14 research outputs found

    Competition on Using Nutrient for Growth between Bacillus spp. and Vibrio harveyi

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    ABSTRACT Competition, by using nutrient for growth, between Bacillus pumilus NW01, B. sphaericus NW02 and B. subtilis NW03 and Vibrio harveyi in vitro was studied by culturing each bacteria in Nutrient Broth (+ 1.5% NaCl). The initial concentration of 10 2 CFU/ml in monoculture and co-culture of Bacillus spp. and V. harveyi was used. Total Bacillus and Vibrio counts were conducted after 0, 24, 48, 72, 96 and 120 hours. B. pumilus NW01, B. sphaericus NW02 and B. subtilis NW03 decreased V. harveyi by 39.10, 43.62 and 34.46%, respectively. Antagonistic properties of Bacillus spp. against V. harveyi in vivo was tested by feeding shrimp with spores (10 11 -10 12 CFU/g) of each Bacillus and their mixture at 5 g/kg for 1 month. The amount of Vibrio spp. in the intestine of all Bacillus treated shrimp decreased by 20.97-32.45 % as compared with the control. The results showed that these Bacillus spp. could be applied as an effective probiotic in Penaeus monodon culture

    Identification and Antibiotic Sensitivity Test of the Bacteria Isolated from Tra Catfish (Pangasianodon hypophthalmus [Sauvage, 1878]) Cultured in Pond in Vietnam

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    ABSTRACT Tra catfish (Pangasianodon hypophthalmus [Sauvage, 1878]) cultured in Vietnam is one of the most important products for export to international market such as U.S.A., Japan and Europe. The bacterial isolation was conducted from pond-cultured Tra catfish in the provinces with intensive culture system. There were a total of 97 isolates from 65 diseased fish. Sixty-six isolates from 97 isolates were identified by biochemical tests. They were consisted of Edwardsiella ictaruli (58 isolates [87.9%]), Aeromonas hydrophila (2 isolates [3.03%]) and 6 unidentified isolates (9.07%). Antibiotic sensitivity test was also conducted to determine the drugs that could be used to control these two bacteria. Effective drugs that showed good sensitivity against E. ictaluri were ciprofloxacin, amoxycillin and ampicillin, florfenicol, doxycycline and oxytetracycline (in order of number of isolates that showed sensitive). Two isolates of Aeromonas hydrophila were sensitive to sulphamethoxazole, ciprofloxacin, oxytetracycline, enrofloxacin, erythromycin, sulphamethoxazole/trimethoprim, doxycycline and florfenicol

    Comparative study of the effects of Montanide™ ISA 763A VG and ISA 763B VG adjuvants on the immune response against Streptococcus agalactiae in Nile tilapia (Oreochromis niloticus)

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    Acknowledgements We are highly grateful to thank Seppic, France, for providing us with the commercial products of MontanideTM ISA 763A VG and MontanideTM 437 ISA 763B VG. Funding This research project was financially supported by Mahasarakham University (Grant No. 6517022Peer reviewedPostprin

    Effect of putative probiont Enterococcus hirae on the haematological parameters of juvenile African catfish, Clarias gariepinus (Burchell, 1822) during pre- and post-challenge against Aeromonas hydrophila

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    Probiotics have been widely known to have the ability to improve the immune system of livestock and aquatic animal. The present study was carried out to evaluate the effect of dietary supplementation of two probiotic isolates of Enterococcus faecium on hematological parameters of juvenile African catfish, Clarias gariepinus during pre- and post-challenge with aquatic pathogen, Aeromonas hydrophila. The probiotics were previously isolated from vegetable wastes (mung bean sprouts, Vigna radiate and cucumber, Cucumis sativus) which have been fermented for 7 days. The experimental fish (270 tails) with an average weight of 5.13 ± 1.03 g were distributed and divided randomly into i) control (30 tails), fed with commercial diet ii) E1 (30 tails), fed with diets supplemented with 108 CFU/ml of E. faecium isolated from fermented cucumber, iii) E2 (30 tails), fed with 108 CFU/ml of E. faecium isolated from fermented mung bean sprouts. The feeding trial was conducted for 50 days. All experimental groups were then challenged with A. hydrophila (1.5 × 106 CFU/mL) via intraperitoneal injection on day 51. Prior to challenge, blood samples were collected from five fish randomly selected from each group on the day 51 (pre-challenge). After 72 hours of post-challenge, blood samples were again collected from five fish from each groups. The hematological parameters such as total erythrocyte count (RBC), total leucocyte count (WBC), packed cell volume (PCV), hemoglobin (Hb), the derived blood indices of mean corpuscular volume (MCV) and corpuscular hemoglobin concentration (MCHC) were examined. Hematological profiles of pre- and post-challenge infected juvenile catfish were compared with the control groups. The RBC, Hb, WBC, PCV, MCV and MCHC of fish fed with probiotics showed higher significant difference (P<0.05) as compared to control groups during pre- and post-challenge of pathogen. The high level of RBC and WBC during pre- and post-challenge showed the capability of the probiotics to improve the immune response of juvenile African catfish and thus increased the fish disease resistance against A. hydrophila infection. The result suggested that E. faecium could be used effectively as a probiotic in aquaculture

