Browsing by Subject "Bacteriophages"
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Item Antitermination is operative in bacteriophage T7 and is largely dependent on one promoter(2008-08) Robins, William Paul; Molineux, IanThe 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.Item Bacteriophage therapy of Clostridium difficile induced intestinal disease in a hamster model(Texas Tech University, 1998-12) Ramesh, VijayashreeNot avaiableItem A phage cocktail approach for the control of iron bacteria from biofouled water supply wells(2015-05) Ochoa, Gustavo E.; Kirisits, Mary Jo; Kinney, Kerry KBiofouling refers to the accumulation of biofilm and biogenic precipitates on wetted surfaces and is one of the major problems associated with groundwater production. Groundwaters rich in ferrous iron (Fe(II)) are particularly susceptible to biofouling due to the low energetic yield of Fe(II) oxidation, which forces ironoxidizing bacteria to convert large quantities of soluble Fe(II) to insoluble ferric iron (Fe(III)) to sustain growth. Bacteria-specific viruses, known as bacteriophages or phages, are particularly promising for biofilm control given their specificity and ability to spread from one host cell to another. Phage therapy for biofilm control has been most successful with pure cultures and low-diversity bacterial communities. However, the applicability of phages to control mixed bacterial communities, in particular those of groundwater supply wells, remains largely unexplored. To assess whether phages constitute an effective alternative to treat well biofouling, the microbial communities of two biofouled wells were interrogated by 16S rRNA gene sequencing. Potential key species of iron bacteria (FeB) were identified and enriched by repeated subculturing in vii Modified Wolfe and Winogradsky media. Mixed phage suspensions were extracted by filtration from activated sludge, and this suspension was enriched against bacterial enrichment cultures developed from well water inocula. Batch tests showed a decrease in cell density and an impairment in iron redox cycling on well enrichment cultures when exposed to phage suspensions. Future work includes testing the phage suspensions against mixed biofilms of FeB, characterizing the specificity of these phage suspensions, and evaluating the impact of the phage on iron redox cycling under other culture conditions. Overall, this work is a first step toward a sustainable rehabilitation approach for biofouled wells.Item Phage display technology for surface functionalization of a synthetic biomaterial(2005) Sanghvi, Archit Bharat; Schmidt, Christine E.Item Screening pesticides with a colorimetric phage induction essay(Texas Tech University, 1981-05) Hume, Sharlene HelenNot availableItem Temperature dependent release of BB' subunits of DNA-dependent RNA polymerase from folded nucleoids of Escherichia coli dnaA [superscript] ts mutants and location of the 1c gene of bacteriophage PA-2(Texas Tech University, 1980-05) Eaton, Leslie C.Not availableItem The protection of recombinationless Bacillus subtilis from four-nitroquinoline-one-oxide treatment by infection with bacteriophage PBS-1(Texas Tech University, 1970-12) Strong, James EvansNot availableItem The VC-4: A Virus Concentration System For Field Use(Texas Tech University, 1981-08) Von Phul, Stephen AllenNot Available.