Abstract
Thirty six (36) native fungal strains from the state of Yucatan were first screened for ligninolytic activity on solid media containing ABTS. Molecular identification based on ITS rDNA region and PCR fingerprinting of seven selected fungi isolates werecarried out. Molecular characterization based on genetic fingerprinting was helpful in determining unequivocally the differences between isolates at genera and species levels. The seven isolates showed ABTS oxidation zones in plates but only five strains produced extracellular laccase. The strains identified as Trametes hirsuta(GenBank accession numbers GQ280372 and GQ280373) showed the highest laccase production. The strain Bm-2 displayed the greatest laccase activity and dye decolourization ability in 72 h without the addition of mediators. Both the high laccase activity shown by Bm-2 and its ability to decolorize dyes are a good indication of its possible use in the treatment of textile effluents. Key words: Laccase, Trametes hirsuta, dye decolorization, PCR fingerprinting.
Highlights
Biological processes represent a good alternative for remediation and decontamination of environmental pollutants given the ability of some microorganisms to mineralize a wide variety of toxic xenobiotics and to oxidise substrates with low solubility, such as chlorinated phenolics, synthetic dyes, pesticides and polycyclic aromatic hydrocarbons (Baldrian, 2006; Reddy, 1995; Rodriguez et al, 1999; Torres et al, 2003)
Molecular identification based on internal transcribed spacer (ITS) rDNA region and PCR fingerprinting of seven selected fungi isolates were carried out
In the search for fungi strains well adapted to the environmental conditions of the region and with high laccase activity to be used in effluent decontamination, the aim of this study was to screen selected Yucatan native fungi for their ability to decolourize effluent and textile dyes and to carry out the molecular characterization of these fungi
Summary
Biological processes represent a good alternative for remediation and decontamination of environmental pollutants given the ability of some microorganisms to mineralize a wide variety of toxic xenobiotics and to oxidise substrates with low solubility, such as chlorinated phenolics, synthetic dyes, pesticides and polycyclic aromatic hydrocarbons (Baldrian, 2006; Reddy, 1995; Rodriguez et al, 1999; Torres et al, 2003). White-rot fungi including Trametes, Pleurotus, Coriolopsis and other genera, degrade a variety of dyes without generating toxic by-products. Studies on these organisms have identified laccase as a significant component of their enzyme system (Levin et al, 2004; Peláez et al, 1995). Identification and characterization of fungi species and strains is based on morphological, physiological, biochemical and genetic characteristics. DNA-based identification is faster and more reliable than phenotypic characterization (Kurtzman et al, 2003). Appropriate molecular methods for identification of fungi species and strains are PCR-fingerprinting, RAPDs and restriction analysis of non-coding ribosomal DNA (rDNA) (PCR-RFLP of internal transcribed spacer [ITS]), cleaved amplified polymorphic sequence and simple sequence repeats (SSRs). The efficacy of identification can be greatly increased when combinations of these methods are used
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