Date of Award


Document Type


Degree Name

Master of Science


Department of Engineering Physics

First Advisor

Larry W. Burggraf, PhD


This research was a general phenomenalistic overview of the effects of metals on the respiration rates of a toluene selected microbe culture. The metals studied were copper, zinc, cobalt, manganese and iron. Relative inhibition, Cu>Fe>Zn=Co>Mn, corresponded to hydrogen phosphate binding strengths. Inhibition was found to be pH dependent; it increased with increasing pH and was shown to correlate to an increased adsorption of metal onto the cell. Zn, Cu, and Co toxicities were shown to decrease with increasing magnesium concentrations. This decrease was linked to increased magnesium adsorption and decreased metal adsorption. The magnitude of effect was related to Mg competitiveness. Sterile plating techniques were used to determine metal lethality. Results did not correspond to respiration results; however, it was demonstrated that copper's effect was lethal while zinc's was inhibitory. Increasing metal concentrations cause toxicity to increases at a decreasing rate only so long as the metal remains in solution. Metals as precipitates are no longer available to adsorb to the cell and do not affect toxicity. Toxicity was shown to be related to metal availability and how well it competed with other cations. Toxicity also depended on cell-ligand competition and how strongly the metal bound itself to the cell.

AFIT Designator


DTIC Accession Number



Alternative designator found on title plate: AFIT-GEE-ENV-95D.