Date of Award

8-1-2010

Degree Type

Thesis

University or Center

Clark Atlanta University(CAU)

School

School of Arts and Sciences

Degree Name

M.S.

Department

Biology

First Advisor

Dr. Godwin Ananaba

Second Advisor

Dr. Fisseha Abebe

Third Advisor

Dr. Victor Ibeanusi

Abstract

The recognition of the anti-microbial activity of oligodynamic metals such as silver has been a basis for the development of many antimicrobial processes and products. More specifically, silver and silver salts have been widely employed, particularly in water disinfection. Nano-sized silver particles have numerous commercial applications, including disinfection of water, food processing and disinfection of healthcare equipment. In Escherichia coli, which are vulnerable to silver, it has been suggested that the lipopolysaccharides on their surface contain high affinity binding sites for divalent cations. It has been shown that silver interacts with the cell membranes of bacteria, which alters their mesosomal functions, such as their ability to aid DNA replication. The nature of the bactericidal activity of silver and even more specifically silver impregnated alumina, its mechanistic details, and properties that influence disinfection are poorly understood. However, we hypothesize that silver impregnated alumina is an effective antimicrobial agent that could be used to improve water quality. To study this hypothesis, E. coil was exposed to various concentrations of metallic silver, impregnated on the surface of alumina and silver impregnated alumina’s effect in compromising bacterial cellular viability was determined. These studies reveal that E. coli exposure to concentrations of silver impregnated alumina results in decreased bacteria viability. Additionally, when calcination temperature and time are increased, a more effective catalyst is produced for antimicrobial activity. These studies also show that the silver impregnated alumina ability to kill bacteria is dose dependent, and that silver adsorption occurs upon contact with bacteria. Further, these studies show that silver is the active agent within the silver-alumina catalyst. Based upon this data, we believe that silver impregnated alumina is a more effective antimicrobial agent than silver nitrate solution.

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