Bela B. Toth

Abstract

In induction experiments with naturally occurring and artificially lysogenic strains of S. potsdam, cells were irradiated in buffer, transferred to complete medium, and then assayed for free phage. Irradiation was followed by half hourly samples for free phage from the growing populations of irradiated cells. For an estimation of burst sizes, the irradiated cells were diluted out to a final concentration of 1 cell per ml and distributed to tubes in 0.5 ml quantities. All assays were done by the top-layer method with streptomycin incorporated in the top-layer and SP2-strr as the bacterial indicator. The non-lysogenic strain S. potsdam, SP2, was lysogenized with phages P3 and P4, and a lysogenized strain SP2-9a, c was developed.

Salmonella potsdam, SP9, lysogenic with two phages, P9a, B type, and P9c, A type, which showed differences in UV inactivation properties for the isolates selected (SP9(8), SP9(9), and SP9(10), proved to be similar in induction properties. However, the percent induction of cells induced to release P9c was influenced by the concentration of cells irradiated whereas the percent induction of cells irradiated to release P9a was not influenced by the cell concentration. This result was attributed to a shielding of cells by other cells at high concentrations. Artificially lysogenic cells for phage P9a (SP2-9a, c and SP2-9c, a) had a much greater reduced percent induction than phage P9a from SP9. Thus, a host modifying factor is evident. It was considered possible that this result could be caused by difference in prophage, chromosomal location.

The burst sizes of phages P3 and P4 when introduced into SP2 were considerably greater than the burst size from SP3 and SP4 respectively. Thus there was a modification of the induction properties of P3 and P4 in the new host. Another observation was the longer latent period for P4 of SP4 than for SP2-4. The burst size of P4 in both SP2-3, 4 and SP2-4, 3 was reduced compared to the burst size of SP2-4. This reduction could not be attributed to the induction and growth of both P3 and P4 inside the same cell, since the probability of induction of both phages together was low. Thus it appeared that the presence of prophage P3 has modified the burst size of P4 in SP2 lysogenized with both phages.

LLU Discipline

Microbiology

Department

Microbiology

School

Graduate School

First Advisor

Leonard R. Bullas

Second Advisor

Richard E. Beltz

Third Advisor

Robert L. Nutter

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

1966

Date (Title Page)

9-1966

Language

English

Library of Congress/MESH Subject Headings

Salmonella

Type

Thesis

Page Count

viii; 67

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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