Characterization of a fungal strain isolated from a polyphenol polluted site.

A group of fungal strains were isolated from a polyphenol polluted soil, taken from an olive oil processing plant in Attica, Greece. The fungi were tested for their ability to decolorize a polyaromatic dye Poly R-478, which was used as a model compound to test their ligninolytic activities. The strain K1.1 decolorized efficiently the dye on agar plates and was further studied. PCR amplification of the internal transcribed spacer (ITS) region of the ribosomal RNA genes from the genomic DNA isolated from mycelium grown in liquid culture resulted in amplified fragments. Via BLASTN search, the length of a 773 base pairs was identified as the basidiomycetes Coprinellus xanthothrix. The growth rates and the tolerance of the fungus were compared on solid media, containing four different concentrations of pentachlorophenol. Extracellular enzyme activities (lignin peroxidase, manganese peroxidase and laccase) were determined in defined liquid medium. The isolate expressed laccase and manganese peroxidase but not lignin peroxidase. The removal of the dye was also estimated in liquid medium. The fungus showed biosorption and biotransformation as removal mechanisms.

Bioremediation of a soil contaminated by lindane utilizing the fungus Ganoderma australe via response surface methodology.

Mixtures of a sandy soil and wheat straw were doped with the organochlorine insecticide lindane in glass tubes and were inoculated with the polypore fungus, Ganoderma australe. An evaluation of bioremediation process effectiveness was searched and five parameters identified for the solid-state system. Fungi growth is a function of temperature and requires moisture for a proper colonization. These microorganisms need inorganic nutrients such nitrogen and phosphorus to support cell growth and it is also appropriate to know the range of concentration and toxicity of the used insecticide. Thus, an orthogonal central composite design (CCD) of experiments was used to construct second order response surfaces. Five design factors, namely temperature, moisture, straw, lindane content and nitrogen content and seven optimization parameters (responses), namely lag time, propagation velocity, biomass growth rate, biodegradation rate, biodegradation/biomass, biomass/propagation and biomass content were analyzed. The optima of the responses of the adequate models were found to be the following: propagation velocity 4.25mm/day, biomass growth rate 408mg/day, biodegradation/biomass 56.9microg/g, biomass/propagation 250mg/mm and fungal biomass content in solid mixture 260mg/cm(3). The most important response for bioremediation purposes is biodegradation/biomass which is maximized at the factors levels: temperature 17.3 degrees C, moisture 58%, straw content 45%, lindane content 13ppm and nitrogen content 8.2ppm.

Biodegradation of lindane by Pleurotus ostreatus via central composite design.

The degradation of lindane was studied in liquid-agitated cultures using a commercial strain of the fungus Pleurotus ostreatus as the biodegrading organism. The biodegradation was accomplished with the action of extracellular oxidative enzymes, produced by the fungus to decompose woody substrates. Enzyme activities of manganese peroxidase and laccase were measured in a liquid mineral medium. An orthogonal Central Composite Design of experiments was used to construct second-order response surfaces with the fungus growth, final pH and the lindane biodegradation as optimization parameters. The initial lindane concentration, the nitrogen content, the incubation time and the temperature were used as design factors. Optimal conditions found for all these parameters will be used for the continuation of this project aiming at the bioremediation of contaminated sites with persistent organic pollutants such as lindane.