Screening of organochlorine pesticides utilization by aquatic streptomycetes

CS BENIMELI; MJ AMOROSO; AP CHAILE; G OLIVER; G CASTRO

Orlando, Florida, USA

Congreso; American Society for Microbiology 101 General Meeting; 2001

American Society for Microbiology

Organochloride pesticides (PO) have been extensively used to protect the quality of food commodities, clothing and animal health and to combat diseases transmitted by insect vectors to man and animals. The persistence of their residues in the soil and their movement in the water-soil system are key aspects in their environmental behavior. The aim of this work was to investigate the ability of streptomycete aquatic strains to utilize some PO as unique carbon and energy source and their accumulation. Ninety-three actinomycete strains were isolated from a waste-water sediment of a mine plant located in a agricultural area of Tucumán, Argentina. Eleven PO: aldrin, chlordane, lindane, DDD, DDE, DDT, dieldrin, metoxichlor, heptachlor and their epoxides, were tested by qualitative assays in Starch Casein medium. Four actinomycete strains designed M4, M7, M9 and M15 were selected and identified by thin layer chromatography for isomeric diaminopimelic acid and whole-cell sugar composition. The growth of these strains was determined as dry weight  in a minimal medium with concentrations of aldrin, chlordane or lindane 5 to 50 mg l-1.  The growth and aldrin (48 mg l-1) uptake as unique carbon source was determined for M7 during 97 h in minimal medium. Residual aldrin was measured by Gas Chromatography. The four strains belonged to streptomycetes group. The microbial tolerance displayed 62 to 78 % according to the pesticide. The growth in minimal medium displayed enhanced or indifferent or inhibited relative growth profiles compared with medium supplemented with glucose. However, aldrin uptake by the four strains was increased concomitant with the pesticide concentration supplemented in the medium. Growth kinetic of M7 strain displayed exponential growth phase associated with fast decrease of pesticide concentration. When stationary growth phase reached at 96 h, less than 2.5 % aldrin residual concentration remained in the medium. The aldrin consumption was related to microbial growth, energy source and metabolism, until became toxic depending of each strain, but remained accumulated by the cells.