Dominant intestinal microflora of sea bream and sea bass larvae, from two hatcheries, during larval development (original) (raw)
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Journal of Fish Diseases, 2012
The location and cell damage caused by Vibrio anguillarum, the causative agent of classical vibriosis, within the developing gut of the newly hatched sea bass, Dicentrarchus labrax (L.), is unknown. A gnotobiotic sea bass model was used to investigate the early interactions of V. anguillarum with sea bass larvae. In the present study, germ-free sea bass larvae were orally exposed to a V. anguillarum HI-610 pathogen labelled with the green fluorescent protein (GFP-HI-610) and sampled at regular intervals. Pathogenic colonization of gut enterocytes was observed 2 h post-exposure (p.e.) and onwards, whereas bacteria within the swim bladder were visualized 48 h p.e and onwards. Ultrastructural findings demonstrated direct bacterial contact with the host cell in the oesophageal mucosa and putative attachment to microvilli of mid-and hindgut enterocytes. The present findings form a starting point for studies assessing the impact of potential candidates (probiotics, prebiotics, antimicrobial peptides) to mitigate bacterial virulence.
Prevalence of Vibrio species on fish from pelagic and demersal habitats
FISHERY …, 2002
The density and diversity in the vibrio species on the body parts of some commercially important fishes of India were studied with respect to the habitat viz pelagic and demersal. The distribution of vibrios on fish from these habitats showed wide variations both quantitatively and qualitatively. The results indicate that the density of vibrios on the skin and gills may be more in pelagic fish compared to demersal types. However the intestinal count of vibrios is similar in the two categories. The species diversity was more in the demersal fishes particularly in the intestinal samples.The vibrio species were in the order of dominance as V. alginolyticus, V. orientalis, and V. campbelli. Species like V. alginolyticus, V. parahaemolyticus, V. vulni ficus and V. mimicus were among the pathogenic species isolated from the fish samples. The study reveals that vibrios constitute a major portion of the total bacterial flora in tropical fish.
Journal of Applied Microbiology, 2009
Aims: Vibrio populations in the seawater supply and the water of seven exhibition aquaria that simulate various Mediterranean and tropical ecosystems were compared. The similarity of Vibrio populations in the intestine of various fish species, feed and water was examined. Resistance to the antibiotics used in fish health management was analysed for the dominant Vibrio isolates. Methods and Results: Samples were collected for 1 year from seven exhibition tanks reproducing different ecosystems. The diversity and population similarity among vibrios were determined using a miniaturized biochemical phenotyping method. Similar Vibrio populations were found in the water supply and in the water of the Mediterranean ecosystems. However, different Vibrio populations were found in the water of tanks with tropical ecosystems. Vibrio populations in the water seemed to have a greater effect on the composition of intestinal Vibrio populations than those in feed. No resistance to antibiotics was observed, indicating their appropriate use for health management. Conclusions: Water characteristics have a greater impact on the composition of Vibrio populations in aquaria and fish intestinal microbiota than bacteria in feed. Significance and Impact of the Study: The microbiological monitoring water could provide valuable information for managing the health of exhibition aquaria.
Fisheries and aquatic sciences, 2013
Vibrio ichthyoenteri is a facultatively anaerobic gram-negative bacterium with straight or slightly curved rod morphology. The bacterium is an etiological agent of bacterial enteritis of Olive flounder Paralichthys olivaceus. Only a handful of studies, using a limited number of isolates, have investigated the phenotypic and genetic characteristics of V. ichthyoenteri. We isolated 40 V. ichthyoenteri strains, identified based on the 16S rRNA gene sequence, from the diseased flounder larvae and investigated the API 20E and ZYM profiles. The isolates exhibited highly divergent phenotypic characteristics regardless of sampling time point and location, and fish age. Essential enzymes produced by V. ichthyoenteri seemed to be alkaline phosphatase, leucine arylamidase, and N-acetyl-β-glucosaminidase. This study reveals a much greater enzymatic and biochemical phenotype diversity than has been evident to date. These results suggest that a given population of V. ichthyoenteri could be heterogeneous in terms of its phenotypic characteristics.
