Abstract
Rhizoremediation, one of phytoremediation strategy, restores polluted site using collaborating interactions between plants and rhizosphere microbes. In order to enhance the remediation activity, many researches to introduce pollutant-degrading microbes into rhizosphere have been extensively implemented. Most of the researches have been targeting the terrestrial plants, while there is a little information about that in aquatic plants. In present study, 11 strains derived from the rhizosphere of giant duckweed (Spirodela polyrrhiza) were used, and we aimed to screen suitable microbes for introduction into rhizosphere of S. polyrrhiza in terms of root periphytic property and rhizosphere survivability. We investigated which microbes could attach tightly to the roots and dominate in microbial community of 11 strains inhabiting the rhizosphere of sterilized S. polyrrhiza. As a result, Asticcacaulis sp. strain RS59G dominated in the microbial community of 11 strains, and the strain had high root periphytic property. Survivability of 3 strains in the rhizosphere of S. polyrrhiza was evaluated using recombinants of the each strain in the presence of competition between the recombinants and environmental microbes. All of the recombinants inhabited stably in the rhizosphere of S. polyrrhiza, and Asticcacaulis sp. strain RS59G maintained large population in the rhizosphere for 3 days. These results suggest that introduction of pollutant-degrading microbes into rhizosphere of aquatic plants could be promising strategy for aquatic environmental purification.
