Date of Award

Fall 2023

Document Type

Open Access Dissertation

Department

Environmental Health Sciences

First Advisor

Robert Norman

Abstract

Climate change-induced stressors, such as temperature, salinity, pH, and wildfire, are contributing factors to the increase in frequency of Vibrio infections, altering Vibrio geographical constraints. At the same time, the expansion of the coastal population is resulting in increased input of treated municipal wastewater into areas that are also experiencing Vibrio proliferation. Given that increases in ocean temperature and sea level coupled with increases in human activity in coastal waters support greater Vibrio-human interactions, it is important to examine factors and mechanisms within this socio-ecological coupled system that may further strengthen this interaction. This study aimed to better understand the influence of environmental factors, especially temperature and pH, and the effect of treated wastewater effluent and wildfire ashes as anthropogenic factors on Non-cholera Vibrio spp. growth and gene expression. To examine the effect of temperature and pH on bacterial growth, V. vulnificus and V. parahaemolyticus were grown at 25ºC, 30ºC, and 37ºC in pHs ranging from 5 to 9.6. Integrated transcriptomic approaches were used to analyze changes in overall gene expression of V. vulnificus exposed to wastewater treatment plant effluent and wildfire ashes. Multiple optimal growth conditions in terms of temperature and pH were found for Vibrio growth depending on the mode of growth and their interaction with different stressors, suggesting that Vibrio may express adaptive responses, switching between planktonic to biofilm modes of growth to resist changes in their local environment, potentially increasing bacterial survival under climate change scenarios and increasing Vibrio-human interactions. Wastewater exposure increased V. vulnificus growth and upregulated genes and pathways involved in bacterial survival during the early stages of infection in a host. The exposure to wildfire ash altered V. vulnificus growth and gene expression depending on the trace metal composition of the ash. The vegetation ash enhanced bacterial growth while the structural ash suppressed growth. The overall pattern of upregulated genes and pathways suggests increased virulence potential due to the co-selection of metal and antibiotic resistance. These combined socio-ecological interactions may lead to the selection of environmental reservoirs of Vibrio strains with enhanced virulence profiles, increasing public health risk.

Rights

© 2024, Karlen Enid Correa Vélez

Download

Share

COinS