    Characterization, Stress Response and Functional Analyses of Giant River Prawn (Macrobrachium rosenbergii) Glucose-Regulated Protein 78 (Mr-grp78) under Temperature Stress and during Aeromonas hydrophila Infection

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    The endoplasmic reticulum (ER) is an organelle important for several functions of cellular physiology. This study identified the giant river prawn’s glucose-regulated protein 78 (Mr-grp78), which is important for ER stress mechanisms. Nucleotide and amino acid analyses of Mr-grp78, as compared with other species, revealed the highest similarity scores with the grp78 genes of crustaceans. An expression analysis by quantitative RT-PCR indicated that Mr-grp78 was expressed in all tissues and presented its highest expression in the ovary (57.64 ± 2.39-fold), followed by the gills (42.25 ± 1.12), hindgut (37.15 ± 2.47), thoracic ganglia (28.55 ± 2.45) and hemocytes (28.45 ± 2.26). Expression analysis of Mr-grp78 mRNA levels under Aeromonas hydrophila induction and heat/cold-shock exposure was conducted in the gills, hepatopancreas and hemocytes. The expression levels of Mr-grp78 in these tissues were highly upregulated 12 h after bacterial infection. In contrast, under heat- and cold-shock conditions, the expression of Mr-grp78 was significantly suppressed in the gills at 24–96 h and in the hepatopancreas at 12 h (p &lt; 0.05). A functional analysis via Mr-grp78 gene knockdown showed that Mr-grp78 transcription in the gills, hepatopancreas and muscle strongly decreased from 6 to 96 h. Furthermore, the silencing of this gene effectively increased the sensitivity of the tested prawns to heat- and pathogenic-bacterium-induced stress. The results of this study clearly demonstrate the significant functional roles of Mr-grp78 in response to both temperature and pathogen treatments

    Molecular Identification and Dual Functions of Two Different CXC Chemokines in Nile Tilapia (Oreochromis niloticus) against Streptococcus agalactiae and Flavobacterium columnare

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    Two CXC chemokines in Nile tilapia (On-CXC1 and On-CXC2) were identified at both the genomic and proteomic levels. A southern blot analysis and comparison searching in Ensembl confirmed the typical structure of the CXC chemokine genes and provided evidence for unusual mechanisms used to generate the two different CXC chemokine transcripts that have not been reported in other vertebrate species so far. The expression levels of On-CXC1 and On-CXC2 were analyzed by quantitative real-time PCR. These two mRNAs were detected in various tissues of normal Nile tilapia, especially in the spleen, heart, and head kidney, indicating a homeostatic function in immunosurveillance. A time-course experiment clearly demonstrated that these two transcripts were effectively enhanced in the head kidney, spleen and trunk kidney of Nile tilapia 6, 12 and 24 h after injection with Streptococcus agalactiae but were down-regulated in all tested tissues at 48 h, reflecting the fact that they have short half-lives during the crucial response to pathogens that is characteristic of CXC chemokine genes in other vertebrates. Functional analyses obviously exhibited that these two CXC chemokines at concentrations of 1&ndash;10 &mu;g strongly inactivated S. agalactiae and Flavobacterium columnare and effectively induced phagocytosis of leukocytes in vitro

    Probiotic Effects of a Novel Strain, Acinetobacter KU011TH, on the Growth Performance, Immune Responses, and Resistance against Aeromonas hydrophila of Bighead Catfish (Clarias macrocephalus Günther, 1864)

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    In the present study, the novel probiotic strain Acinetobacter KU011TH with an evident lack of pathogenicity in catfish was experimented. Three practical administration routes, namely, feed additive (FD), water-soluble additive (SOL), and a combination route (FD+SOL), were applied in two sizes of catfish. After 120 days of FD+SOL administration, catfish fingerlings (15 g) exhibited a significant improvement in all tested growth performance parameters. For 15- and 30-day applications at the juvenile stage (150 g), phagocytic activity, phagocytic index, lysozyme activity, respiratory burst activity, alternative complement pathway, and bactericidal activity were significantly increased. Furthermore, probiotic-administered bighead catfish exhibited an upregulated expression of several immune-related genes in tested organs. Significant colonization by Acinetobacter KU011TH in rearing water and on skin and gills was observed among experimental groups. Histological analysis clearly indicated enhanced physical characteristics of skin mucosal immunity in the treated groups. No histopathological changes in the gills, skin, intestine or liver were observed among the fish groups. Interestingly, after challenge with Aeromonas hydrophila, the survival rates of the treated groups were significantly higher than those of the controls. In conclusion, the novel probiont Acinetobacter KU011TH provides a potent strategy for improvement in growth and disease resistance, which is an important steppingstone for sustaining catfish aquaculture

