Population dynamics of Vibrio cholerae and its bacteriophage Open Access
Wei, Yan (2010)
Published
Abstract
Population dynamics of Vibrio cholerae and its
bacteriophage
by
Yan Wei
Cholera is a diarrheal disease caused by toxigenic strains of
Vibrio cholerae. Individuals
contract cholera by consuming water or food contaminated with
virulent V. cholerae
from the aquatic reservoir. Field studies and epidemiological
observations suggest
bacteriophage that specifically infect V. cholerae may limit
the severity of cholera
outbreaks by killing bacteria present in the reservoir and in
infected individuals. My
dissertation is intended to enhance our understanding of how
vibriophage modulate
cholera outbreaks by combining laboratory experiments and
mathematical modeling. My
research shows that when V. cholerae was cultured with
single species of phage, bacterial
populations were only temporally limited by phage due to the rapid
evolution of phage-
resistant bacteria (chapter2). After phage-resistant bacteria
emerged and dominated the
community, bacterial populations were limited by resource rather
than phage. However,
these bacterial mutants exhibited an extreme fitness disadvantage
relative to the wild-
type, suggesting that resistant bacteria may not play an important
role in the ecology and
epidemiology of cholera. In chapter 3, I present results for
conditions under which V.
cholerae population was controlled by co-culturing with two
different phage species over
extended time (~ 650 hours). One of the two phage species displayed
features that were
not observed in well-studied lytic and lysogenic phage.
Mathematical simulation of the
population dynamics of this particular phage and its bacterial
hosts suggests that this
phage might induce a persister-like of bacterial sub-population
as some antibiotics do.
Taken together, the above-described results support the hypothesis
that phage predation
plays an important role in the waning of cholera outbreaks. Chapter
4 discusses the topic
"evolution of bacterial motility", which, while not directly
related to bacteria-phage
dynamics, was inspired by some of the findings from chapter 2. I
hypothesize that
motility is evolutionarily favored because it enables bacteria to
move apart from each
other, thereby allowing individual bacteria to obtain greater
shares of limiting resources.
Using a mathematical model and experiments with motile and
non-motile strains of E.
coli and V. cholerae, I test this hypothesis and
explore the conditions under which
motility provides bacteria with a fitness advantage in initially
homogenous nutrient-
limited spatially structured habitats.
Table of Contents
Contents
1. Chapter 1. INTRODUCTION
1.1 Cholera : background and history / 1
1.2 Factors affecting cholera outbreaks / 3
1.3 Bacteriophage : history and the role in cholera epidemics / 6
1.4 Population dynamics of bacteria and bacteriophage : in the laboratory and in the environment & mechanisms of bacterial resistance to phage / 13
1.5 Summaries of Chapter 2,3&4 / 19
2.
Chapter 2. AN
EXPERIMENTAL STUDY OF THE POPUATION AND EVOLUTIONARY DYNAMICS OF
VIBIRO CHOLERAE O1 AND THE BACTERIOPHAGE
JSF4
2.1 Introduction / 23
2.2 Materials and Methods / 25
2.3 Results / 31
2.4 Discussion / 41
3. Chapter 3. THE POPULATION and EVOLUTIONARY DYNAMICS of VIBRIO CHOLERAE and ITS BACTERIOPHAGE: CONDITIONS FOR MAINTAINING PHAGE-LIMITED COMMUNITIES
3.1 Introduction / 47
3.2 Materials and Methods / 50
3.3 Results / 54
3.4 Discussion / 68
4. CHAPTER 4. THE POPULATION and EVOLUTIONARY DYNAMICS of BACTERIA IN PHYSICALLY STRUCTURED HABITATS: THE ADAPTIVE VIRTUES OF MOTILITY
4.1 Introduction / 72
4.2 Results / 76
4.3 Discussion / 83
4.4 Methods / 87
5. CHAPTER 5. SUMMARY AND DISCUSSION
Summary and Discussion / 91
6. BIBLIOGRAPHY
Bibliography / 97
7. APPENDIX
7.1 Supplementary Information to chapter 2 / 109
7.2 Supplementary Information to chapter 3 / 119
7.3 Supplementary Information to chapter 4 / 131
About this Dissertation
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Primary PDF
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Population dynamics of Vibrio cholerae and its bacteriophage () | 2018-08-28 13:33:11 -0400 |
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Supplemental Files
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Appendix.doc () | 2018-08-28 13:38:29 -0400 |
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