Screening of wood rotting fungi potentially useful for the degradation of organic pollutants

Many papers have shown that white rot fungi can degrade aromatic pollutants under laboratory conditions, but few report field scale trials. Here we report the first steps in the development of a remediation system for Greek conditions. A review of the available organochlorine compound pollution information in Greece is presented. White rot fungi isolated from sites in Greece have been screened for growth rate and ligninolytic activity, using decolourisation of the dye Poly R-478 as an indicator of enzyme activity. Use of white rot fungi under field conditions in Greece will require bioaugmentation to be effective at high temperatures and low water activity for much of the year. The most potent strains have been selected under a range of conditions and have been challenged with priority pollutants to determine their degradative ability under laboratory conditions and subsequently ex situ in soil.     

Trace Metals in Different Crop/Cultivation Systems in Greece

Typical soils in Greece are neutral or alkaline and frequently are lime-rich, conditions that favour the accumulation of trace elements. The traditional use of metal-based fungicides in orchards and vineyards may have led to the accumulation of trace metals. Concentrations of Fe, Cu, Mn, Zn (aqua regia digestion) and some other soil parameters were measured in organically and conventionally cultivated soils (0–30 cm) from vineyards, olive groves and citrus groves of varying ages, and in uncultivated soils. Many vineyards and olive groves are situated in hilly or mountainous areas with sloping ground or terraces in contrastto citrus, which is cultivated in lower lying areas. Due to the difficulty of access, these crops often are cultivated extensively in both systems. Trace metal concentrations were found to lie withinthe ranges expected for the predominant soil types. Cu concentrations were relatively high (>100 mg kg^-1) in a few samples, but were not correlated with the age of the cultivation. A two-way ANOVA analysis showed larger differences in the mean concentrations of Cu, Mn and Zn between different crops (p≤ 0.001 for Cu, p≤ 0.05 for Zn, and p≤ 0.1 for Mn) than between different cultivation systems (no significant differences). The crop by cultivation interaction was not statistically significant for any metal (p > 0.8). Strong correlations (p≤ 0.001) were found between Fe, Mn and Zn and both clay concentration and CEC, although these relationshipswere not uniform throughout the different crop and cultivation systems. Concentrations of Cu were related to clay concentrations only for vineyards and to CEC only for citrus. Correlations were not found with organic matter or pH.     

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.