Date of Award

Fall 2004

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemistry & Biochemistry

Program/Concentration

Chemistry

Committee Director

Roy L. Williams

Committee Member

Mark S. Elliot

Committee Member

Robert Dias

Call Number for Print

Special Collections LD4331.C45 F38 2004

Abstract

Chlorine became a major disinfectant for the removal of microbial contaminants in 1914. Current water chlorination procedures yield halogenated disinfection byproducts (DBPs), such as haloalkanes and haloacetic acids (HAAs), due to the reaction of chlorine with naturally occurring organic compounds. Various water utilities have observed decreased HAAs levels in maximum residence time locations (MRTLs), where they were expected to be higher. These MRTLs have low free chlorine residual and high heterotrophic bacteria plate counts. Xanthobacter autotrophicus, GJ-10, is a bacterium that has been shown to contain dehalogenase enzymes and, therefore, can biodegrade HAAs. A number of water-system bacteria were identified and are being studied for their involvement in enzymatic degradation of DBPs in the distribution systems. Two bacteria, Novosphingobium aromaticivorans and a Burkholderia species, were isolated from a Newport News Waterworks MRTL, and have been shown to degrade HAAs. A colorimetric assay was implemented to screen the bacteria for dehalogenase activity. This assay consists of dichloroacetic acid (DCAA), pH indicator, and phenol red, which are integrated into the growth medium. The bacteria that have an active dehalogenase enzyme will initiate degradation of the DCAA causing an increase in the chloride ion present and a decrease in pH due to HCl formation. This change in pH causes the red dye in the media to become yellow. This colorimetric assay was further implemented in order to determine the activity of the dehalogenase enzymes during various enzyme purification steps. This thesis will describe research results regarding the dehalogenase enzyme isolation, purification and kinetic analysis.

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DOI

10.25777/yvny-jz65

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