Date of Award

12-2000

Degree Name

Master of Science

Department

Biological Sciences

First Advisor

Dr. Silvia Rossbach

Second Advisor

Dr. Bruce Bejcek

Third Advisor

Dr. Robert Eisenberg

Access Setting

Masters Thesis-Open Access

Abstract

Genes responsive to elevated concentrations of zinc were identified via transposon mutagenesis in the common soil bacterium, Pseudomonas fluorescens ATCC13525. Some of these genes were essential to maintain metal homeostasis in the bacterial cell. DNA sequences of the transposon-tagged genes were determined by DNA sequencing of arbitrary PCR products. DNA sequence analysis indicated that one gene was similar to P-type ATPases responsible for transporting metal ions out of the cell. The corresponding mutant was sensitive to zinc, cadmium, and lead indicating that this gene may be responsible for defending Pseudomonas fluorescens against these metal ions. Four zinc-induced genes shared similarity with pyoverdine synthetase genes. The corresponding mutants were unable to produce the iron-scavenging siderophore pyoverdines. One other mutant was sensitive to zinc, cadmium, and copper. The gene targeted by the transposon in this mutant did not show any homology to known genes in databases. This may indicate the presence of a novel and heretofore unidentified cellular mechanism playing a role in metal tolerance.

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