Biodegradation of phenol by Antarctic strains of Aspergillus fumigatus.

The capability of Antarctic microorganisms, including fi lamentous fungi, to exist in some of the most severe climatic conditions known on earth, such as extremely low temperatures and poor availability of nutrients, is the cause of increasing interest in their metabolism. The study of species diversity characteristics of this region and the organisms’ metabolic capabilities can provide new solutions for industry and environment. Many strains isolated from this area which is characterized by very low temperatures are psychrotrophs (growth temperatures from 15 to 20 °C), and only a few of them are true psychrophiles (Margesin et al., 2003, 2005; Tosi et al., 2010). Phenol and its various derivatives, as well as many other aromatic compounds, are known as some of the most hazardous pollutants (Smith et al., 1988; Sikkema et al., 1995). Many phenolcontaminated environments are characterized by low temperatures. With this in mind, the microorganisms adapted to growth in these conditions might play an important role in the bioremediation of such polluted habitats (Margesin et al., 2005). Most of the published investigations on the degradation of phenol were performed with strains of bacteria and also of some yeasts ( Pakula et al., 1999; Alexieva et al., 2008; Nair et al., 2008; Chakraborty et al., 2010). Some strains of hyphal fungi, such as Fusarium, Graphium, and Aspergillus, have been cited for their potential for phenol degradation (Anselmo et al., 1985; Santos and Linardi, 2004; Krastanov et al., 2009; Yemendzhiev et al., 2009). Many moulds have been isolated from soil probes taken in Antarctica, and many of them demonstrated good tolerance to the presence of toxic phenolic compounds in their culture medium (Aislabie et al., 2006; De Domenico et al., 2004; Alexieva et al., 2011). The effi cient degradation and utilization of toxic environmental pollutants, such as phenol, depends on the availability and activity of some key enzymes in the microbial cells. The fi rst step in the aerobic metabolism of phenol is its ortho-hydroxylation to catechol by phenol hydroxylase. Catechol is a central intermediate in the degradation pathways of various aromatic compounds; it is metabolized by different strains via either the orthoor meta-cleavage pathway (Neujahr and Varga, 1970; Reardon et al., 2000; Stoilova et al., 2006; Pradhan and Ingle, 2007). The ortho-mechanism has been Biodegradation of Phenol by Antarctic Strains of Aspergillus fumigatus