Biodegradation of Fluoranthene by Basidiomycetes Fungal Isolate Pleurotus Ostreatus HP-1

Optimization of culture condition for enhanced decolorization and degradation of azo dye reactive violet 1 with concomitant production of ligninolytic enzymes by Ganoderma cupreum AG-1

The strain Ganoderma cupreum AG-1 (Genbank accession no. HQ328947) isolated from the decayed wood was evaluated for its ability to decolorize azo dye reactive violet 1 as well as for the production of ligninolytic enzymes. In the initial decolorization study, the strain was capable of decolorizing 19 different azo dyes. The strain was capable of decolorizing dye over a pH range of 4.5–6 at 30 °C. The optimum pH was found to be 4.5. Various other process parameters like additional carbon and nitrogen source and initial dye concentration were also optimized. The decolorization medium was supplemented with appropriate nitrogen source (yeast extract, 5 g l⁻¹) and carbon source (mannose, 2 g l⁻¹); the decolorization obtained was 98 %. The pattern of enzymes involved in the biodegradation was studied and laccase and MnP were found to be the major enzymes. High laccase activity shown by G. cupreum AG-1 and its ability to decolorize dyes are a good indication of its possible use in the treatment of textile effluents.

Biodegradation of oxytetracycline by Pleurotus ostreatus mycelium: a mycoremediation technique

Oxytetracycline (OTC) is administered in high doses to livestocks and enters the environmental compartments as a consequence of animal waste disposal. As a first step in setting up a useful mycoremediation technique, an OTC lab degradation test was performed in liquid medium using the ligninolytic fungus Pleurotus ostreatus. OTC disappearance in culture medium was clearly evident as early as the third day of exposure onwards, with an almost complete removal after 14d. The drug removal was mediated by fungal absorption in the mycelia, where the OTC molecule underwent a degradation step, as demonstrated by mass spectrometry analyses. A putative degradation product, ADOTC (2-acetyl-2-decarboxamido-oxytetracycline) is proposed. Experimental conditions excluded OTC abiotic degradation; the degradation by extracellular laccase was also experimentally discarded.

Biodegradation of tetrabromobisphenol A by oxidases in basidiomycetous fungi and estrogenic activity of the biotransformation products

Tetrabromobisphenol A (TBBPA) degradation was investigated using white rot fungi and their oxidative enzymes. Strains of the Trametes, Pleurotus, Bjerkandera and Dichomitus genera eliminated almost 1 mM TBBPA within 4 days. Laccase, whose role in TBBPA degradation was demonstrated in fungal cultures, was applied to TBBPA degradation alone and in combination with cellobiose dehydrogenase from Sclerotium rolfsii. Purified laccase from Trametes versicolor degraded approximately 2 mM TBBPA within 5 h, while the addition of cellobiose dehydrogenase increased the degradation rate to almost 2.5 mM within 3 h. Laccase was used to prepare TBBPA metabolites 2,6-dibromo-4-(2-hydroxypropane-2-yl) phenol (1), 2,6-dibromo-4-(2-methoxypropane-2-yl) phenol (2) and 1-(3,5-dibromo-4-hydroxyphen-1-yl)-2,2',6,6'-tetrabromo-4,4'-isopropylidene diphenol (3). As compounds 1 and 3 were identical to the TBBPA metabolites prepared by using rat and human liver fractions (Zalko et al., 2006), laccase can provide a simple means of preparing these metabolites for toxicity studies. Products 1 and 2 exhibited estrogenic effects, unlike TBBPA, but lower cell toxicity.