published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

Batch and column experiments were performed to investigate the adsorption of bacteriophage MS-2 to silica at pH 5. Linear isotherm analysis of batch experiment data gave partition coefficient (KP) estimates of 270 cm³/g and 580 cm³/g for 4°C and 24°C, respectively. Breakthrough-type column experiments indicated that sorption and desorption were slow, as evidenced by a slow approach to breakthrough and tailing of the desorption limb. A non-equilibrium advection-dispersion model with all adsorption sites on the silica assumed to be kinetically controlled was used to model the column data. The model-generated parameters yielded Kp estimates 1000-fold smaller than those given by isotherm analysis and indicated that the time scale for desorption is on the order of 1-6 hours.

Enterococcus species are integral members of the gastrointestinal microfloral of humans, animals, birds, as well as insects. Their presence in water and food has been greatly associated with faecal contamination. This study was aimed at evaluating the incidence of Enterococcus species in cow dung and environmental water sources in three commercial dairy farms. In addition, their antibiotic profiles were determined as well as resistance and virulence genes. Furthermore, the genetic relatedness of the isolates was determined by molecular typing method (RAPD PCR). Three hundred and thirty four water and faecal samples consisting of 117, 116 and 101 were collected from Seven Star Middle Drift and Fort Hare Dairy trusts respectively. Of the 334 samples collected, 289 were of faecal origin and 45 from water sources within the farms. All samples were screened for enterococci using culture base growth media and molecular methods targeting the tuf gene. Speciation was done using species-specific primers and the incidences of various species within the farms determined. Furthermore resistance to antibiotics and multidrug-resistant phenotypes were established using the disk diffusion method. Genes coding for virulence and resistance were also determined. From the samples collected, 313 (289 faecal and 24 water) presumptive enteroccocci were isolated, 305 of 313 (97.45 percent) were confirmed as Enterococcus of which 239 of 305 (78.38 percent) were identified as E. hirae, 15 of 305 (4.92 percent) as E. faecium, 12/305 (3.93 percent) as E. durans, 6 of 305 (1.97 percent) as E. faecalis and 33 of 305 (10.82 percent) were unidentified. Out of the five virulence genes that were targeted in the study only gelE (71.80 percent of 219/305) and ace (27.2 percent 83/305) were present in the isolates. Phenotypic resistance to antibiotics was observed is in all twelve antibiotics tested with multidrug resistance phenotypes detected in some enterococcal isolates most predominant in Seven Star and Middledrift dairy trust. Finally RAPD profiles of the isolates showed high relatedness between the strains from water and cow dung sources in all three commercial dairy farms suggesting possible contamination from cow dung to the water sources or vice versa.

Call number: LD2668 .T4 1949 G71 / Master of Science

Typescript, etc.

Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 89-94).

This thesis studies antibiotic sensitivity of bacteria isolated from city water distribution systems.

Present methods of counting and sizing of bacteria arc usually tedious and often have low statistical validity. The objective of this thesis was to investigate the feasibility of counting and sizing of bacteria with the Coulter Counter and to evaluate orifices which were prepared in this laboratory. Size distributions of Pasteurella multocida and Proteus vulgaris were obtained with the electronic particle counter. These distributions appeared to follow the normal distribution when relative per cent was plotted against diameter, The two modes of the distributions appeared far enough apart to warrant future attempts to separate quantitatively <i>P. vulgaris and P. multocida </i>in mixed suspensions. Size distributions also were obtained for <i>Staphylococcus epidermidis, Sarcina lutea,</i> and <i>Azotobacter</i>. Many variables appeared to be inherent in the electronic particle method of counting biological cells; among these are the biological cells, diluent, and electronic circuitry. Apparently the variability in the electronic circuitry caused the calibration of laboratory orifices to be impossible according to conventional methods. / Master of Science

The purpose of the investigation was to determine if coliform organisms isolated on membrane filters can be incubated at a humidity below the point of saturation. The investigation consisted of comparing the development of coliform organisms on membrane filters incubated at various controlled levels of humidity with the development of coliform organisms incubated in a saturated atmosphere. The effect of humidity on various types of differentiating media was considered simultaneously with the above investigation. Several suggested methods for the regulation of humidity were examined and evaluated and two new methods were developed. The final results indicate that it is possible to incubate coliform organisms on membrane filters at all levels of humidity above 35 percent saturation. There was no significant difference noted in the results obtained on the four differentiating mediums: Two Step Endo, Single Step Endo, Hajna-Damon Endo and Dehydrated Schedule Nutrient. Gooch tubing provides a more nearly watertight seal in the membrane filter procedure than either Parafilm or Plastic Disposable Petri dishes. The relative humidity of a standard incubator may be regulated to any desired level up to about 85 percent by exposing a definite water surface area per unit volume of incubator space. This procedure permits ordinary incubators to be used for membrane filter examinations. / Master of Science

The purpose of the problem was to develop a laboratory technique for mass culturing of the aquatic actinomycetes. In order to solve the problem, it was necessary to devise a suitable culture chamber that would nurture the various species in both primary and secondary stages. It was also important to provide an adequate medium for growth of these organisms. Finally, the construction of the culture chambers must provide for a continuous exhaust of the taste and odor compounds so that the production of these components could be correlated with growth stages.