Indigenous actinomycetes useful in bioremediation process

POLTI M. A.,; BENIMELI C. S.; ALBARRACÍN V. H.; SIÑERIZ M.,; AMOROSO M. J.; ABATE C.M

Melbourne, Australia

Simposio; 13TH INTERNATIONAL SYMPOSIUM ON THE BIOLOGY OF ACTINOMYCETES.; 2003

ISBA

Human industrial wastes have produced widespread pollution of soils, groundwater, and marine environments. Bioremediation, the use of microbes to modify environmental contaminants, may be an effective biotechnological approach to clean up these environments. Actinomycete particular characteristics pose them as agents for bioremediation of contaminated soil. The aim of this work is to introduce Argentinean soils actinomycetes, as potential useful tools to perform bioremediation processes in environments polluted with lindane and heavy metals as chromium, cadmium and copper. Sediment samples were collected from different soils of Argentina. Isolation of actinomycetes was performed using selective media. Qualitative and semiquantitative analysis of inhibition by heavy metals were carried out in plates containing MM agar medium and solutions of K2Cr2O7 CuSO4 and CdCl2 . Previously selected copper (ABO), chromium (Streptomyces R22) and cadmium (Streptomyces R25) resistant strains were grown in media supplemented with metal solutions. Streptomyces M7, previously isolated,  was grown in MM medium added with lindane. Washed cells were inoculated in MM medium with glucose  and 6 and 20 h after starting the incubation, lindane was added. Seventy colonies of actinomycetes were isolated. Measures of growth showed very low incidence (4.3%) of resistance to the highest Cu++ concentration tested (320 ppm). The incidence of resistance to Cr(VI) 260 ppm and Cd++ 100 ppm was 35 and 30% respectively. Streptomyces R22, showed a growth of 75% in presence of Cr (VI) 50 ppm respect to the control and the Cr(VI) concentration in the supernatant of the culture diminished 45% at 7 days of incubation. ABO,  was capable of growing in presence of Cu++ 80 ppm like the control in MM liquid medium. Streptomyces R25, was chosen as the most suitable strain to perform cadmium bioremediation assays in liquid Soil Extract because of its Cd fixing capacity. Streptomyces M7, could grow until 48 h of incubation using glucose as the only carbon source. Beyond this time, a decrease of lindane concentration in the supernatant was observed. When lindane was added at 6 h and  20 h of incubation the lindane removal was 22 % and 74 % respectively.