HR: 0830h
AN: B21B-0707    [PDF]
TI: The Influence of Siderophores Produced by Alkaliphilic Microorganisms on Iron and Metal Contaminant Speciation and Solubility
AU: * Aiken, A M
EM: aaiken@wsu.edu
AF: WSU/NSF IGERT Center for Multiphase Environmental Research, Washington State University, P.O. Box 642719, Pullman, WA 99164-2719 United States
AU: Peyton, B M
EM: bmp@wsu.edu
AF: WSU/NSF IGERT Center for Multiphase Environmental Research, Washington State University, P.O. Box 642719, Pullman, WA 99164-2719 United States
AU: Petersen, J N
EM: jnp@wsu.edu
AF: Office of Research, Washington State Univeristy, P.O. Box 641033, Pullman, WA 99164-1033 United States
AU: Apel, W A
EM: waa@inel.gov
AF: Biotechnology Department, Idaho National Engineering and Environmental Laboratory, 2351 N. Boulevard P.O. Box 1625, Idaho Falls, ID 83415 United States
AU: Camper, A K
EM: anne_c@erc.montana.edu
AF: Center for Biofilm Engineering, Montana State University, 366 EPS Building PO Box 173980 Montana State University, Bozeman, MT 59717-3980 United States
AB: Halomonas campisalis strain 4A has been identified as capable of producing siderophores under halo-alkaliphilic growth conditions. Because of the scarcity of iron under the alkaline conditions in which Halomonas campisalis thrives, we hypothesize that the siderophores secreted by Halomonas campisalis and other alkaliphilic bacteria will have a stronger affinity for binding and solubilizing ferrous iron than siderophores produced by mesophilic bacteria. Siderophore production by Halomonas campisalis was confirmed through the use of the chrome azural S (CAS) agar plate method which showed a red orange halo around the bacterial colonies indicative of siderophore production. The siderophores were found to be produced under conditions of both high salinity and pH with a salt concentrations ranging from 0.4 - 1.8 M NaCl and pH ranging from 8 - 11. The siderophores produced have been determined to be of the hydroxamate class via the Cs ky method. A negative response to the Arnow assay indicated that the siderophore produced does not contain any catechol moieties in its chemical structure. It was found that maximum siderophore production was equivalent to approximately 400 mM desferrioxamine and occurred during mid stationary phase. Similar results were found at pH 8, 10 and 11. A purification scheme was developed that involved an initial extraction of the siderophore from the growth medium into benzyl alcohol followed by precipitation with diethyl ether. Additional purification was achieved via ion exchange chromatography and size exclusion chromatography. Final purification was achieved via HPLC. The structure of the purified siderophore was analyzed via LC/MS/MS equipped with an ESI source. To date, few studies have included the siderophores produced by microorganisms capable of tolerating highly saline and alkaline environments. In addition to unique structure and high affinity for iron, it is further hypothesized that siderophores from alkaliphilic bacteria will also have a corresponding higher affinity to heavy metal and radionuclide contaminants, thus increasing the mobility of these metals in subsurface environments and influencing contaminant fate and transport. Future work will examine the stability constants for complexes of various metals including uranium with the Halomonas campisalis siderophore.
DE: 0400 Biogeosciences
DE: 1615 Biogeochemical processes (4805)
DE: 4805 Biogeochemical cycles (1615)
DE: 4807 Chemical speciation and complexation
SC: Biogeosciences [B]
MN: 2003 Fall Meeting