No abstract

46 actinomycetes were isolated from two polluted sites and one unpolluted site. One strain, F4, was selected through primary qualitative screening assays because of its cadmium resistance, and physiologically and taxonomically characterized. F4 was able to grow at 7.5% NaCl and 100 microg/ml lysozyme and at a pH between 6 and 10. 16S rDNA sequence analysis showed that F4 was closely related to Streptomyces tendae. Growth of Streptomyces sp. F4 on culture medium with 8 mg/l Cd(2+) for 8 days showed 80% inhibition. Maximum specific biosorption was 41.7 mg Cd(2+)/g dry weight after 7 days of growth and highest Cd(2+ )concentration was found in the cell wall (41.2%). The exopolysaccharide layer only contained 7.4%, whereas 39.4% of Cd(2+) was found in the cytosolic fraction. Twelve % was found in the ribosomes and membrane fraction. This was verified with TEM, showing Streptomyces sp. F4 cytoplasm with dark granulate appearance. This study could present the potential capacity of Streptomyces sp. F4 for Cd(2+) bioremediation.

To gain insight into mechanisms controlling ecosystem regeneration, we investigated a grassland that was heavily polluted by a phosphate fertilizer factory between 1960 and 1990. Abiotic and biotic filters that influenced species assemblage and succession were monitored and restoration approaches assessed. Studies included the investigation of soil parameters, impact of abiotic stress on microbes and plants, plant succession, recolonization mechanisms, functional group interactions, mycorrhizal diversity and function, and food web analysis. Results indicate that after cessation of pollution, the system had high potential for self-recovery. About 15 years of research are now summarized by interrelating the results of all projects and fitting them into one conceptual model.