HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (6) Citing Articles via Google Scholar Google Scholar Articles by Azaizeh, H. A. Articles by Emons, H. Search for Related Content PubMed PubMed Citation Articles by Azaizeh, H. A. Articles by Emons, H. GeoRef GeoRef Citation Agricola Articles by Azaizeh, H. A. Articles by Emons, H. Related Collections Wetlands and Aquatic Processes Soil Microbiology Bioremediation and Biodegradation Heavy Metals Industrial Waste

TECHNICAL REPORTS
Bioremediation and Biodegradation

The Potential of Rhizosphere Microbes Isolated from a Constructed Wetland to Biomethylate Selenium

^a Research and Development Center, The Galilee Society (affiliated with Haifa University), P.O. Box 437, Shefa-Amr 20200, Israel
^b Institute of Phytospheric Research, Research Center Juelich, 52425 Juelich, Germany

* Corresponding author (hazaizi{at}gal-soc.org)

Received for publication February 12, 2002. The potential of rhizosphere microbes isolated from common reed [Phragmites australis (Cav.) Trin. ex Steud] plants grown in a subsurface-flow constructed wetland to biomethylate selenate or selenite was studied in liquid cultures under controlled conditions. Total mean percentages of volatilized Se from half-strength Hoagland culture solutions (low C content) supplemented with selenate or selenite and inoculated with cultured rhizosphere microbes after 15 d of incubation were 7.9 and 49.1%, respectively. There was a relative best fit (r = 0.87) between total number of rhizosphere and cultured microbes and the percentage of volatilized Se in Hoagland solution after 15 d of incubation. However, when the same microbes were cultured in tryptic soybean broth (TSB) medium (high C content), the percentages of volatilized Se from selenate and selenite were 1.3 and 1.9%, respectively. The volatilization percentages of Se from selenate or selenite in culture solutions inoculated with rhizosphere suspension instead of cultured rhizosphere microbes were very low (1.2–3.0%) in both cultivation media. In all experiments, selenite was volatilized significantly (p < 0.05) in higher amounts by cultured rhizosphere microbes after 15 d of incubation compared with selenate. Dissolved biomethylated dimethylselenide (DMSe) in water samples taken from the subsurface-flow bed was determined by purging with helium. The DMSe in water samples was indirectly detected up to 2.4 µg Se L^-1, which indicates that part of the produced DMSe was dissolved in the matrix before being released into the atmosphere. Our results show that rhizosphere microbes isolated from common reed plants have a high potential of Se biomethylation and volatilization from selenate and selenite.

Abbreviations: AMVF, aquatic microcosm vegetation facility • CFU, colony forming units • DMDSe, dimethyldiselenide • DMSe, dimethylselenide • HG–AAS, hydride generation–atomic absorption spectrometry • ICP–MS, inductively coupled plasma–mass spectrometry • TSB, tryptic soybean broth