Our study aimed at searching for the pathogenic factor causing Siberian sturgeon (Acipenser baerii) disease.A pathogenetic bacterial strain X-1-06909 was isolated from naturally infected Siberian sturgeon in Beijing. The strain was identified according to its physiological and biochemical properties, and the sequence analysis of 16S rRNA gene. The drugs sensitivity was detected with Kirby-Bauer's agar diffusion method.Based on the result of 16S rRNA sequence analysis, the strain X-1-06909 shares 99.6% sequence identity with the type strain ATTCC35624(T) of Aeromonas veronii. The morphological characteristics of the strain were gram-negative, polar single-flagella. The results of physiological and biochemical tests were that the strain could ferment glucose and produce gas, methyl red (M-R) and Voges-Proskauer (V-P) tests were positive, arginine dihydrolase test was negative, it grew on 3% sodium chloride culture medium, the tests for hydrolysis of gelatin and hydrolysis of esculin were negative. The result for drug sensitive tests showed that among 21 antibiotics, cefadroxil, neomycin etc. had better inhibitive effect on the strain.The isolated strain X-1-06909 was identified as A. veronii. The results will provide evidences for further caring the diseases of sturgeons.
Abstract Background: Siberian sturgeon (Acipenser baeri Brandt) and Beluga sturgeon (Huso huso) are two important commercial fish in China, and the feeding habits of them are very different. Diets and feeding habits are two significant factors to affect the gastrointestinal microbiota in fish. The intestinal microbiota has been reported to play a key role in nutrition and immunity. However, it is rarely reported about the relationship between the intestinal microbiota and feeding habits/diets on different Acipenseridae fish. This study is to comparative analysis of gut microbial community in two different Acipenseridae fish fed with the same diet/the same fish with different diets in order to realize the effects of different feeding habits/diets on the intestinal microflora of fish. Results: According to the experimental objectives, BL and BH groups were Beluga sturgeon (Huso huso) fed with low fishmeal diet and high fishmeal diet, respectively. SH group represented Siberian sturgeon (Acipenser baeri Brandt) fed with the same diet as BH group. After 16 weeks feeding trial, the intestinal microbiota was examined by 16S rRNA high-throughput sequencing technology. On the phylum level, Proteobacteria and Bacteroidetes were significantly higher in BL group than BH group, and Cyanobacteria showed the opposite trend. Compared with BH group, Proteobacteria and Firmicutes were significantly increased in SH group, whereas Cyanobacteria were clearly decreased. At the genus level, Pseudomonas and Citrobacter in BL group were significantly higher comparing with BH group, while Bacillus, Luteibacter, Staphylococcus and Oceanobacillus was lower in BH group than SH group. Conclusions: Alpha and beta diversities indicated that the intestinal microflora were significant difference between Siberian sturgeon and Beluga sturgeon when they fed with the same diet. Meanwhile, Beluga sturgeon fed with low fishmeal diet can increase the species diversity of intestinal microbiota than it fed high fishmeal diet. Therefore, feeding habits clearly affected the gastrointestinal microbiota of sturgeons. Moreover, the impact of changes in food on the gut microbiota of sturgeons should be taken into consideration during the process of sturgeon aquaculture.
Abstract Background Siberian sturgeon ( Acipenser baeri Brandt) and Beluga sturgeon ( Huso huso ) are two important commercial fish in China, and the feeding habits of them are very different. Diets and feeding habits are two significant factors to affect the gastrointestinal microbiota in fish. The intestinal microbiota has been reported to play a key role in nutrition and immunity. However, it is rarely reported about the relationship between the intestinal microbiota and feeding habits/diets on different Acipenseridae fish. This study is to comparative analysis of gut microbial community in Siberian sturgeon and Beluga sturgeon fed with the same diet/Beluga sturgeon fed with different diets in order to determine the effects of different feeding habits/diets on the fish intestinal microbiota. Results According to the experimental objectives, BL and BH groups were Beluga sturgeon ( Huso huso ) fed with low fishmeal diet and high fishmeal diet, respectively. SH group represented Siberian sturgeon ( Acipenser baeri Brandt) fed with the same diet as BH group. After 16 weeks feeding trial, the intestinal microbiota was examined by 16S rRNA high-throughput sequencing technology. On the phylum level, Proteobacteria and Bacteroidetes were significantly higher in BL group than BH group, and Cyanobacteria showed the opposite trend. Compared with BH group, Proteobacteria and Firmicutes were significantly increased in SH group, whereas Cyanobacteria were clearly decreased. At the genus level, Pseudomonas and Citrobacter in BL group were significantly higher comparing with BH group, while Bacillus , Luteibacter , Staphylococcus and Oceanobacillus was lower in BH group than SH group. Conclusions Alpha and beta diversities indicated that the intestinal microflora were significant difference between Siberian sturgeon and Beluga sturgeon when they fed with the same diet. Meanwhile, Beluga sturgeon fed with low fishmeal diet can increase the species diversity of intestinal microbiota than it fed high fishmeal diet. Therefore, feeding habits clearly affected the gastrointestinal microbiota of sturgeons. Moreover, the impact of changes in food on the gut microbiota of sturgeons should be taken into consideration during the process of sturgeon aquaculture.
