Normal bacterial flora of the spiny lobster Panulirus argus and its possible role in shell disease

Abstract

Recent surveys of the Caribbean spiny lobster (Panulirus argus) in the Florida Keys and the Dry Tortugas revealed the presence of necrotic carapace lesions, which are commonly associated with bacterial shell disease in other crustaceans. To determine the etiology of these lesions, we obtained bacterial samples from diseased and nondiseased lobsters. Bacteria from these samples were isolated and identified by 16S ribosomal RNA sequencing. At least 600 bases of the 16S rRNA gene were aligned with sequences from known strains of marine bacteria. The analysis showed that the majority of the strains isolated from diseased and nondiseased lobsters are within the Vibrionaceae, a common family of marine bacteria. The majority of isolates identified as Vibrio species are clustered in a monophyletic group that does not include any of the known Vibrio species. Genbank BLAST analysis also confirmed these isolates as Vibrio and confirmed that they are not closely related to any known Vibrio species. These results suggest that the normal flora of P. argus is unique. The association of these bacteria both with lesions and with nondiseased animals suggests that the natural flora is responsible for the lesions seen in P. argus.