Detection and partitioning of bacteriophage in fluid/solid systems: application to the ecology and mobility of viruses in the environment

[摘要] Viruses are ubiquitous in natural environments where they can exist as natural inhabitants or as contaminants from the disposal of human and animal wastes. Studies of viruses in nature are hampered because currently available methods for detection are not ideally suited to environmental applications. In the first part of this thesis, a modified hybridization assay is presented which employs DNase protection and slot blot methods to measure quantitatively the concentration of soluble and bacteriophage-encapsulated DNA in fluid samples. The potential use of this assay for estimating virus viability was tested with a model system consisting of inactivating bacteriophage lambda particles. These experiments show that the new hybridization assay provides upper-limit estimates of bacteriophage viability when inactivation results in the release of DNA.The mobility and ecology of viruses in natural environments is strongly influenced by the adsorption of virus particles to solid surfaces. In the second part of this thesis, a kinetic theory for virus adsorption and inactivation in batch experiments is presented. Based on the results of this theory, a new experimental approach is proposed for studying the effects of solid surfaces on virus partitioning and survival over long time scales.In the third part of the thesis, this new experimental approach was used to investigate the interactions between bacteriophage lambda particles and Ottawa sand over the course of days. Virus/surface interactions on these time scales were strongly dependent on solution pH and electrolyte composition. Sand stabilized the virus at high pH (10) and reduced fluid-phase virus infectivity at intermediate to low pH (5 and 7). The observed reduction in virus infectivity at pH 7 was attributed to virus adsorption to the sand surface, based on data from elution experiments. Viruses adsorbed to the sand at pH 7 desorbed when the sand was resuspended in nutrient broth, but not when the sand was resuspended in a virus-free pH 7 buffer. When model simulations were compared to elution data, virus adsorption did not follow the predictions of quasi-equilibrium adsorption models. On the basis of these results, several alternative kinetic mechanisms for virus adsorption are proposed.

[发布机构] University:California Institute of Technology;Department:Engineering and Applied Science

[关键词] Environmental Science and Engineering