Temporal dynamics of vibrio populations in the subtropical estuary and coastal waters

Abstract

Bacteria are an important component of the marine ecosystem responsible for production, nutrient cycling, and decomposition. Since bacteria are abundant and diverse globally, their interactions with the dynamic environment have been the research focus that provides insights into how climate change impacts the marine ecosystem. In this study, we studied the effects of environmental factors on the temporal dynamics of the coastal bacterial community by 16S rRNA and hsp60 gene sequence analysis. By isolating coastal bacterial communities from Deep Bay and Clear Water Bay, we revealed significant differences in the compositions due to environmental variability. Canonical correspondence analysis suggested that salinity was the primary factor in shaping the distinct communities between estuarine and coastal environments, and temperature played a role in determining the seasonal succession of bacteria. To investigate the change in bacterial composition with respect to environmental variations, we focused on Vibrio as a model organism. The genus has been extensively studied due to its ubiquity, genetic and metabolic diversity, and pathogenic potential from V. cholerae, V. parahaemolyticus, and V. vulnificus. By analyzing hsp60 gene sequences, we observed that the Vibrio community in Deep Bay has a higher total abundance and a more diverse community composition. Different seasonal patterns were also observed between the two locations. By culturing methods, we revealed that the Vibrio strains distributed on the phylogeny based on their habitat and water temperature at isolation and formed three putative clades. Laboratory-based growth experiments also supported thermal adaptations in these phylogenetically related strains by shifts in thermal range, optimal growth temperature and maximum growth rate. These findings provide insights into the studies on virulence emergence in environmental Vibrio strains, especially under the influences of ocean warming, and contribute to the ecological monitoring and risk assessment of Vibrio infections.

Date of Award	2023
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology
Supervisor	Charmaine YUNG (Supervisor)