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1.
6种中草药对4种淡水鱼致病菌体外抑菌作用的研究   总被引：4，自引：0，他引：4  
研究了6种中草药对4种淡水鱼致病菌温和气单胞菌（Aerom onas sobria）、嗜水气单胞菌（A.hydrophila）、生物Ⅰ-荧光假单胞菌（Pseudom onas fluorescentb iotypeⅠ）和柱状黄杆菌（Flavobacterium columnaris）的体外抑菌作用。以黄连（Coptis chinensis）、大黄（Rhem officinale）、连翘（Forsythia suspensa）、鱼腥草（Houttuynia corda-ta）、厚朴（Magnolia officinalis）和大青叶（Folium isatidis）6种中草药的水提物为研究对象,采用滤纸片法检测其对4种致病菌的抑制活性,并分别测定了这6种植物提取物对供试菌的最小抑菌浓度（M IC）。结果表明,黄连水提物对4种淡水鱼致病菌的抑菌效果最好,大黄和连翘水提物次之,而鱼腥草、厚朴和大青叶水提物的抑菌效果不明显。  相似文献   

2.
Motile aeromonad septicaemia caused by Aeromonas sobria is a cause of disease in farmed perch, Perca fluviatilis L., in Switzerland. We have evaluated the potential of a Pseudomonas chlororaphis isolate, obtained from perch intestine, to control A. sobria infection. Inoculation of juvenile perch with P. chlororaphis strain JF3835 prior to infection with A. sobria caused a reduction in A. sobria associated mortalities. Infection of perch with xylE -labelled P. chlororaphis indicated the bacterium is able to transiently colonize juvenile fish and fingerlings.  相似文献   

3.
Aeromonas isolates were collected from cultured fish, characterized phenotypically and identified to species using 16S rDNA. The pathogenicity of all isolates was assayed on the basis of haemolytic and proteolytic activity and challenge tests were performed for isolates from healthy fish. A total of 131 Aeromonas isolates were obtained and identified as follows: A. hydrophila (13), A. bestiarum (23), A. salmonicida (motile biogroup) (19), A. caviae (2), A. sobria (18), A. veronii bt. sobria (42), A. jandaei (1), A. encheleia (11) and A. allosaccharophila (2). All isolates of A. hydrophila and A. bestiarum and most isolates of A. salmonicida and A. veronii were classified as pathogenic. Aeromonas hydrophila was isolated only from diseased trout except for one isolate obtained from carp fry. The other potentially pathogenic Aeromonas species were present in diseased as well as healthy fish. The pathogenicity of isolates from healthy fish was correlated with their enzymatic activity and was also tested by challenge experiments. The dominant pathogenic species were A. veronii bt. sobria, A. bestiarum and A. salmonicida in common carp and A. hydrophila in rainbow trout.  相似文献   

4.
Significant numbers of perch, Perca fluviatilis, raised on a pilot fish farm in Switzerland presented focal skin lesions on the lateral sides and fin rot. Mortality rates reached levels of up to 1% of the total fish on the farm per day. Virtually pure cultures of Aeromonas sobria were isolated from the liver, kidney, spleen and skin lesions of affected fish. Aeromonas sobria isolated from the farmed perch had a haemolytic effect on sheep and trout erythrocytes, autoaggregated, was cytotoxic for cultured fish cells and possessed genes involved in type III protein secretion. Experimental infection of naive perch with a single colony isolate of A. sobria from an affected farm fish resulted in the development of clinical signs identical to those seen on the farm. The results indicate that A. sobria can act as a primary pathogen of perch.  相似文献   

5.
为了解斑点叉尾(鮰)(Ictalurus punctatus)"腹水症"的发病原因,提高防控技术,试验在佛山市某渔场患典型"腹水症"的病(鮰)上分离出优势菌落,通过形态学观察、生化及分子生物学鉴定确定该细菌为温和气单胞菌(Aeromonas sobria).通过对健康斑点叉尾(鮰)的回归感染实验发现,与原感染鱼发病症状相似,且分离鉴定得到相同病原菌.体外药敏试验结果显示:该温和气单胞菌菌株对恩诺沙星、氟苯尼考等7种药物敏感,而对四环素、强力霉素耐药.本研究还探讨了4种芽孢杆菌对分离的温和气单胞菌的拮抗作用,结果表明地衣芽孢杆菌对该病原的拮抗作用最好.  相似文献   

