Restauración de suelos contaminados por medio de procesos microbiológicos y enzimáticos

Abstract

In the last years, a high number of highly toxic compounds have been released into theenvironment because of several industrial and/or agricultural activities. Typical organicchemicals include pesticides, fuels, solvents, alkanes, polycyclic aromatic hydrocarbons(PAHs), nitrogen and phosphorus compounds, explosives, and dyes while inorganiccontaminants are mainly represented by toxic heavy metals.Contamination of soil, surface and ground water by organic pollutants is a problem ofgreat environmental concern in several countries. Furthermore, a complex pollution includingmore than one pollutant and also toxic metals may accumulate in the environment thusbeing a point of major concern for both a toxicological risk assessment of contaminatedfield sites and to study the feasibility of bioremediation technologies to remediatecontaminated soils.Intrinsic biodegradation is one of the natural attenuation phenomena, which may occurat the contaminated soil and contribute to its remediation (Figure 1). Indeed, most of pollutingchemicals have been proven to be transformed by microbial organisms (Alexander, 1985;Cerniglia, 1992; Alexander, 1994). Their susceptibility to biodegradation may, however,change drastically, depending on several factors related to the chemical and physicalproperties of both the chemical and the environment in which they are present.Although much experimental evidence supports the capability of microorganisms tobiodegrade organic pollutants, several sites are still strongly contaminated, indicating ahigh persistence of these compounds under field conditions.Several strategies have been devised to remediate and restore polluted environments:physical and chemical methods and biological approaches, requiring the involvement ofbiological agents (Adriano et al., 1999; Alexander, 1985, 19994; Bollag and Liu, 1990; Bollagand Bollag, 1995; Bouwer and Zender, 1993; Cerniglia, 1992; Edgehill, 1999; Edgehill et al.,1991,Gevao et al., 2000;