THE VIRGINIA ACADEMY OF SCIENCE
Virginia Journal of Science


Virginia Journal of Science. 2002.  Vol 53 (3) : 141-155
Chromium Tolerant Microbial Communities from the Chesapeake Bay Watershed
Kristine L. Lowe1, Ruth E. Fliflet1, Tony Ly1, Brenda J. Little2 and Joanne Jones-Meehan1, 1Chemistry Division, Code 6115, Naval Research Laboratory, Washington, DC 20375 2Oceanography Division, Code 7303, Naval Research Laboratory, Stennis Space Center, MS 39529.

ABSTRACT
Chromium tolerant bacteria were enumerated from portions of the Chesapeake Bay watershed and examined for their potential to reduce Cr(VI). Water and sediment samples were collected from various locations in Baltimore Harbor and Bear Creek, as well as Sandy Point State Park in Maryland and the Anacostia River in Washington, DC. Samples were spread onto agar plates with CrO42- (5 ppm) as the sole terminal electron acceptor. Plates were incubated anaerobically and colony forming units (CFU) enumerated. CFU arising on minimal-CrO42- medium ranged from 103-104 mL-1 or g-1 and community estimates from sites in proximity to Baltimore City were approximately 6-30X higher than distal sites. Bacterial identification by BIOLOG™ or 16S rRNA sequencing indicated the presence of bacteria of the genera Klebsiella, Pseudomonas, Burkholderia, Kluyvera and others. Typical Cr(VI) reduction rates by these isolates were significantly lower than Shewanella oneidensis, a known metal-reducing bacterium. Results suggested that microbial communities in the Chesapeake Bay watershed, particularly in Baltimore Harbor and Bear Creek, had a high tolerance for Cr(VI) and/or could grow slowly with Cr(VI) as a terminal electron acceptor. However, the isolates did not rapidly degrade Cr(VI) in the laboratory.

Key Words: Chromium tolerance, Shewanella, contaminant metals, Chesapeake Bay