Shell disease syndrome in the edible crab, Cancer pagurus - isolation, characterization and pathogenicity of chitinolytic bacteria (original) (raw)
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Bacterial septicaemia in prerecruit edible crabs, Cancer pagurus L
Journal of Fish Diseases, 2013
Juvenile edible crabs, Cancer pagurus L., were surveyed from Mumbles Head and Oxwich Bay in South Wales, UK, and the number of heterotrophic bacteria and vibrios in the hemolymph was determined. The percentage of crabs with hemolymph containing bacteria was variable over the survey with higher numbers of animals affected in summer than in winter. Post-moult crabs contained significantly higher numbers of heterotrophic bacteria in the hemolymph than pre-and intermoult animals. Crabs with cuticular damage to the gills also had significantly higher numbers of bacteria in the hemolymph. Crabs were found to have a high prevalence of infection by the dinoflagellate, Hematodinium. Such animals had significantly fewer bacteria in the blood in comparison with Hematodinium-free animals. Of the 463 crabs surveyed, only 3 individuals had hemolymph containing 2000 + CFU mL À1 . Based on 16S rRNA gene sequences, two of these crabs contained a Vibrio pectenicida-like isolate, while the other had a mixed assemblage of vibrios. Although 59% of the crabs surveyed had culturable bacteria in the hemolymph, the majority only had small numbers (<2000 CFU mL À1 ), suggesting that such infections may be of limited importance to the sustainability of the crab fishery in this region.
Aquaculture, 2002
Crustaceans affected by shell disease syndrome display characteristic black-spot lesions in regions of exoskeletal degradation. Vogan et al. [Dis. Aquat. Org. (2001)] have shown that the severity of shell disease in the edible crab, Cancer pagurus, correlates with an increase in haemocoelic bacterial infections and may therefore serve as an external marker for the internal health of the animal. Therefore, this present study examined if the same crabs with shell disease lesions and varying degrees of bacterial septicaemia also displayed differences in the haemogramme, haemolymph phenoloxidase activity, total protein, copper and urea, as well as haemolymph-derived antibacterial activity, compared to uninfected individuals. A strong correlation was found between the severity of shell disease and a reduction in serum protein, which was further indicative of haemocoelic infection. Levels of copper, urea, phenoloxidase, and antibacterial activity in the haemolymph showed no correlations with the proportion of exoskeletal lesion cover. However, the degree of melanisation of haemolymph samples taken from shell-diseased individuals was less than that seen in disease-free crabs. Total haemocyte counts were unaffected by the disease, although some minor changes were found in the differential counts. Overall, despite having intrahaemocoelic infections, shell disease-affected individuals displayed few changes in the cellular or humoral defence parameters examined. D
Journal of Invertebrate Pathology, 2010
The present research reports the first description of Shell Disease Syndrome in European spiny lobsters Palinurus elephas (Fabricius 1787), which occurred in an experimental aquaculture facility in Sicily (Italy). Both bacterial characterization and histopathological examination of the exoskeleton at site of lesions was carried out. Infected specimens showed tail fan erosions, and in one case uropod ulceration and complete loss of periods. Identified species included: Listonella anguillarum 50.5%, Vibrio parahaemolyticus 27.5% and Vibrio alginolyticus 22%. Microscopic evaluation of lesions indicate the presence of inflammatory responses, which include melanization and pseudomembrane formation, similar to those described for other crustaceans affected by SDS.
