Valeria Prigione

Decolourisation and detoxification of textile effluents by fungal biosorption

Textile effluents, in addition to high COD, display several problems mainly due to toxicity and recalcitrance of dyestuffs. Innovative technologies effective in removing dyes from large volumes of effluents at low cost and in a timely fashion are needed. Fungi are among the most promising organisms for dye biosorption. In this study dye decolourisation, COD and toxicity decrease of three wastewater models after the treatment with inactivated biomasses of three Mucorales fungi cultured on two different media were evaluated. Fungal biomasses displayed good sorption capabilities giving rise to decolourisation percentages up to 94% and decrease in COD up to 58%. The Lemna minor toxicity test showed a significant reduction of toxicity after biosorption treatments, indicating that decolourisation corresponds to an actual detoxification of the treated wastewaters.

Scale-up of a bioprocess for textile wastewater treatment using Bjerkandera adusta

Twelve basidiomycetes were investigated for their ability to degrade 13 industrial dyes and to treat four model wastewaters from textile and tannery industry, defined on the basis of discharged amounts, economic relevance and representativeness of chemical structures of the contained dyes. The best degradation yields were recorded for one strain of Bjerkandera adusta able to completely decolourise most of the dyes and to decolourise and detoxify three simulated wastewaters, showing a significant physiological versatility which is very useful for application purposes. The effects of different nutrient sources were investigated in order to optimize the yields of decolourisation and detoxification. Manganese-peroxidase and manganese-independent peroxidase were the only recorded enzymatic activities. In order to evaluate its true bioremediation potential, this strain was packed in a fixed-bed bioreactor, for treatment of large volumes of a real wastewater. The fungus resulted effective during 10 cycles of decolourisation, remaining active for a very long period, in non-sterile conditions.

Chromium removal from a real tanning effluent by autochthonous and allochthonous fungi

Heavy metals represent an important ecological and health hazard due to their toxic effects and their accumulation throughout the food chain. Conventional techniques commonly applied to recover chromium from tanning wastewaters have several disadvantages whereas biosorption has good metal removal performance from large volume of effluents. To date most studies about chromium biosorption have been performed on simulated effluents bypassing the problems due to organic or inorganic ligands present in real industrial wastewaters that may sequestrate the Cr(III) ions. In the present study a tanning effluent was characterized from a mycological point of view and different fungal biomasses were tested for the removal of Cr(III) from the same tanning effluent in which, after the conventional treatments, Cr(III) amount was very low but not enough to guarantee the good quality of the receptor water river. The experiments gave rise to promising results with a percentage of removed Cr(III) up to 40%. Moreover, to elucidate the mechanisms involved in biosorption process, the same biomasses were tested for Cr(III) removal from synthetic aqueous solutions at different Cr(III) concentrations.

Decolorization and detoxication of reactive industrial dyes by immobilized fungi Trametes pubescens and Pleurotus ostreatus

Trametes pubescens and Pleurotus ostreatus, immobilized on polyurethane foam cubes in bioreactors, were used to decolorize three industrial and model dyes at concentrations of 200, 1000 and 2000 ppm. Five sequential cycles were run for each dye and fungus. The activity of laccase, Mn-dependent and independent peroxidases, lignin peroxidase, and aryl-alcohol oxidase were daily monitored during the cycles and the toxicity of media containing 1000 and 2000 ppm of each dye was assessed by the Lemna minor (duckweed) ecotoxicity test. Both fungi were able to efficiently decolorize all dyes even at the highest concentration, and the duckweed test showed a significant reduction (p ≤ 0.05) of the toxicity after the decolorization treatment. T. pubescens enzyme activities varied greatly and no clear correlation between decolorization and enzyme activity was observed, while P. ostreatus showed constantly a high laccase activity during decolorization cycles. T. pubescens showed better decolorization and detoxication capability (compared to the better known P. ostreatus). As wide differences in enzyme activity of the individual strains were observed, the strong decolorization obtained with the two fungi suggested that different dye decolorization mechanisms might be involved.

Pyrene degradation and detoxification in soil by a consortium of basidiomycetes isolated from compost: Role of laccases and peroxidases

A consortium of three basidiomycetes isolated from compost was investigated for pyrene degradation in soil microcosms. Pyrene concentration, glucose and ammonium evolution, moisture content, ligninolytic enzyme activities and phytotoxicity (germination index) on Lepidium sativum L. seeds were monitored. The fungal consortium grown on straw was found able to efficiently colonize soil and remove about 56 out of 100 mg kg(-1) of soil dry weight of pyrene in 28 days; in the meantime the germination index increased indicating a reduction of phytotoxicity. A glucose supply after 2 weeks was found useful to ensure fungal growth and activity; maintenance of moisture content below 70% allowed a good aeration of the system and improved degradation rates. Enzymatic assays showed that laccase and manganese independent peroxidase activity could have played a role in the degradation process.

