Ecotoxicological effects of decabromodiphenyl ether and cadmium contamination on soil microbes and enzymes

The ecotoxicological effects of decabromodiphenyl ether (BDE209) and cadmium (Cd) contamination on soil culturable microbial population, enzyme activity and bacterial community structure were investigated. Results of the indoor incubation test runs performed on many series of control and contaminated soil samples have demonstrated some notable toxic effects due to long term exposure to either or both contaminants. The two contaminants produced notable yet different toxic effects on the test microbes; the population of the exposed species generally declined according to certain dose–response relationships. The soil culturable microbial population and enzyme activity data show that the sensitivity to one or both contaminants followed the order of: bacteria>fungi>actinomycete and urease>saccharase, respectively. The interaction between BDE209 and Cd was dependent on both the exposure dose and time and that the joint toxic effects were synergistic, antagonistic or additive. The PCR-DGGE analysis data of species composition and richness suggest the synergistic combined effects on bacterial community structure during the 30d exposure. Pseudomonas tuomuerensis strain CCM 7280 and Pseudomonas alcaliphila strain AL15-21 were enriched, indicating these species might be major functional populations and highly tolerant. Such observations have provided the useful information of potential ecotoxicological effects of BDE209 and Cd contamination in the environment. ► Two contaminants produced notable yet different toxic effects on the test microbes. ► The sensitivity followed the order: bacteria>fungi>actinomycete or urease>saccharase. ► The interaction was dependent on both the exposure dose and time. ► DGGE analysis showed the synergistic toxic effects on bacterial community structure. ► Pseudomonas tuomuerensis strain CCM 7280 and alcaliphila strain AL15-21 were enriched.