6.
Nanotechnology is an emerging avenue employed in disease prevention and treatment. This study evaluated the antimicrobial efficacy of chitosan nanoparticles (CSNPs) against major bacterial and oomycete fish pathogens in comparison with chitosan suspension. Initially, the minimum inhibitory concentrations (MIC, MIC90) were determined and the per cent inhibition of bacterial growth was calculated. Subsequently, the minimum bactericidal concentrations (MBCs) were determined. The time-dependent disruptions of CSNP-treated pathogens were observed via transmission electron microscopy (TEM), and the effect of CSNPs on the viability of two fish cell lines was assessed. No antimicrobial effect was observed with chitosan, while CSNPs (105 nm) exhibited a dose-dependent and species-specific antimicrobial properties. They were bactericidal against seven bacterial isolates recording MBC values from 1 to 7 mg/ml, bacteriostatic against four further isolates recording MIC values from 0.125 to 5 mg/ml and fungistatic against oomycetes recording MIC90 values of 3 and 4 mg/ml. TEM micrographs showed the attachment of CSNPs to the pathogenic cell membranes disrupting their integrity. No significant cytotoxicity was observed using 1 mg/ml CSNPs, while low dose-dependent cytotoxicity was elicited by the higher doses. Therefore, it is anticipated that CSNPs are able to compete and reduce using antibiotics in aquaculture.  相似文献   

7.
Abstract. Seven fish pathogenic isolates of Aeromonas hydrophila , one A. sobria and one A. caviae were investigated for production of the fish lethal acetylcholinesterase toxin (AcChE-toxin). Western blotting was used for screening the ECP of these strains with a rabbit antiserum prepared against the purified toxin of strain B32 and all the isolates (except A. sobria ) gave positive results with different patterns of bands. The AcChE-toxin appears to be secreted as a protein of high molecular weight which is stable at −20°C, and in 90% of the strains tested, it appears to be split into lower molecular weight fragments by the action of other components present in the ECP. The smallest, stable and highly active fragment has a MW of 15kDa.  相似文献   

8.
Populations of aerobic heterotrophic bacteria present in the gastrointestinal (GI) tract of healthy Atlantic cod (Gadus morhua L.) fed three different diets, fish meal, standard or a bioprocessed soybean meal (BPSBM), were estimated using the dilution plate technique. A total of 944 isolates were characterised by biochemical and physiological properties and 425 isolates were identified further by sequencing the 16S rRNA genes. Our results showed that gut microbiota were affected by dietary manipulation. The GI tract of fish fed fish meal was dominated by Gram-positive bacteria of the genera Brochothrix and Carnobacterium. The Gram-negative bacteria Chryseobacterium spp. and Psychrobacter glacincola, and Gram-positive bacteria belonging to Carnobacterium, dominated in the digestive tract of fish fed soybean meal. In contrast to these results, genus Psychrobacter dominated in the GI tract when fish were fed BPSBM.Until recently, it was generally suggested that the gut microbiota of fish were less diverse than in homoeothermic animals. However, the present study identified several “new” bacterial species isolated from the alimentary tract of Atlantic cod. These “new” bacterial species are not normally isolated from the GI tract of fish. Based on our finding we suggest that the GI tract microbiota of fish might not be as simple as believed.Antagonistic activity of carnobacteria regarding inhibition of growth of two fish pathogens (Aeromonas salmonicida ssp. salmonicida and Vibrio anguillarum) was observed. However, some difference in the antibacterial activity of Carnobacterium spp. was observed. Whether this antagonistic activity has any effect in challenge studies will be discussed, especially in relation to the finding that the digestive tract is one of the major infection routes in fish.  相似文献   

9.
细菌性疾病是中国海水养殖鲆鲽类的主要病害,为全面了解病原菌种类,本研究对1999~2012年从山东、江苏、河北、天津等沿海地区养殖场发病鲆鲽鱼类中分离得到的124株优势菌株进行了16S rRNA基因测序和系统发育学分析。将基因序列与GenBank核酸序列数据库进行相似度比对分析,结果显示,有83株与弧菌属(Vibriosp.)细菌相似度最高,11株与气单胞菌属(Aeromonas sp.)细菌相似度最高,4株与爱德华氏菌属(Edwardsiella sp.)细菌相似度最高,26株为其他15种属的细菌。根据系统发育学分析结果,进一步将66株菌鉴定为16个种,优势种为溶藻弧菌(V.alginolyticus)、哈氏弧菌(V.harveyi)、鳗弧菌(V.anguillarum)、杀鲑气单胞菌(A.salmonicida)和迟缓爱德华氏菌(E.tarda)。选择其中的9株鳗弧菌和4株迟缓爱德华氏菌进行人工感染实验,结果显示,其中7株鳗弧菌和3株迟缓爱德华氏菌对大菱鲆(Scophthalmus maximus)有较强的致病性。研究结果可为阐明中国海水养殖鲆鲽类的流行病发生历史、病原种类、病原监测及疾病控制提供重要参考。  相似文献   

