capacities of Fungi for Bioremediation

“…A potential strain Penicillium oxalicum SAR-3 with broad-spectrum catabolic ability for different azo dyes possessed many novel genes for azo dye degradation which coded for ABC transporters and peroxidases along with stress-responsive genes. The occurrence of 183 unique expressed sequence tags (ESTs) was detected by a forward suppression subtractive hybridization (SSH) cDNA library of P. oxalicum SAR-3 in presence and absence of azo dye Acid Red 183 [148].…”

Azoreductase kinetics and gene expression in the synthetic dyes-degrading Pseudomonas

“…Biosorption on the cell wall due to the presence of different functional groups is one way to remove the dyes [16,25]. Another way is the enzymatically microbial degradation by the azodyecatabolic enzymes like azoreductase [26], laccase [27] and peroxidase [28]. Azoreductases of microorganisms are favorable for the development of biodegradation systems for azo dyes, because these enzymes catalyze reductive cleavage of azo groups (AN@NA) under mild conditions [29].…”