Biodegradation of lindane in soils using a dechlorinase produced by an actinomycete strain

CUOZZO, SERGIO; FUENTES, SOLEDAD; BENIMELI, CLAUDIA; AMOROSO, MAR¨ªA

Contaminated Soils: Environmental Impact, Disposal and Treatment.

Nova Science Publishers

Lugar: NUEVA YORK; Año: 2008;

There are many reports indicating that hexachlorocyclohexane (g-HCH) is present in soil, water, air, plants, agricultural products, animals, food, microbial environments and humans. Considered a potential carcinogen and listed as a priority pollutant by the US EPA, g-HCH is a lipophilic compound and therefore tends to accumulate and concentrate in the body fats of animals and humans. The g-HCH is an organochloride pesticide used in agriculture and medicine to world level. It has a big tendency to bioaccumulate into the environment and humans. In Sal¨ª River, Tucum¨¢n, Argentina lindane was detected 10- fold in relation to the traces permitted concentrations. The development of new technologies to remediate these sites using a specific enzyme is every time more necessary. The actinomycetes are Gram positive bacteria with great potential to bioremediate soil. Streptomyces sp. M7, was isolated from contaminated sediments with capacity to grow in presence of lindane as only carbon source and to remove it from a culture medium and soil samples.  It was detected, in this strain, for the first time an enzyme that can dechlorinate lindane, it is called dechlorinase. There are some reports regarding aerobic degradation of g-HCH by Gram-negative bacteria like Sphingomonas and by the white-rot fungi Trametes hirsutus, Phanerochaete chrysosporium, Cyathus bulleri and Phanerochaete sordida. However, little information is available on the ability of biotransformation of organochlorine pesticides by Gram positive bacteria and particularly by actinomycete species, the main group of bacteria present in soils and sediments. Since the toxicity of g-HCH is well established, it is imperative to develop methods by which lindane can be removed from the environment. It was demonstrated that Streptomyces sp. M7 possesses the LinA enzyme that catalyzes dehydrochlorination of ¦Ã-HCH to 1,3,4,6-tetrachloro-1,4-cyclohexadiene (1,4-TCDN) via ¦Ã-pentachlorocyclohexene (¦Ã-PCCH). The increase of ¦Ã-PCCH was detected in the time by GC. This strain can be useful to study the bioremediation capacity by dechlorinase from Streptomyces sp. M7 in soil contaminated with lindane.