A feeding experiment was carried out to determine the effects of dietary carotenoid source on body color, skin and scale pigmentation, antioxidant responses of blood porrot (Cichlasoma synspilum â × Cichlasoma citrinellum â). Seven experimental diets were formulated as following: the control diet without carotenoids; PO diet with 4.0 g/kg paprika oleoresin, HP diet with 2.0 g/kg Haematococcus pluvialis, PR diet with 2.0 g/kg Phaffia rhodozyma, AS diet with 0.4 g/kg synthetic astaxanthin, CA diet with 1.0 g/kg β-carotene and POL diet with 2.0 g/kg paprika oleoresin + 3.0 g/kg lutein. Each experimental diet was fed to triplicate groups of fish to visual satiation twice per day for 8 weeks. The results showed that AS diet turn fish body red higher and sooner, followed by PR diet and HP diet, successively (P < 0.05). PO and CA had no significant effect on improving body color, but POL diet can turn fish color yellow effectively (P < 0.05). Astaxanthin concentration in diet is positively correlated with redness a*, but negatively with lightness L*. Diet lutein is positive linear correlation with yellowness b*. All carotenoids can significantly reduce plasma superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and lipid peroxide (LPO) level, but increase total antioxidant capacity (T-AOC). The present results suggest that dietary inclusion of 0.4 g/kg synthetic astaxanthin can improve body color effectively and quickly, and all test carotenoid source can increase antioxidant activities of blood parrot.
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Bacterial ghost,a novel inactivated non-denatured bacterium,is intact bacterial envelope which is lysised by the lysis gene E of PhiX174.Bacterial ghost has been researched as fish bacteria vaccine just in recent 8 years.It not only has high biological safety,but also can induce humoral and cellular immunity.So bacterial ghost is possible to be used in oral immunization and has a unique advantage in fish vaccine.Much more attention has been paid on ghost being used as a recombinant vaccine or drug delivery system.This paper summarizes the international latest developments in fish bacterial ghost vaccine,discusses their immune response and protective effect in different immunization ways using different strategies.
Infectious hematopoietic necrosis virus (IHNV) is the most important pathogen threatening the aquaculture of salmonid fish in China. In addition to the common genogroup J IHNV, genogroup U has been newly discovered in China. However, there is no effective DNA vaccine to fight against this emerging genogroup U IHNV in China. In this study, DNA vaccines encoding the IHNV viral glycoprotein (G) gene of the GS2014 (genogroup J) and BjLL (genogroup U) strains isolated from northern China were successfully developed, which were identified by restriction analysis and IFA. The expression of the Mx-1 gene and G gene in the spleens and muscles of the injection site as well as the titers of the serum antibodies were measured to evaluate the vaccine efficacy by RT-qPCR and ELISA. We found that DNA vaccine immunization could activate Mx1 gene expression and upregulate G gene expression, and the mRNA levels of the Mx1 gene in the muscles were significantly higher than those in the spleens. Notably, DNA vaccine immunization might not promote the serum antibody in fish at the early stage of immunization. Furthermore, the efficacy of the constructed vaccines was tested in intra- and cross-genogroup challenges by a viral challenge in vivo. It seemed that the DNA vaccines were able to provide great immune protection against IHNV infection. In addition, the genogroup J IHNV-G DNA vaccine showed better immune efficacy than the genogroup U IHNV-G or divalent vaccine, which could provide cross-immune protection against the genogroup U IHNV challenge. Therefore, this is the first study to construct an IHNV DNA vaccine using the G gene from an emerging genogroup U IHNV strain in China. The results provide great insight into the advances of new prophylactic strategies to fight both the genogroup J and U IHNV in China.
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