Use of Cadmium-Resistant Microorganisms in Co-contaminant RemediationEPA Grant Number: U914958
Title: Use of Cadmium-Resistant Microorganisms in Co-contaminant Remediation
Investigators: Roane, Timberley M.
Institution: University of Arizona
EPA Project Officer: Hahn, Intaek
Project Period: January 1, 1996 through January 1, 1999
Project Amount: $102,000
RFA: STAR Graduate Fellowships (1996) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Ecological Indicators/Assessment/Restoration , Fellowship - Earth Sciences
The objective of this study research project is to evaluate the ability of metal-resistant microorganisms to detoxify metal in co-contaminated (with both metallic and organic contaminants) systems to ultimately allow for organic degradation. This project addresses two questions:
(1) Can metal toxicity within a metal-contaminated soil be reduced by metal-resistant microbial populations?
(2) Will organic degradation occur in the presence of metal that was once bioaugmented with a microorganism capable of metal detoxification?
Using 2,4-D and cadmium as co-contaminants, several cadmium-resistant bacterial isolates were examined for the ability to detoxify cadmium to sufficient levels to allow for 2,4-D degradation to occur. Degradation of 500 mg Kg-1 2,4-D by the cadmium-sensitive 2,4-D degrading bacterium, Alcaligenes eutrophus JMP134, in the presence of cadmium occurred following cadmium detoxification by a cadmium-resistant isolate. The addition of one of four cadmium-resistant isolates, representing the genera Arthrobacter, Bacillus, and Pseudomonas, was found to detoxify up to 32 mg Kg-1 cadmium in pure culture and soil under laboratory and field conditions. Using genetic and microscopic analyses, the observed mechanisms of cadmium-resistance included: (1) slime layer production; (2) energy-dependent efflux; (3) surfactant production; and (4) intracellular accumulation.