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Microbial Community Composition and Competitive Dynamics Within Squid Symbioses.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Microbial Community Composition and Competitive Dynamics Within Squid Symbioses./
Author:	Smith, Stephanie.
Description:	1 online resource (131 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 84-11, Section: B.
Contained By:	Dissertations Abstracts International84-11B.
Subject:	Microbiology. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30419897click for full text (PQDT)
ISBN:	9798379552954

Microbial Community Composition and Competitive Dynamics Within Squid Symbioses.
Smith, Stephanie.

Microbial Community Composition and Competitive Dynamics Within Squid Symbioses. - 1 online resource (131 pages)

Source: Dissertations Abstracts International, Volume: 84-11, Section: B.

Thesis (Ph.D.)--The University of North Carolina at Chapel Hill, 2023.

Includes bibliographical references

Animals evolved surrounded by bacteria, resulting in widespread symbioses in which host and symbiont often form specialized partnerships that are essential for host development, reproduction, or survival. During host-colonization, bacteria are often forced together within a physical space, providing opportunities for competitive and cooperative interactions that ultimately shape the microbial community within a given host. The first three chapters of this dissertation use the light organ symbiont Vibrio fischeri as a model bacterium for studying these complex microbial interactions. V. fischeri encodes a strain-specific T6SS, a contact-mediated killing mechanism found broadly distributed among host-associated bacteria. I designed a microscopy workflow to quantify contact-dependent competition at the single-cell level and applied this technique to study competitive interactions between lethal and non-lethal V. fischeri strains in vitro. Then, I used this assay in combination with a subcellular biomechanical model for T6SS to investigate killing dynamics within lethal-lethal interactions. This study revealed that strains with the ability to activate T6SS more quickly under host-like conditions outcompete slower-activating strains, even if both isolates are lethal. In addition to T6SS, V. fischeri encodes both conserved and strain-specific mechanisms for horizontal gene transfer (HGT). Using an experimental evolution assay designed to detect transfer of selectable chromosomal markers, I found that V. fischeri exchanges chromosomal DNA in coculture in a manner inconsistent with any HGT mechanism that has been previously described in V. fischeri. Although squid light organs represent an important model for bacterial interactions, we currently lack a fundamental understanding of the natural microbial community across other squid body sites. In the final chapter of this dissertation, I characterized the microbial community of mantle, gill, sub-mantle tissue, and accessory nidamental glands of wild-caught Lolliguncula brevis squid using a combination of culture-based techniques, microscopy, and amplicon sequencing. I found that L. brevis hosts multiple species of culturable Vibrios, a core community of Bradyrhizobium that is conserved across body sites, and a surprisingly diverse gill community. Taken together, this dissertation provided new tools for evaluating interactions between symbiotic bacteria, and also introduced L. brevis as an exciting system that warrants further study into the complexity of squid microbiomes.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2023

Mode of access: World Wide Web

ISBN: 9798379552954Subjects--Topical Terms:

536250
Microbiology.
Subjects--Index Terms:

Bacterial competitionIndex Terms--Genre/Form:

542853
Electronic books.

Microbial Community Composition and Competitive Dynamics Within Squid Symbioses.
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520 $a Animals evolved surrounded by bacteria, resulting in widespread symbioses in which host and symbiont often form specialized partnerships that are essential for host development, reproduction, or survival. During host-colonization, bacteria are often forced together within a physical space, providing opportunities for competitive and cooperative interactions that ultimately shape the microbial community within a given host. The first three chapters of this dissertation use the light organ symbiont Vibrio fischeri as a model bacterium for studying these complex microbial interactions. V. fischeri encodes a strain-specific T6SS, a contact-mediated killing mechanism found broadly distributed among host-associated bacteria. I designed a microscopy workflow to quantify contact-dependent competition at the single-cell level and applied this technique to study competitive interactions between lethal and non-lethal V. fischeri strains in vitro. Then, I used this assay in combination with a subcellular biomechanical model for T6SS to investigate killing dynamics within lethal-lethal interactions. This study revealed that strains with the ability to activate T6SS more quickly under host-like conditions outcompete slower-activating strains, even if both isolates are lethal. In addition to T6SS, V. fischeri encodes both conserved and strain-specific mechanisms for horizontal gene transfer (HGT). Using an experimental evolution assay designed to detect transfer of selectable chromosomal markers, I found that V. fischeri exchanges chromosomal DNA in coculture in a manner inconsistent with any HGT mechanism that has been previously described in V. fischeri. Although squid light organs represent an important model for bacterial interactions, we currently lack a fundamental understanding of the natural microbial community across other squid body sites. In the final chapter of this dissertation, I characterized the microbial community of mantle, gill, sub-mantle tissue, and accessory nidamental glands of wild-caught Lolliguncula brevis squid using a combination of culture-based techniques, microscopy, and amplicon sequencing. I found that L. brevis hosts multiple species of culturable Vibrios, a core community of Bradyrhizobium that is conserved across body sites, and a surprisingly diverse gill community. Taken together, this dissertation provided new tools for evaluating interactions between symbiotic bacteria, and also introduced L. brevis as an exciting system that warrants further study into the complexity of squid microbiomes.
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653 $a Microbiome
653 $a Microscopy
653 $a Symbiosis
653 $a Type VI secretion system
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