Characterization of Bacteria Associated With Lobster Shell Disease.

Abstract

Lobster shell disease is a condition that affects the outer three layers of a lobster’s carapace and results in dramatic lesions of the exoskeleton. The causative agents of lobster shell disease are believed to consist of chitinoclastic bacteria. For the present study, bacteria associated with lobster shell disease in the New England region were identified, based on 16s rDNA sequences. American lobsters, Homarus americanus, with shell disease were collected from Rhode Island, Connecticut, Massachusetts, and Maine. Bacteria were isolated from lesions and individually cultured. Genomic DNA was extracted from the bacteria, and two primers were used (Fwd; 5 AGA GTT TGA TCH TGG CTY AG 3: Rev; 5 ACG GNT ACC TTG TTA CGA CTT 3) to amplify a segment (1500 bp) of the 16s rDNA. Individual bands were cloned and sequenced at the Josephine Bay Paul Center of the Marine Biological Laboratory using the facility’s protocols. Sequences were identified based on sequence homology using NCBI’s BLAST server. A majority of the bacteria identified belonged to the Cytophaga-Flavobacter and Alpha proteobacteria groups. Other bacteria identified included members of the Oceanobacillus, Staphylococcus, and Vibrio genera. Results indicate that there could be specific geospatial distribution patterns for certain bacteria isolated. For example, most Cellulophaga species were found in Maine, and the Oceanobacillus species was detected in a Rhode Island lobster. These data suggest that bacterial species belonging to the CytophagaFlavobacter and Alpha proteobacteria groups are most likely the causative agents of lobster shell disease, because nearly all samples collected contained bacteria related to these groups.