    Development of a Monoclonal Antibody Specific to the IgM Heavy Chain of Bighead Catfish (Clarias macrocephalus): A Biomolecular Tool for the Detection and Quantification of IgM Molecules and IgM+ Cells in Clarias Catfish

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    Catfish is a commonly-cultivated freshwater fish in Thailand and many Southeast Asian countries. The molecular data obtained for the IgM heavy chain (IgMH) of catfish have been useful for distinguishing monoclonal antibodies (mAbs). A mAb specific to C&mu;1 of the IgMH of catfish (IgMHC&mu;1 mAb) was developed in a rabbit model using sequence information from bighead catfish (Clarias macrocephalus). The IgMHC&mu;1 mAb strongly recognized the IgM heavy chain of the tested catfish, namely, bighead catfish, African catfish (Clarias gariepinus) and their hybrid (C. macrocephalus &times; C. gariepinus), in immunological Western blot analysis and competitive ELISAs. Additionally, the IgMHC&mu;1 mAb successfully recognized IgM+ cells by detecting IgM molecules in both secreted and membrane-bound forms in peripheral blood leukocytes (PBLs). The IgMHC&mu;1 mAb was further used to quantify the percentage of IgM+ cells among PBLs through flow cytophotometry. The IgM+ cell percentages of healthy bighead catfish, African catfish and their hybrid were 38.0&ndash;39.9%, 45.6&ndash;53.2%, and 58.7&ndash;60.0%, respectively. Furthermore, the IgMHC&mu;1 mAb showed no cross-reactivity with the IgM of zebrafish. These findings suggest that this mAb can be used as an immunological tool for monitoring the health, immune status, and immune development of cultivated Clarias catfish

    Antibacterial and Antiviral Activities of Local Thai Green Macroalgae Crude Extracts in Pacific White Shrimp (Litopenaeus vannamei)

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    Macroalgae are potentially excellent sources of bioactive secondary metabolites useful for the development of new functional ingredients. This study was conducted to determine the antimicrobial efficacy of the hot water crude extracts (HWCEs) of three species of local Thai green macroalgae Ulva intestinalis (Ui), U. rigida (Ur), and Caulopa lentillifera (Cl) and a commercial ulvan from U. armoricana (Ua). Chemical analysis indicated that the HWCE of Ur showed the highest sulfate content (13.9% &plusmn; 0.4%), while that of Ua contained the highest uronic acid and carbohydrate contents (41.47% &plusmn; 4.98% and 64.03% &plusmn; 2.75%, respectively), which were higher than those of Ur (32.75% &plusmn; 1.53% and 51.02% &plusmn; 3.72%). Structural analysis of these extracts by Fourier-transform infrared (FTIR) spectroscopy revealed that these HWCEs are complex with a signal at 1250 cm&minus;1 corresponding to S=O stretching vibrations, while the signals at 850 cm&minus;1 were attributed to the C&ndash;O&ndash;S bending vibration of the sulfate ester in the axial position. These HWCEs showed the growth suppression against some pathogenic Vibrio spp. Interestingly, the HWCEs from Ui at concentrations of 5 and 10 mg/mL completely inhibited white spot syndrome virus (WSSV) in shrimp injected with HWCE&ndash;WSSV preincubated solutions. This inhibitory effect was further confirmed by the reduction in viral loads and histopathology of surviving and moribund shrimp

    Acinetobacter Strain KUO11TH, a Unique Organism Related to Acinetobacter pittii and Isolated from the Skin Mucus of Healthy Bighead Catfish and Its Efficacy Against Several Fish Pathogens

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    The bacterial strain KU011TH was isolated from the skin mucus of healthy bighead catfish. The strain is a Gram-negative coccobacillus that is nonmotile, aerobic, catalase positive, oxidase negative, and nonhemolytic. Sequence analyses of the housekeeping genes 16S rRNA, gyrB and rpoB indicate that this strain is a new member of the Acb complex of the genus Acinetobacter and is closely related to Acinetobacter pittii and Acinetobacter lactucae. In addition, the genome relatedness-associated ANIb (&lt;95&ndash;96%) and in silico DDH (&lt;70%) values clearly supported the new member of the genus Acinetobacter and the Acb complex. The genome of the strain KU011TH was approximately 3.79 Mbp in size, comprising 3619 predicted genes, and the DNA G+C content was 38.56 mol%. The major cellular fatty acids were C18:1&omega;9c, C16:0, C16:1, C20:2, C18:2&omega;6c and C18:1&omega;9t. The whole-genome sequences and phenotypic, phylogenetic, and chemotaxonomic data clearly support the classification of the strain KU011TH as a new member in the genus Acinetobacter which is closest to A. pittii. Additionally, the new bacterial strain exhibited strong activity against a broad range of freshwater fish pathogens in vitro
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