Betaproteobacteria dominance and diversity shifts in the bacterial community of a PAH-contaminated soil exposed to phenanthrene.

In this study, the PAH-degrading bacteria of a constructed wetland collecting road runoff has been studied through DNA stable isotope probing. Microcosms were spiked with (13)C-phenanthrene at 34 or 337 ppm, and bacterial diversity was monitored over a 14-day period. At 337 ppm, PAH degraders became dominated after 5 days by Betaproteobacteria, including novel Acidovorax, Rhodoferax and Hydrogenophaga members, and unknown bacteria related to Rhodocyclaceae.

Assessment of contaminated sediments with an indoor freshwater/sediment microcosm assay.

This study was conducted to assess the feasibility of using a 2-L, indoor microcosm assay to evaluate five contaminated sediments (A, B, C, D, and E). Toxic potential was deduced in the light of general contamination of sediments, pollutant partitioning in microcosms, and biological responses of species (Pseudokirchneriella subcapitata, Lemna minor, Daphnia magna, Hyalella azteca, Chironomus riparius): E > A > B > C > D. Sediments mainly were contaminated by metals (lead and zinc).

Stimulation of pyrene mineralization in freshwater sediments by bacterial and plant bioaugmentation.

As a means to study the fate of polycyclic aromatic hydrocarbons (PAHs) in freshwater sediments, pyrene mineralization was examined in microcosms spiked with [14C]pyrene. Some microcosms were planted with reeds (Phragmites australis) and/or inoculated with a pyrene-degrading strain, Mycobacterium sp. 6PY1.