Decolourisation and detoxification in the fungal treatment of textile wastewaters from dyeing processes

In this study a selected fungal strain, Bjerkandera adusta (Willdenow) P. Karsten MUT 3060, was tested in different culture conditions to assess its real potential for bioremediation of textile wastewaters in terms of both decolourisation and detoxification. The fungus efficiently decolourised (colour removal up to 96%) four simulated wastewaters that mimic the recalcitrance of real ones for pH values, concentration of dyes, additives and salts. In the culture condition with the lowest N content, the decolourisation was coupled with an important detoxification of two simulated effluents, underlining the important influence of the cultural medium composition not only on the degradation but also on the detoxification of industrial wastes. In the other cases, despite an extensive decolourisation, no detoxification was observed. The fungus was further tested against a real effluent, collected from a wastewater treatment plant before and after the tertiary treatment (ozonation) to compare the two technologies in terms of chemical and toxicological parameters. The fungal treatment, although less efficient than ozonation, caused a good decolourisation of the effluent, with colour values within the threshold limits of the Italian law; both the fungal and the ozone treatment caused a detoxification, but only towards one of the three organisms used for the ecotoxicological tests. These results underline the crucial importance of the ecotoxicological analysis in assessing the applicability of a wastewater treatment.

Integrated fungal biomass and activated sludge treatment for textile wastewaters bioremediation.

A combined biological process was investigated for effective textile wastewater treatment. The process consisted of a first step performed by selected fungal biomasses, mainly devoted to the effluent decolourisation, and of a subsequent stage by means of activated sludge, in order to reduce the remaining COD and toxicity. In particular, the treatment with Trametes pubescens MUT 2400, selected over nine strains, achieved very good results in respect to all parameters. The final scale-up phase in a moving bed bioreactor with the supported biomass of the fungus allowed to verify the effectiveness of the treatment with high volumes. Despite promising results, further steps must be taken in order to optimize the use of these biomasses for a full exploitation of their oxidative potential in textile wastewater treatment.

Development and Use of Flow Cytometry for Detection of Airborne Fungi

ABSTRACT Traditional methods for the enumeration of airborne fungi are slow, tedious, and rather imprecise. In this study, the possibility of using flow cytometry (FCM) for the assessment of exposure to the fungus aerosol was evaluated. Epifluorescence microscopy direct counting was adopted as the standard for comparison. Setting up of the method was achieved with pure suspensions of Aspergillus fumigatus and Penicillium brevicompactum conidia at different concentrations, and then analyses were extended to field samples collected by an impinger device. Detection and quantification of airborne fungi by FCM was obtained combining light scatter and propidium iodide red fluorescence parameters. Since inorganic debris are unstainable with propidium iodide, the biotic component could be recognized, whereas the preanalysis of pure conidia suspensions of some species allowed us to select the area corresponding to the expected fungal population. A close agreement between FCM and epifluorescence microscopy counts was found. Moreover, data processing showed that FCM can be considered more precise and reliable at any of the tested concentrations.

Industrial dye degradation and detoxification by basidiomycetes belonging to different eco-physiological groups

Twenty-five basidiomycetes belonging to 17 species and ascribable to different eco-physiological groups were screened for their ability to decolorize 9 commercially important industrial dyes comprising a variety of anthraquinonic, azoic and phtalocyanin chromophores. The influence of the culture medium, particularly its C:N ratio, on decolourisation capacity was considered on solid substrate. Three strains of Bjerkandera adusta performed the highest decolourisation yields being able to degrade all dyes on all media and to produce a wide spectrum of oxidative enzyme activities. Hence, B. adusta strains were selected for further experiments in liquid cultures together with other 6 fungi that resulted effective in the decolourisation of the largest number of molecules in the broadest spectrum of cultural conditions. Particularly B. adusta MUT 3060 was found very effective (decolourisation percentage over 90%) in the treatment of simulated effluents composed of single and mixed dyes at high concentration (1000 mg/l). Peroxidase activity dependent (up to 362 U/l) and independent from manganese (up to 57 U/l) were detected during the decolourisation process. The Lemna minor toxicity test showed a significant reduction of toxicity after the fungal treatment indicating that decolourisation corresponded to an actual detoxification of the wastewater.

Survey of ectomycorrhizal, litter-degrading, and wood-degrading Basidiomycetes for dye decolorization and ligninolytic enzyme activity

Basidiomycetes are essential in forest ecology, being deeply involved in wood and litter decomposition, humification, and mineralization of soil organic matter. The fungal oxidoreductases involved in these processes are today the focus of much attention with a view to their applications. The ecological role and potential biotechnological applications of 300 isolates of Basidiomycetes were assessed, taking into account the degradation of model dyes in different culture conditions and the production of oxidoreductase enzymes. The tested isolates belong to different ecophysiological groups (wood-degrading, litter-degrading, ectomycorrhizal, and coprophilous fungi) and represent a broad systematic and functional biodiversity among Basidiomycetes occurring in deciduous and evergreen forests of northwest Italy (Piedmont Region). The high number of species tested and the use of different culture conditions allowed the investigation of the degradation activity of several novel species, neglected to date. Oxidative enzyme activities varied widely among all ecophysiological groups and laccases were the most commonly detected enzymes. A large number of isolates (86%), belonging to all ecophysiological groups, were found to be active against at least one model dye; the wood-degrading fungi represented the most efficient group. Noteworthily, also some isolates of litter-degrading and ectomycorrhizal fungi achieved good decolorization yield. The 25 best isolates were then tested against nine industrial dyes commonly employed in textile industries. Three isolates of Bjerkandera adusta efficiently decolorized the dyes on all media and can be considered important candidates for application in textile wastewater treatment.