The major outer membrane protein OprF from Pseudomonas aeruginosa was compared with OprF from the fluorescent phytopathogen Pseudomonas syringae. The P. syringae oprF gene was subcloned and sequenced and found to code for a sequence of 344 amino acids containing a 24 amino acid leader sequence. The mature protein, with a deduced molecular weight of 34,225, contained four cysteine residues and an alanine-proline rich area. Comparison of the P. syringae OprF amino acid sequence with the P. aeruginosa OprF and the E. coli OmpA sequences showed that the sequences were most similar at the carboxy-terrninal ends. Restriction enzyme site heterogeneity near the oprF gene from nine different P. syringae pathovars was determined. All pathovars had a conserved SalI site within the gene and conserved PstI. and BamHI sites near the ends of the gene. The location of the PstI and the SalI sites outside the gene was variable, although similar. Immunological relatedness between P. syringae OprF from the different pathovars and P. aeruginosa OprF was confirmed. Protein OprF from all the pathovars was shown to be 2-mercaptoethanol modifiable and more easily heat modifiable than was OprF from P. aeruginosa. / Science, Faculty of / Microbiology and Immunology, Department of / Graduate

The human opportunistic pathogen, Pseudomonas aeruginosa PAO1, has been shown to kill the nematode Caenorhabditis elegans. C. elegans has been a valuable model for the study of bacterial pathogenesis, and has reinforced the notion that common virulence and host defense mechanisms exist. Recently, the pyrimidine pathway was shown to regulate virulence levels. Therefore, mutations in the pyrimidine pathway of PAO1 showed decrease virulence in the nematode. When starving the nematode, bacterial resistance was also shown to increase. It was hypothesized that starvation induced the DAF pathway, which regulates the transcription of genes involved with the antibacterial defense mechanism. Further research will be conducted to test this theory by performing RNAi experiments for the genes functioning in the antibacterial defense mechanism.

Cell-free extracts from Pseudomonas fluorescens NCIMB 11764 catalyzed the degradation of cyanide into products that included C02, formic acid, formamide and ammonia. Cyanide-degrading activity was localized to cytosolic cell fractions and was observed at substrate concentrations as high as 100 mM. Two cyanide degrading activities were identified by: (i) the determination of reaction products stoichiometries, (ii) requirements for NADH and oxygen, and (iii) kinetic analysis. The first activity produced CO2 and NH3 as reaction products, was dependent on oxygen and NADH for activity, and displayed an apparent Km for cyanide of 1.2 mM. The second activity generated formic acid (and NH3) pfus formamide as reaction products, was oxygen independent, and had an apparent Km of 12 mM for cyanide. The first enzymatic activity was identified as cyanide oxygenase whereas the second activity consists of two enzymes, a cyanide nitrilase (dihydratase) and putative cyanide hydratase. In addition to these enzymes, cyanide-grown cells were also induced for formate dehydrogenase (FDH), providing a means of recycling NADH utilized by cyanide oxygenase.

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Call number: LD2668 .T4 1956 K55 / Master of Science

Four strains of the fluorescent pseudomonads were studied to determine the effect of controlled atmospheres on the growth and fluorescent siderophore production at pH 6.0 and 7.8. Bacterial strains were grown in Liquid King's Medium B for 48 hr in the presence of O2/CO2 combination percentages of 21.0/0.03, 18.3/3.0, 15.0/6.0, 12.0/9.0, and 9.0/12.0. The bacterial biomass was determined after centrifugation and the siderophores were isolated, partially purified, and quantified spectrophotometrically. Results showed a steady decline in growth and in siderophore production per unit biomass with decreases in the O2/CO2 ratio at pH 7.8 and to a lesser extent at pH 6.0. The average percentage changes in siderophore production levels, relative to control were +0.8, -1.2, -18.2, and -40.6 at pH 6.0; -33.0, -50.4, -66.8, and -64.1 at pH 7.8 in the presence of O2CO2 levels of 18.0/3.0, 15.0/6.0, 12.0/9.0, and 9.0/12.0, respectively.

published_or_final_version / Pathology / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Ecology and Biodiversity / Master / Master of Philosophy

published_or_final_version / Microbiology / Master / Master of Medical Sciences

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