Lindane removal using different supports for actinobacteria immobilization

SÁEZ, JULIANA MARÍA; BENIMELI, CLAUDIA SUSANA; AMOROSO, MARIA JULIA

Puerto Vallarta

Simposio; ISBA XVI 16th International Symposium on the Biology of Actinomycetes; 2011

Langebio CINVESTAV-IPN

Lindane is a persistent organochlorine insecticide widely used in developing countries. It has been classified by the United States Environment Protection Agency as a potent carcinogen and teratogen. One of the strategies adopted to remove lindane from the environment is bioremediation using microorganisms with degrading potential, such as actinobacteria. In addition, the use of immobilized microorganisms presents advantages over the free suspended cells, like their protection against toxicity and high degradation efficiency. The aims of this work were: 1) To evaluate the ability of pure cultures of streptomycetes, immobilized in four matrices, to remove lindane from a liquid medium, 2) To select the support which provides the optimal lindane removal for the pure cultures and 3) To evaluate the selected support for a mixed culture. The reuse ability of the immobilized cells was also tested. For this purpose, four previously isolated actinobacteria (Streptomyces sp. A2, A5, A11 and M7) were individually immobilized in four supports: agar cubes, PVA-alginate beads, silicone tubes and silk sachets. After 96 h of incubation in minimal medium added with lindane as carbon source, cell growth was estimated by determining the colony forming units per gram of matrix, and residual lindane concentration was determined in the culture supernatants by gas chromatography. The four actinobacteria individually immobilized in silicone tubes showed the highest growth values; however lindane removal by microorganisms was more efficient when they were immobilized in silk sachets (85-90% of removal). When the four strains were entrapped together in silk sachets, an improvement in lindane removal was not observed; nevertheless the sachets could be reused for two more cycles of 96 h, with a removal efficiency of 59% in each. The use of immobilized indigenous actinobacteria is a promising alternative for bioremediation of polluted sites, even though further studies about the use of mixed cultures will be necessary.