| The accurate recovery and detection of microbes from water samples is important for the protection of public health. However, not all microbes behave similarly, not all water samples have comparable physical properties, and the constituents present in samples can affect microbe properties and recoverability. This dissertation consists of four separate projects that are linked by the common theme of detection efficiency improvement for microbes in water samples.;In the first project, various modifications to USEPA Method 1623, for the detection of Cryptosporidium and Giardia, were examined. Each successful modification was incorporated into the method, and use of the final, modified method resulted in a 20% increase in Cryptosporidium recovery from reagent water and a 41% increase in Cryptosporidium from surface water samples. Additionally, the recovery of Giardia was improved by 37% in reagent water and 17% in surface water samples.;Similarly, the second research project aimed to improve recoveries of Cryptosporidium and Giardia from water samples. However, this study compared the effectiveness of pleated capsule filters to hollow-fiber ultrafilters for organism recovery in tap water and surface water samples. In tap water, ultrafiltration produced significantly better recoveries of Cryptosporidium (68%) but not Giardia (63%). When surface water samples were analyzed, Cryptosporidium recovery rates were similar for both filter types, while Giardia was recovered significantly better by ultrafiltration (81%).;The third project involved the evaluation of alternative DNA extraction processes and real-time polymerase chain reaction (qPCR) for the detection of Cryptosporidium. After the development of the DNA extraction procedure, tap water samples were seeded and processed, then split prior to detection method. Microscopic detection had a mean recovery of 41%, while samples with qPCR detection had a mean recovery of 49%.;The fourth project focused upon the impact and effects of chemical dispersants. Chemical dispersants have been used successfully in some microbial methods, but there is limited fundamental knowledge of the dispersant effects. Both settling tests and zeta potential analyses were conducted with sodium polyphosphate and sodium metasilicate for multiple particles and microbes in varied water conditions. While settling tests were less effective in the provision of significant results, the zeta potential analyses highlighted some important considerations of for chemical dispersant selection and use. In particular, two inorganic particles and two strains of E. coli were tested, and the stability of the different particles in suspension was impacted differently by the chemical dispersants. |