Asian Fisheries …, 2004
Hatchery produced Asian sea bass Lates calcarifer (Bloch) juveniles (120 days post hatch) maintained in a fish hatchery, Central Institute of Brackishwater Aquaculture (CIBA), were used in the present study. Diseased and moribund fish showed haemorrhages at the bases of dorsal, pectoral and anal fins. The affected fish stopped taking food. Bacteria isolated from the aseptic kidney samples drawn from the moribund fish belonged to the genus Vibrio as evidenced through selective growth on TCBS agar. Colony morphology, growth and the biochemical characteristics suggested that the bacterium was Vibrio anguillarum-like (VAL). This VAL bacterium, injected at varying doses in Liza macrolepis and Oreochromis mossambicus revealed LD 50 end points of 10 4.17 and 10 5.47 CFU, respectively. Exposure of L. calcarifer juveniles to graded levels of virulent bacterium via injection and bath showed that a cell density of 10 4.5 CFU/fish and 10 6.3 CFU per ml, respectively, can kill half of the exposed population. Investigations carried out on the histopathology of the infected fish indicated severe necrotic degenerative changes in the gills with mild to extensive lamellar fusion and hyperplasia of naturally infected seabass juveniles, while that of the experimentally infected fish showed no discernible changes. Natural infection showed wide spread chronic histopathological manifestations while, the experimental infection accounted for acute phase pathogenesis -related manifestations. reported to have accounted for £11 million . Vibrio spp was responsible for a phenomenal 67.8% of the bacterial diseases of gilt-head seabream, collected from south-western Spain during 1990. Vibriosis is a serious problem in farmed seabass (L. calcarifer) in Singapore (Cheong et al. 1983), Thailand (Chinabut and and Australia (Glazebrook and Campbell 1986). First success in India, of induced maturation and breeding of the Asian seabass was achieved by the Central Institute of Brackishwater Aquaculture in 1997. Since then, the species has attracted much attention of the coastal aquaculturists in India. Identification of potential pathogens of farmed seabass is of immense importance. Isolation, identification, characterization, virulence and histopathology of infection of Vibrio spp. isolated from farm produced Asian seabass (L. calcarifer) are discussed in this paper. Tilapia and mullet are among the important brackishwater species as forage and food fish. Hence, susceptibility of these species to varying doses of exposure to VAL bacterium was tested and histopathologies of experimental and natural infection in L. calcarifer are discussed in the present paper.
Fish & Shellfish Immunology, 2017
The aim of this study was to assess the effects of low levels of dietary fish meal (FM) and fish oil (FO) on disease resistance and gut associated lymphoid tissue (GALT) response after an experimental intestinal infection with V. anguillarum in European sea bass (Dicentrarchus labrax) For that purpose, sea bass juveniles were fed one of four diets containing combined levels of FO and FM as follows: 20%FM/6%FO, 20%FM/3%FO, 5%FM/6%FO and 5%FM/3%FO during 153 days. At the end of the feeding trial, fish were subjected to either an in vivo exposure to a sub-lethal dose of V. anguillarum via anal inoculation or to an ex vivo exposure to V. anguillarum. Additionally, inducible nitric oxide synthase (iNOS) and tumor necrosis factor (TNF) gut patterns of immunopositivity were studied. Growth performance was affected by dietary FM level, however ex vivo gut bacterial translocation rates and survival after the in vivo challenge test were affected by dietary FO level. After 5 months of feeding, low dietary FM levels led to a posterior gut up-regulation of interleukin-1 (IL-1) and TNF, major histocompatibility complex-II (MHCII) and cyclooxygenase-2 (COX2), which in turn reduced the gut associated lymphoid tissue (GALT) capacity of response after 24h post infection and conditioned European sea bass capacity to recover gut homeostasis 7 days post infection. Immunoreactivity to anti-iNOS and anti-TNF presented a gradient of increased immunopositivity towards the anus, regardless of the dietary FM/FO fed. Strong positive anti-TNFα isolated enterocytes were observed in the anterior gut in relation to low levels of dietary FM/FO. Submucosa and lamina propria immunoreactivity grade was related to the amount of leucocyte populations infiltrated and goblet cells presented immunopositivity to anti-iNOS but not to anti-TNFα. Thus, reducing FO content from 6% to a 3% by VO in European sea bass diets increases ex vivo and in vivo gut bacterial translocation rates, whereas reducing FM content from 20% down to 5% up-regulates the expression of several posterior gut inflammationrelated genes conditioning fish growth and GALT capacity of response after bacterial infection.
