Theses and Dissertations

Issuing Body

Mississippi State University

Advisor

Aarattuthodi, Suja

Committee Member

Griffin, Matt J.

Committee Member

Khoo, Lester H.

Date of Degree

8-6-2021

Original embargo terms

Complete embargo for 2 years

Document Type

Graduate Thesis - Open Access

Major

Wildlife, Fisheries and Aquaculture

Degree Name

Master of Science

Degree Name

Master of Science (M.S.)

College

College of Forest Resources

College

College of Forest Resources

Department

Department of Wildlife, Fisheries and Aquaculture

Department

Department of Wildlife, Fisheries and Aquaculture

Abstract

The gram-negative bacteria Edwardsiella ictaluri causes significant economic losses in aquacultured fish. Generally considered host-specific to catfish, there are reports of E. ictaluri outbreaks from other aquacultured species, including ornamental fish raised in the southeastern U.S. Thus, a comprehensive phenotypic and genotypic characterization of E. ictaluri isolates from catfish and ornamental aquaculture was warranted. Morphological, biochemical, and protein profiles of catfish and ornamental derived isolates were mostly similar. Plasmid profiles of wild-type isolates were consistent within groups. Analysis of putative anti-microbial resistant isolates from catfish revealed the presence of multi-drug resistant plasmids. Genomic comparisons indicated marked differences among host groups, including unique T4SSs and phage elements among ornamental fish-derived E. ictaluri isolates. An optimal MLSA scheme consisting of eight reference genes was defined, revealing isolates from catfish and ornamental aquaculture form two discrete phyletic lineages. This study advances our understanding of E. ictaluri affecting two important agricultural commodities in the U.S.

Sponsorship

USDA National Institute of Food and Agriculture (NIFA) Southern Regional Aquaculture Centre (SRAC)

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