The translocation of the T7 genome into the cell is a multistep process. Following adsorption, approximately 850bp of the 40kb linear genome is internalized to expose host-specific promoters in the leading end to transcription components. There are three strong early promoters, PA1, PA2, and PA3 on this leading 850 bp. Further T7 genome internalization is coupled to transcription and I have measured internalization rates to characterize the rate of transcription by E. coli RNA polymerase in vivo. E.coli RNAP internalizes the entire 40kb and distal parts of the genome are internalized nearly as efficiently and at the same rate as the leading end. I have shown that processivity is dependent on the antitermination element boxA, located 63 bp downstream from PA3, and on only one of the three early promoters. However, when any one of boxA, PA3, or the host antitermination factor nusB is mutated the efficiency, rate, and apparent processivity of transcription -- and thus the efficiency of genome internalization are all significantly reduced. The PA3 promoter, boxA, and E. coli nusB are all non-essential for T7 growth, but they confer a fitness benefit to wild-type phage by increasing the rate of genome internalization. In T7, the minimal requirement for antitermination is promoter PA3 and the boxA sequence. I have found that transcripts initiating at PA1 and PA2 are not effectively antiterminated by boxA, however those from PA3 alone do. Upon further investigation it was shown that there is a requirement for sequences upstream of the -35 hexamer of PA3 to confer full antitermination. After T7 expresses its own single-subunit RNA polymerase, bacteriophage T7 must shutoff host transcription via the phage proteins gp0.7 and gp2. In the absence of host RNAP shutoff, T7 DNA is degraded and the infection fails. I have found that the absence of either promoter PA3 or boxA,gene 2 is unnecessary for growth. These results argue the target for shutoff is actually antiterminating transcription. / text

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Includes bibliographical references / 183, [111] leaves, [6] leaves of plates : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Biochemistry, 1990

Bibliography: p. 90-96 / v, 96 p. [70] leaves [26] leaves of plates : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Biochemistry, 1984

Bacteriophage (phage), virus of bacteria, has been proposed as a mean to inactivate bacteria that are pathogens of humans. Applied prophylatically to food, phage might decrease the numbers of potential pathogens we ingest. Much active research on using the phages of bacteria to control Gram negative foodborne pathogens are described in the literatures, but comparatively little research describes the phages of Gram positive bacteria and their use as biocontrol agents on food. In this work, previous undescribed phages, able to infect Bacillus cereus and Listeria monocytogenes, were isolated from soil and ruminants faecal material, respectively. As the first step in assessing their potential as biocontrol agents, the isolated phages were purified, concentrated and characterised (albeit to different degrees). The Bacillus phages had a narrow host range while the Listeria phages had a broad host range. Listeria phages also infected L. monocytogenes 2000/47, a strain which recurs in New Zealand clinical cases. Both Bacillus and Listeria phages appeared to be of the Myoviridae family judging by their structure in electron micrographs. The Bacillus FWLBc1 and FWLBc2 phages were lytic phages with a latent period of 106 and 102 min at 37°C, and an average burst size of 322 and 300 phages per infected cell, respectively. Moreover, they both had genomes of approximately 134 kb. All newly isolated and characterized phages were chloroform resistant and survived storage better at 4°C than at room or freezing temperatures. Bacillus phages significantly reduced the bacterial population in mashed potatoes within 24 h at room temperature, when applied at a phage to host ratio of 1000. Listeria phages rapidly inactivated the host population to a low optical density. The findings of this thesis will add to the current knowledge of phages in the context of various environmental conditions for different bacteria and will demonstrate the potential of phages as food safety biocontrol agents.

Thesis (Ph. D.)--University of Adelaide, Dept. of Biochemistry, 1986. / Includes bibliographical references.

Thesis (Ph.D. 1979) from the Department of Biochemistry, University of Adelaide.

Thesis (Ph.D.)--University of Adelaide, Dept. of Microbiology and Immunology, 1998? / Includes bibliography (27 leaves).

Thesis (M.S.)--University of Delaware, 2008. / Principal faculty advisors: Yan Jin, Dept. of Plant & Soil Sciences; and Pei C. Chiu, Dept. of Civil & Environmental Engineering. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1957. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 94-100).