Theses and Dissertations

Issuing Body

Mississippi State University


Suja Aarattuthodi

Committee Member

Matt J. Griffin

Committee Member

Lester H. Khoo

Date of Degree


Original embargo terms

Complete embargo for 2 years

Document Type

Graduate Thesis - Open Access


Wildlife, Fisheries and Aquaculture

Degree Name

Master of Science


College of Forest Resources


Department of Wildlife, Fisheries and Aquaculture


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.


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

Available for download on Tuesday, August 15, 2023