Lesion bacterial communities in American lobsters with diet-induced shell disease

Abstract

In southern New England, USA, shell disease affects the profitability of the American lobster Homarus americanus fishery. In laboratory trials using juvenile lobsters, exclusive feeding of herring Clupea harengus induces shell disease typified initially by small melanized spots that progress into distinct lesions. Amongst a cohabitated, but segregated, cohort of 11 juvenile lobsters fed exclusively herring, bacterial communities colonizing spots and lesions were investigated by denaturing gradient gel electrophoresis of 16S rDNA amplified using 1 group-specific and 2 universal primer sets. The Bacteroidetes and Proteobacteria predominated in both spots and lesions and included members of the orders Flavobacteriales (Bacteriodetes), Rhodo bacterales, Rhodospirillales and Rhizobiales (Alphaproteobacteria), Xanthomonadales (Gamma proteobacteria) and unclassified Gammaproteobacteria. Bacterial communities in spot lesions displayed more diversity than communities with larger (older) lesions, indicating that the lesion communities stabilize over time. At least 8 bacterial types persisted as lesions developed from spots. Aquimarina 'homaria', a species commonly cultured from lesions present on wild lobsters with epizootic shell disease, was found ubiquitously in spots and lesions, as was the 'Candidatus Kopriimonas aquarianus', implicating putative roles of these species in diet-induced shell disease of captive lobsters.

Fine-scale transition to lower bacterial diversity and altered community composition precedes shell disease in laboratory-reared juvenile American lobster

“…This finding is counter to previously reported genetic fingerprinting results that showed differences in the bacterial communities among lesions and spots (Quinn et al 2012b). Based on their initial findings, Quinn et al (2012b) suggested that the bacteria present in a spot may be important in initiating shell disease in lobsters, whereas bacteria found in lesions were secondary, opportunistic colonizers that thrived in the new conditions. The lack of differenti- ation between lesion and spot communities in our data suggests that this may not be the case.…”

“…Although we only recovered a single OTU that was associated with the genus Aquimarina (OTU 18), we recovered several other OTUs, including Lutimonas, that were from the Flavobacteria family (Table 1). Several studies have reported that members of this family aside from Aquimarina are important to epizootic shell disease (Chistoserdov et al 2012, Meres et al 2012, Quinn et al 2012b). In addition to Aquimarina, the 'Thalassobius' genus has been associated with epizootic shell disease (Meres et al 2012, Quinn et al 2012a).…”

“…Initial investigation of the bacteria associated with epizootic shell disease identified a few key members of the shell microbiome ; however, this study was based on culturing techniques, which typically assess less than 1% of the bacterial community (Staley & Konopka 1985). Later studies based on cultureindependent fingerprinting methods eliminated this culture bias; however, those studies did not fully characterize the bacterial community associated with both healthy and diseased shell throughout the progression of the disease (Chistoserdov et al 2012, Quinn et al 2012b. A higher resolution sequencing study using next-generation sequencing techniques identified 170 different bacterial species associated with the lobster shell, an order of magnitude more than previous studies (Meres et al 2012).…”

“…Lobsters were housed in conditions sim-ilar to those described in prior shell disease re search (Chistoserdov et al 2012, Quinn et al 2012b, Tlusty & Metzler 2012. Briefly, all lobsters were kept in individual 9 cm diameter containers (hereafter referred to as pens) and fed a diet consisting of Economac-4™ (Aqua fauna Bio-Marine), a commercially available shrimp feed.…”

Possible shell disease in 100 million-year-old crabs

“…In epizootic shell disease, 2 specific pathogens are suspected (Chistoserdov et al 2012), and infection appears to be triggered by a higher than usual temperature (Quinn et al 2012a, Tlusty & Metzler 2012. Similar pathogens are observed in lesions produced by impoundment and endemic shell disease, but not in cases of diet-induced shell disease (Chistoserdov et al 2012, Quinn et al 2012b. Remarkably, integument lesions of crabs only occasionally harbor the 2 lobster pathogens, but Vibrio and Pseudoalteromonas spp.…”