Characteristics of culturable bacteria associated with tail fan necrosis in the spiny lobster, Jasus edwardsii

Abstract

Tail fan necrosis (TFN) is an increasingly common condition found in commercially-fished and aquacultured spiny lobsters. Chitin, lipid, and protein are the major components of the lobster cuticle, and we test whether bacteria proteolytic, chitinolytic, and lipolytic activities are associated with the presence of TFN in spiny lobsters. Bacteria were cultured from the surface of the tail fans and from the hemolymph of wild Australasian red spiny lobsters, Jasus edwardsii (Hutton, 1875), with TFN and from those without any signs of TFN. The proteolytic, chitinolytic, and lipolytic activities of 1678 bacteria isolates were characterized using standard plating methods. Chitinolytic bacteria strains were more common on the tail fans and in the hemolymph of lobsters with TFN compared with those without TFN, and the overall chitinolytic activity of bacteria present in lobsters with TFN was higher than in lobsters without TFN. The bacteria isolates with a combination of proteolytic, chitinolytic and lipolytic activities were more prevalent on the tail fans and in the hemolymph of lobsters with TFN. Molecular methods identified 14 bacteria species from 35 isolates possessing this broad enzymatic profile associated with TFN with over 50% of the isolates belonging to four species in the Splendidus clade of Vibrio, which are known aquatic pathogens. Collectively these results suggest a suite of bacteria exhibiting proteolytic, chitinolytic and lipolytic activities were associated with TFN in lobsters. These bacteria may be competitively advantaged in the opportunistic infection of sites of physical damage to the protective cuticle in spiny lobsters.