Environmental Effects on Lambda Lysogeny and Spiteful Attack Público

Abstract

Lysogeny is one of two life paths that a lambda phage may take when entering a susceptible cell. The probability of lysogeny varies with environmental factors; such as the density of susceptibles, chemical factors, and number of phage present. Additionally, lysogeny appears to have many benefits for the cell and the phage. One potential benefit of lysogeny is the capability of a lysogen to use spiteful attack, where the lysogen induces so that the phage can kill off any competitors and allows the lysogen population to have control over a resource rich area. The current study examined the effects of environmental factors on lambda lysogeny and spiteful attack in Escherichia coli. Specifically, the effect of nutrition and changing the initial population ratios between lysogenic and sensitive bacteria. First, parameters for the bacteria and the bacteriophages were determined in each of the environmental conditions. Then, competition assays were run between one lysogenic strain and one sensitive strain for three generations.  For 1:1 assay using the MG1655-lkan, the lysogenic bacteria outcompeted the sensitive bacteria in the LB and S-medium + 0.1% NH4Cl + 0.1% Glucose. Future studies should look at the impact varying the ratio of sensitive bacteria to the MG1655-lkan and a slower growing lysogen than the MG1655-lkan, and the impact of spatial structure on competition.

Table of Contents

Table of Contents

Introduction ……………………………………………………………………………………… 1

Material and Methods …………………………………………………………………………… 4

           Bacterial Strains and Media……………………………………………………………... 4

           Growth Parameters …………………………………………………………………….….6

           MIC Determination ………...…………………………………………………………..…7

Selective Plating………...………………………….…………..……………….…………8

Phage Plating………..............………………………………………………….…………8

Bacteriophage Parameter Estimates……………………………………………………….9

       Competition Assays……………………………………………………………………...11

Results ………………………………………………………………………………………… 12

           Bacteria Parameters …………………………………………………..………………... 12

           Bacteriophage Parameters …………...……………………………………………….... 14

           Competition Assays ………………….…………………………………………………15

Discussion ...…………………………………………………………………………………… 16

Table of Contents: Tables and Figures

Materials and Methods

     Table 1…………………………………………………………………………………….5

Table 2…………………………………………………………………………………….6

Table 3……………………………..……………………………………………..……….7

Table 4…………………………………………………………………………………….8

Results

Figure 1………………………………………………………………………..…………12

Table 5………………………………………………………………………...…………13

Figure 2………………………………………………………..…………………………14

Figure 3………………………………………………..…………………………………15

Figure 4………………………..…………………………………………………………16

About this Honors Thesis

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School	Emory College
Department	Biology
Degree	B.S.
Submission	Honors Thesis
Language	English
Research Field	Biology, Microbiology Biology, Virology Biology, Ecology
Palavra-chave	E. coli Bacteriophage Escherichia coli Lysogeny Bacteria Lambda Spiteful Attack
Committee Chair / Thesis Advisor	Dr. Nicole Vega, Emory University
Committee Members	Dr. Minsu Kim, Emory University Dr. Kathleen Campbell, Emory University

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