Abstract

Plasmid transformation is an essential step in many gene cloning experiments. In Salmonella tynhimurium, mutants of rough strain have shown improved transformation frequency previously. In this work a stable restriction-minus (r-) and modification-plus (m+) strain and its derivatives were constructed. Effect of restriction barrier on transformation of plasmid pBR322 was tested. Several factors which may affect transformation frequency have been systematically examined to determine the optimum conditions for transformation in S. tvphimurium. Efforts were made to simplify the procedure.

Using pBR322 plasmid as an experimental model, the r- strain demonstrated 105 to 106 times better transformation frequency than r+ wild type. A galE and r- mutant further improved the frequency 3 to 7 fold. Among those cations tested, calcium ion is most effective in facilitating transformation. Growth stage of bacteria is critical for optimum competence in transformation. The presence of magnesium in the growth medium or in the washing step is not stimulative but inhibitory to transformation. Heat shock at either 37°C or 42°C shows the similar effect on transformation. A simplified method is presented which facilitates plasmid transfer and genetics study in S. typhimurium.

LLU Discipline

Microbiology

Department

Microbiology

School

Graduate School

First Advisor

Jun-ichi Ryu

Second Advisor

Anthony J. Zuccarelli

Third Advisor

George T. Javor

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

1988

Date (Title Page)

9-1988

Language

English

Library of Congress/MESH Subject Headings

Salmonella typhimurium; Transfection

Type

Thesis

Page Count

vi; 118

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

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