Turk. J. Vet. Anim. Sci, 2010
Th e aim of this study was to determine the dominant aerobic bacterial community of sea bass larvae during their weaning period in 2 diff erent marine hatcheries in Muğla-Bodrum region. Samplings were made in January, March, and May 2005. Larvae and water samples were diluted in certain ratios and were inoculated to Marine Agar, TCBS Agar, Pseudomonas Agar, King Bee Agar, MRS agar, Blood Agar and Plate Count Agar, in that order. Water temperature, pH, saturation, salinity, and features of the system used were recorded.
Journal of Applied Microbiology, 2009
Aims: To develop a SYBR Green quantitative real-time PCR protocol enabling detection and quantification of a fish probiotic and two turbot pathogenic Vibrio spp. in microcosms. Methods and Results: Phaeobacter 27-4, Vibrio anguillarum 90-11-287 and Vibrio splendidus DMC-1 were quantified as pure and mixed cultures and in presence of microalgae (Isochrysis galbana), rotifers (Brachionus plicatilis), Artemia nauplii or turbot (Psetta maxima) larvae by real-time PCR based on primers directed at genetic loci coding for antagonistic and virulence-related functions respectively. The optimized protocol was used to study bioencapsulation and maintenance of the probiont and pathogens in rotifers and for the detection and quantification of Phaeobacter and V. anguillarum in turbot larvae fed rotifers loaded with the different bacteria in a challenge trial. Conclusions: Our real-time PCR protocol is reproducible and specific. The method requires separate standard curve for each host organism and can be used to detect and quantify probiotic Phaeobacter and pathogenic Vibrio bioencapsulated in rotifers and in turbot larvae. Significance and Impact of the Study: Our method allows monitoring and quantification of a turbot larvae probiotic bacteria and turbot pathogenic vibrios in in vivo trials and will be useful tools for detecting the bacteria in industrial rearing units.
Fish Physiology and Biochemistry, 2009
The everted gut sac technique has been used to investigate the effect of Vibrio vulnificus on water and electrolyte (Na+, K+, Cl−, HCO3−) transport on the intestine of sea bream (Sparus aurata L.). Both the anterior and the posterior intestine were incubated in a medium containing 108V. vulnificus cells ml−1 at 25°C for 2 h. The presence of V. vulnificus resulted in a significant reduction (P < 0.05) of water absorption in the anterior intestine, while sodium absorption in the anterior (P < 0.01) and posterior (P < 0.05) intestine was elevated. Chloride absorption was increased, but the changed was not significant, while potassium absorption decreased significantly (P < 0.05), but only in the posterior intestine. Incubation the sea bream intestine with V. vulnificus did not affect carbonate secretion in the anterior segment, whereas high secretion was stimulated in the posterior segment (P < 0.01). Histological evaluations demonstrated damage in the anterior intestine of sea bream that was characterized by the detachment of degenerative enterocytes, alterations in the microvilli, and the presence of a heterogenous cell population, indicating inflammation. Based on our results, we conclude that V. vulnificus caused cell damage to the intestine of sea bream and that the anterior intestine is more susceptible than the posterior part of the intestine. Several hypotheses are suggested to explain our observations, such as the presence of higher numbers of villosities in the anterior intestine than in the posterior one and/or the presence of endogenous bacteria in the posterior intestine which may have a protector role.