Isolation of four aquatic streptomycetes strains capable of growth on organochlorine pesticides

Ninety-three wild-type isolates identified as actinomycetes were tested against 11 organochlorine pesticides (OPs): aldrin, chlordane, DDD, DDE, DDT, dieldrin, heptachlor, and heptachlor epoxides, lindane, and methoxychlor. Qualitative screening agar assays displayed 62–78% tolerance of strains to OPs. Four strains designed M4, M7, M9 and M15 were selected based on multi-OPtolerance, and identified as members of the streptomycetes group. Different growth profiles were observed in cultures of the four selected streptomycetes cultured in synthetic medium containing 5–50 lg l 1 aldrin or chlordane or lindane. Increase of aldrin removal by the selected microorganisms was concomitant with the 4.8–36.0 lg l 1 pesticide concentration range. After 72 h of streptomycete M7 growth in synthetic medium containing 48.0 lg l 1 aldrin, the remaining OPconcentration in the supernatant was approximately 10% of the initial concentration. Also, in stationary growth phase less than 2.5 lg l 1 aldrin residual concentration was detected in the medium.