Abstract: Vibrio harveyi, Vibrio parahaemolyticus, Pseudoalteromonas piscicida, Staphylococcus epidermidis and Micrococcus luteus were isolated from the gut of blue swimming crab, Portunus pelagicus captured from Strait of Tebrau Johor Malaysia and studied for pathogenicity against the Zoea-1 (Z1 stage) of P. pelagicus. Pathogenic isolates V. harveyi and P. piscicida resulted in 100% mortality at 106 cfu mL-1 and 105 cfu mL-1 after 24 h and 72 h post dose. Conversely, V. parahaemolyticus produced 100% deaths at inoculation 106 cfu mL-1 after 72 h post dose. Cumulative mortality was observed rising with the increase in dose potency of pathogens. S. epidermidis and M. luteus detected with feeble pathogenic characteristics. The LD50 of V. harveyi was 1.2x103 cfu ML-1 (24 h), V. parahaemolyticus was 9.6x105 cfu mL-1 (72 h), P. piscicida was 9.8x103 cfu mL-1 (24 h) and S. epidermidis was 9.8x105 cfu mL-1 (72 h). The mean differences among various pathogenic doses were statistically significant (p<0.05). Susceptibility tests of total 662 isolates were under taken including V. harveyi (n = 180), V. parahaemolyticus (n = 180) and P. piscicida (n = 119), isolates showed mixed trend as multiple resistance and sensitive to antimicrobial agents tested while S. epidermidis (n = 88) and M. Luteus (n = 95) were sensitive to all antibiotics tested. V. harveyi, V. parahaemolyticus and P. piscicida did not show 100% resistance to any of the antibiotics tested. From the results of 14 antibiotics tested, we observed that the highest frequency of single drug resistance in V. harveyi was Streptomycin (89.44%) and sensitive to chloramphenicol (70.55%). Similarly, the highest frequency of single-drug resistance in V. parahaemolyticus was to kanamycin (92.78%) and sensitive to chloramphenicol (93.33%) and P. piscicida was to penicillin (80.67+19.33% intermediate but no sensitive) and sensitive to gentamicin (98.32%). Infections caused by antibiotic resistant pathogens have serious consequences and therapeutic use of tested antibiotic is questionable in larviculture of P. pelagicus.
Emerging Diseases and Epizootics in Crabs Under Cultivation
Frontiers in Marine Science
While most crab production for human consumption worldwide comes from capture fisheries, there is increasing production of selected species using aquaculture-based methods. This is both for the purpose of stock replacement and direct yield for human consumption. Disease has limited the ability to produce larval crabs in commercial hatcheries and this together with suitable feeds, are major hurdles in the sustainable development of cultivation methods. Juvenile and adult crabs are also subject to a range of diseases that can cause severe economic loss. Emerging pathogens/parasites are of major importance to crab aquaculture as they can cause high levels of mortality and are difficult to control. Diseases caused by viruses and bacteria receive considerable attention but the dinoflagellate parasites,Hematodiniumspp., also warrant concern because of their wide host range and lack of control methods to limit their spread. This concise review examines the emerging diseases in several crab...
Effect of Extracellular Products of Pseudoalteromonas atlantica on the Edible Crab Cancer pagurus
Applied and Environmental Microbiology, 2004
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Shell disease in the Freshwater crab, Barytelphusa cunicularis
International Journal of Fisheries and Aquatic Studies, 2014
The current study deals with the isolation and identification of bacterial and fungal pathogens, from lesioned carapace and limb of the freshwater crab Barytelphusa cunicularis, inhabiting the paddy fields of Mananthavady, Wayanad, Kerala. The bacterial flora was isolated by pour plate method and phenotypic identification was made based on morphological features and biochemical tests. The fungal pathogen was isolated from Sabouraud dextrose agar medium and morphologically identified using Lactophenol cotton blue stain. From the infested carapace, bacteria belonging to nine genera Aeromonas, Alcaligenes, Bacillus, Chromobacterium, Enterobacter, Escherichia, Klebsiella, Micrococcus and Pseudomonas and one fungal pathogen Aspergillus sp. were identified. Infested limb showed the presence of Pseudomonas and Escherichia coli. The present study on the isolation and identification of microbes from infested carapace and limb will aid in understanding the pathogen profile and its prevalence ...
A histological study of shell disease syndrome in the edible crab Cancer pagurus
Diseases of Aquatic Organisms, 2001
Shell disease syndrome is characterised by the external manifestation of black spot lesions in the exoskeletons of crustaceans. In the present study, gills, hepatopancreas and hearts from healthy (< 0.05% black spot coverage) and diseased (5 to 15% coverage) edible crabs, Cancer pagurus, were examined histologically to determine whether this disease can cause internal damage to such crabs. There was clear evidence of cuticular damage in the gills of diseased crabs leading to the formation of haemocyte plugs termed nodules. Nephrocytes found within the branchial septa of the gills showed an increase in the accumulation of dark material in their vacuoles in response to disease. In the hepatopancreas, various stages of tubular degradation were apparent that correlated with the severity of external disease. Similarly, there was a positive correlation between the number of viable bacteria in the haemolymph and the degree of shell disease severity. Approximately 21% of the haemolymph-isolated bacteria displayed chitinolytic activity. Overall, these findings suggest that shell disease syndrome should not be considered as a disease of the cuticle alone. Furthermore, it shows that in wild populations of crabs shell perforations may lead to limited septicaemia potentially resulting in damage of internal tissues. Whether such natural infections lead to significant fatalities in crabs is still uncertain.