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Swanson, Juliet S.

Publications and source records attributed to Swanson, Juliet S..

6 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Effects of Salt Concentration, Ionic Strength, and Water Activity on the Growth of a WIPP Archaeal Isolate, Halobacterium sp.

An extremely halophilic archaeon (Halobacterium sp., WIPP strain), isolated from WIPP halite, was tested for its ability to grow in media containing various combinations of sodium and magnesium chloride that influenced overall ionic strength and water activity. Halobacterium sp. grew well in most tested salt combinations, and its growth appeared to depend more upon the relative contribution of sodium to overall ionic strength than on other parameters. Growth rates were highest when media consisted of at least 2 M NaCl and lowest when NaCl dropped below 20% of the ionic strength (usually less than 0.5 M). High magnesium concentrations (1 and 1.5 M MgCl 2 ) did not prevent Halobacterium sp. growth, as long as the sodium contribution was sufficient. Water activity was not a definitive factor in determining growth, because this value did not reach an extreme lower limit in the experimental media.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Biomass and salt-dependent effects of Bacillus spores on radionuclide migration from the Waste Isolation Pilot Plant

Spores of a Bacillus sp., isolated from radioactive waste, were tested for their ability to influence the fate and transport of neodymium (Nd3+) under high salt conditions expected at the Waste Isolation Pilot Plant (WIPP) nuclear waste repository. Spores were suspended in neodymium-spiked saline solutions up to 4 M NaCl, and concentrations of Nd and the complexing agent dipicolinic acid (DPA), a component of spores, were monitored along with optical densities and spore numbers. Overall, results support neodymium bioassociation that is dependent upon biomass, with more apparent adsorption occurring at higher spore concentrations. However, probable spore lysis in 2 and 4 M NaCl solutions and possible germination at 0.15 M NaCl appear to drive the release of DPA and subsequent return of Nd to solution. The implications of this work for the WIPP will depend on actual biomass levels and the ionic strength of the repository brines.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