) is a pesticide that belongs to the group of organochlorines. It has beenextensively used since the Second World War all over the world and, even though its useis banned or restricted in many countries because of its deleterious effects, it is stillcommonly found in the environment, especially in the soil, due to its strong adsorption tosolid particles, which results in a great persistency (EPA, 1986). Some investigationshave reported that the DDT present in the soil can be degraded in two years, while othershave found that the process can take from fifteen to twenty years or more (Alexander,1994).The degradation products of DDT are mainly the dechlorination products DDE and DDD.The pathway can be DDT → DDE → DDD, or from DDT to DDD directly. These routeshave not been completely established, even after 40 years of studies (Wayland et al.,1991). In anaerobic marine sediments DDE is readily dechlorinated to DDMU (Quensenet al., 1998).In less developed countries, the use of DDT still continues in order to control diseasessuch as malaria and dengue (Wayland et al., 1991; Cebrian, 1998). So far, no chemicalcompound has been found that brings together DDT’s properties and effectiveness. InMexico, the use of DDT is higher than in any other Latin American country (PAHO,1994). Mexico used about 1000 tons of DDT in 1992 (Sharpe, 1995). The production ofDDT in Mexico is mostly for its own use. Though production has diminished since 1970,it has remained stable since 1985 (Lopez-Carrillo et al., 1996). In a study carried out inthe state of Veracruz in Mexico, DDT and DDE were determined in the adipose tissue ofpeople. These compounds were present in all the cases analyzed and the highest levelswere found in a suburban zone. Average DDT concentration was 24.82 mg/kg, veryhigh compared to the results in other countries (Waliszewski et al., 1995).In recent years, there has been renewed research interest in DDT, since it has beenassociated with several health problems, including the increased risk of breast cancer inwomen and alterations in reproductive functions in men (Cebrian, 1998).DDT is a chlorinated organic compound that is highly resistant to degradation bybiological, photolithical and chemical means, given that its molecular structure containschlorinated aliphatic and aromatic structures that impart great chemical stability.Because of this, DDT is a recalcitrant, toxic, persistent pollutant (Kannan et al., 1992).This explains the current interest in developing bioremediation processes for thiscompound.Current bioremediation processes typically use aerobic bacteria to degrade petroleum andother chemical wastes by oxidation of the compounds. However, it has been observedthat anaerobic systems are often more capable of degrading chlorinated pollutants byreductive dechlorination (Leahy and Brown, 1994). Some compounds, such aspolychlorinated biphenyls (PCBs) can be initially dechlorinated and partially degraded by