Arias, M. Y.. Scripps Institution of Oceanography-UCSD, Meriah@ucsd.edu
Obraztsova, A. Y.. Scripps Institution of Oceanography-UCSD, annao@ucsd.edu
Tebo, B. M.. Scripps Institution of Oceanography-UCSD, btebo@ucsd.edu

 
HEXAVALENT CHROMIUM REMOVAL BY SULFATE AND FACULTATIVE IRON-REDUCING BACTERIA ISOLATED FROM MARINE SEDIMENTS
 
Hexavalent chromium (Cr(VI)) at low levels (0.3 ppm) can cause serious inhibitory effects to many marine organisms. Sulfate-reducing bacteria (SRB) and iron-reducing bacteria (FeRB), are widespread in marine waters and sediments. Their activity leads to the production of hydrogen sulfide or ferrous iron, respectively, which can reduce Cr(VI) and bring about its detoxification. Some of these bacteria can also reduce Cr(VI) enzymatically. To further investigate the role of bacteria in Cr(VI) reduction, two stable anaerobic consortia, only one of which produced hydrogen sulfide, were obtained from metal-contaminated sediments and grown with varying concentrations of Cr(VI). Both consortia reduced 50 ppm Cr(VI) (~1mM) within 96 hours. The microbial composition of the consortia was investigated by denaturing gradient gel electrophoresis of ribosomal small subunit (16S) PCR products. Sequence analysis indicated that Desulfovibrio sp. was found in the sulfidogenic consortium whereas a Shewanella species, a facultative iron-reducing anaerobe, was present in both consortia. A pure culture of Shewanella species was isolated and found to reduce of 50 ppm Cr(VI) under sulfidogenic, Fe(III)-reducing, and aerobic conditions. Determining the mechanisms of Cr(VI) reduction by this isolate will lead to a better understanding of the role of bacteria in the natural attenuation of Cr(VI) pollution.
 
Day: Tuesday, Feb. 2
Time: Poster
Location: Sweeney Center
 
Code: SS06TU1098S