Potential of different white rot fungi to decolourize textile azo dyes in the absence of external carbon source

Fungal treatment of humic-rich industrial wastewater: application of white rot fungi in remediation of food-processing wastewater

This paper presents the results of fungal treatment of a real industrial wastewater (WW), providing insight into the main mechanisms involved and clarifying some ambiguities and uncertainties in the previous reports. In this regard, the mycoremediation potentials of four strains of white rot fungi (WRF): Phanerochaete chrysosporium, Trametes versicolor, Pleurotus ostreatus and Pleurotus pulmonarius were tested to remove humic acids (HA) from a real humic-rich industrial treated WW of a food-processing plant. The HA removal was assessed by color measurement and size-exclusion chromatography (SEC) analysis. T. versicolor showed the best decolorization efficiency of 90% and yielded more than 45% degradation of HA, which was the highest among the tested fungal strains. The nitrogen limitation was studied and results showed that it affected the fungal extracellular laccase and manganese peroxidase (MnP) activities. The results of the SEC analysis revealed that the mechanism of HA removal by WRF involves degradation of large HA molecules to smaller molecules, conversion of HA to fulvic acid-like molecules and also biosorption of HA by fungal mycelia. The effect of HS on the growth of WRF was investigated and results showed that the inhibition or stimulation of growth differs among the fungal strains.

Decolorization of Congo Red by Phanerochaete chrysosporium: the role of biosorption and biodegradation

The degradation of Congo Red by means of Phanerochaete chrysosporium BKM-F-1767 is reported in this work. Solid and liquid cultures have been prepared to evaluate in vivo biodegradation as well as the role of biosorption phenomena on mycelium. Moreover, in vitro tests have been performed to define the influence of MnP on dye decolorization. P. chrysosporium, cultivated on Malt Extract Agar in the presence of Congo Red 0.005% (w/v), has shown good growth and the ability to decolorize the dye in the 25-39°C temperature range. It has also been cultivated in a low NMM liquid medium with the aforementioned dye concentration in immobilized stationary cultures inducted for Lignin Peroxidase (LiP) and Manganese Peroxidase (MnP) production. Congo Red was absorbed on the biomass and then decolorized (93% and 85% for the LiP and MnP cultures, respectively). The cultures with added Congo Red have shown a higher MnP synthesis rate than a control without the dye. The enzymatic degradation of Congo Red has also been investigated by means of the extracellular fluid for different MnP activities (0-300 IU/l); the decolorization percentage has been found to be clearly related to the enzyme concentration up to a value of about 200 IU/l.

Biodegradation of naphthalenesulphonate polymers: the potential of a combined application of fungi and bacteria

The potential of several fungi and their synergy with bacterial biomasses were evaluated as a solution for the removal of 2-naphthalensulphonic acid polymers (2-NSAPs) from petrochemical wastewater, characterized by a chemical oxygen demand (COD) greater than 9000 mg/L. The ability of fungi to grow on 2-NSAP mixtures was preliminarily investigated using a solid medium, and then the action of the selected strains, both in suspended and immobilized form, was evaluated in terms of degradation, depolymerization, sorption and an increase in biodegradability of 2-NSAP. Among the 25 fungi evaluated two, in particular, Bjerkandera adusta and Pleurotus ostreatus, have been found to significantly depolymerize 2-NSAP yielding to the corresponding monomer (2-naphthalenesulphonic acid, 2-NSA), which has been further degraded by a bacterial consortia selected in a wastewater treatment plant (WWTP). The fungal treatment alone was able to reduce the COD value up to 44%, while activated sludge removed only 9% of the initial COD. In addition, the combined treatment (fungi and bacteria) allowed an increase in the COD removal up to 62%.