All ETDs from UAB

Advisory Committee Chair

Asim K Bej

Advisory Committee Members

Casey D Morrow

Stephen A Watts

Document Type

Thesis

Date of Award

2015

Degree Name by School

Master of Science (MS) College of Arts and Sciences

Abstract

Bacteria residing in the gastrointestinal tract play important roles in digestive physiology and host health. The advent of NextGen sequencing and bioinformatics has made it possible to establish taxonomic profiles with highest coverage, and map these microbes in the gut ecosystem. Although extensively studied in the context of human health, understanding the microbial profiles associated with other organisms will elucidate the roles of the microbial inhabitants to their respective hosts and environment. The microbes of the sea urchin gut have been linked to digestion, processing, and extraction of nutrients from ingesta while within the gut, and have also been implicated in driving molecular transitions of undigested feed components post egestion. Additionally, the sea urchin may be aquacultured in the laboratory for use as model organisms, and understanding the membership and structure of the microbial profiles associated with the digestive tract is imperative for the comprehensive understanding of the health of the organism. To establish the microbial profiles of the sea urchin gut, community DNA was extracted from the gut and pharynx tissues, the gut digesta and egested fecal pellets, as well as the tank water and feed. NextGen amplicon sequencing of the V4 segment of the bacterial 16S rRNA gene, followed by bioinformatics tools were implemented. The results indicate Proteobacteria to be the dominant taxa of the gut microbiome, with members of Campylobacterales dominating in the gut tissue. Oligotyping analysis followed by BLAST determined the Campylobacterales sequence oligotype to be related to Arcobacter species (identity > 91%), from the likely source of the tank water and feed. In the gut digesta and egested fecal pellets, Vibrio was found to be dominant. This study is expected to offer the baseline microbial profile of the sea urchin, L. variegatus, as it may pertain to the digestive physiology of the organism, the ecological impact of the microbe-laden egested fecal pellets onto the various marine trophic levels, and the informed culturability of the healthy sea urchin as a model organism.

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