Doctoral Dissertations

Date of Award

12-2023

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Environmental and Soil Sciences

Major Professor

Jie(Joe) Zhuang

Committee Members

Jie(Joe) Zhuang, Mark Radosevich, Yuji Arai, Jennifer DeBruyn, Qiang He

Abstract

Soil viruses are ubiquitous and greatly impact the structure and function of soil microbial communities, with their effects modulated by various environmental factors. This study investigates the inactivation of naturally occurring soil viruses in sterilized soil, as well as the effects of cadmium (Cd) exposure and carbon (C) and nitrogen (N) nutrient availability on the population dynamics of virus-host communities in agricultural soil.

Lab-scale slurry and unsaturated experiments were performed to examine virus inactivation in the absence of host bacteria in sterilized soil. In slurry experiments, virus abundance declined by over 90% after 10 days of incubation. The addition of bacteria mitigated this decrease, though a declining trend persisted. In unsaturated experiments, virus abundance initially decreased from 1E+09 to 4.49E+08 after 10 days, followed by a substantial increase to 6.76E+09 on day 13 upon bacteria reintroduction. Further experiments assessed the impact of Cd exposure and nutrient availability on soil virus dynamics, demonstrating that both Cd and incubation time significantly influenced virus diversity and abundance, with Cd inducing prophage activation.

This research highlights the complex relationships within soil microbial communities and their implications for agricultural ecosystems, focusing on the survival of fresh soil viruses in the absence of host bacteria and the impact of heavy metal exposure on virus dynamics. Integrating viral activity into the overall function of soil food webs can improve our understanding of soil health, optimize soil management practices, and potentially lead to novel virus-based applications in crop health.

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