Date of Award

Spring 2018

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Coastal Sciences, Gulf Coast Research Laboratory

Committee Chair

Dr. Darrell Jay Grimes

Committee Chair Department

Coastal Sciences, Gulf Coast Research Laboratory

Committee Member 2

Dr. Wei Wu

Committee Member 2 Department

Coastal Sciences, Gulf Coast Research Laboratory

Committee Member 3

Dr. Robert J. Griffitt

Committee Member 3 Department

Coastal Sciences, Gulf Coast Research Laboratory

Abstract

Free-ranging marine elasmobranch tissue-associated micro-organisms were cultured from free-ranging Atlantic stingray (Dasyatis sabina) and Atlantic sharpnose sharks (Rhizoprionodon terraenovae). 16S rRNA gene phylogeny indicated bacteria community structure in both elasmobranchs were under phylum Proteobacteria, Firmicutes and Actinobacteria. By conducting split-plot ANOVA, we found the microbial richness is significantly different (P=0.0814) between two superorders of elasmobranch, which may largely due to their preferred habitats and feeding habits. Urease presentence and activity was detected in phylogenetically diverse bacterial strains. Species with high urea-hydrolyzing ability, such as Micrococcus luteus (shark blood isolate: 46.84 mU/mg protein; stingray blood isolate: 24.36 mU/mg protein) and Staphylococcus saprophyticus (could also be xylosus) (66.46 mU/mg protein) were both isolated from blood samples. This study suggests the examination of urease activity to promote the better profile of the virulence of some novel bacteria species. The phylogeny of bacterial 16S rRNA genes and urease-coding ureC genes were analyzed and compared,combined with the examination of urease activity of ureolytic bacteria, we found ureC gene as a potential functional marker. The study of enzymatic (urease) activity and ureC gene-based phylogeny provides a better understanding of ureolytic bacteria for their urea-utilizing potential, enables the further study of urease-positive strains on bioengineering and bioremediating of marine urea eutrophication in a larger scale.

To our knowledge, this should be the first study to unveil the urea-hydrolyzing ability of marine elasmobranch tissue-associated ureolytic microbes, and the potential of the ureC gene to be a functional marker.

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