10.
Abstract. The in vitro bacteriostatic activity of a combination of sulphadiazine (SDZ) and trimethoprim (TMP) against representative bacterial fish pathogens was studied. In general, the minimum inhibitory concentrations (MIC) of TMP were much smaller than comparable values for SDZ. When SDZ and TMP were combined, the bacteriostatic effect was enhanced in a synergistic manner for all bacteria tested except Pseudomonas fluorescens . The synergism was most remarkable in the case of bacterial strains that were sensitive to the action of SDZ alone. This degree of synergism was observed when the ratios of SDZ and TMP in combination were in the range of 1:1 io 5:1. The MIC of SDZ plus TMP combined was less than 3.13 μg/ml for SDZ resistant strains and as low as 0.2 to 0.78 μ/ml for SDZ sensitive strains. The possible usefulness of a combination of these two compounds for therapy or control of bacterial fish disease is discussed.  相似文献   

11.
ABSTRACT:   Fourteen bacterial strains isolated from marine environments exhibited antagonistic action against a wide range of bacteria including Vibrio spp. A double layer agar method was used for preliminary screening to determine the relative degree of growth inhibition or bacteriolysis exhibited by the isolates. Most of the antagonistic isolates were found to be Gram-negative, motile rods and were oxidase positive, and oxidative in the oxidation and fermentation test, suggesting that they are belong to the genera Pseudomonas . The antagonistic isolates lyzed the dead cells of marine Gram-negative bacteria in both plate and liquid methods. Bacteriolytic and casein hydrolytic activities were observed in the culture supernatant of the isolates. Anion exchange column chromatography (Toyopearl DEAE-650 M) was used to purify the extracellular protease produced by an antagonistic strain A1-J25a. The active fractions of protease collected from the eluted solution also exhibited bacteriolytic activity.  相似文献   

12.
The aim of this study was to evaluate probiotic properties and the aflatoxin B1 adsorption ability of yeasts isolated from rainbow trout intestine and fish feed to assess their use in the formulation of feed additives. Growth at pH 2, bacterial pathogens inhibition, bacterial pathogens co‐aggregation, autoaggregation, homologous and heterologous inhibition against lactic acid bacteria were evaluated. Moreover, aflatoxin B1 adsorption was tested. All strains were able to maintain viable (107 cells/ml) at pH 2. All strains isolated from intestine were identified as Kazaschtania exigua, while strains isolated from feed were all identified as Debaryomyces hansenii. Kazaschtania exigua RC035 and RC037 showed the strongest antimicrobial activity while K. exigua RC037 and RC038 were the most efficient co‐aggregating bacterial pathogens. All strains exhibited strong autoaggregation. None of the tested yeast strains showed homologous inhibition towards other yeasts and heterologous inhibition towards lactic acid bacteria strains. Debaryomyces hansenii RC031 demonstrated aflatoxin B1 adsorption capacity (21%). The results of the present study indicate that select strains of Kazaschtania exigua and D. hansenii showed potential to improve the health of rainbow trout by inhibiting pathogens and binding AFB1 and their use as probiotics may improve the production of rainbow trout in aquaculture systems.  相似文献   

13.
Michigan's fisheries rely primarily upon the hatchery propagation of salmonid fish for release in public waters. One limitation on the success of these efforts is the presence of bacterial pathogens, including Aeromonas salmonicida, the causative agent of furunculosis. This study was undertaken to determine the prevalence of A. salmonicida in Michigan fish, as well as to determine whether biochemical or gene sequence variability exists among Michigan isolates. A total of 2202 wild, feral and hatchery‐propagated fish from Michigan were examined for the presence of A. salmonicida. The examined fish included Chinook salmon, Oncorhynchus tshawytscha (Walbaum), coho salmon, O. kisutcha (Walbaum), steelhead trout, O. mykiss (Walbaum), Atlantic salmon, Salmo salar L., brook trout, Salvelinus fontinalis (Mitchill), and yellow perch, Perca flavescens (Mitchill). Among these, 234 fish yielded a brown pigment‐producing bacterium that was presumptively identified as A. salmonicida. Further phenotypic and phylogenetic analyses identified representative isolates as Aeromonas salmonicida subsp. salmonicida and revealed some genetic and biochemical variability. Logistic regression analyses showed that infection prevalence varied according to fish species/strain, year and gender, whereby Chinook salmon and females had the highest infection prevalence. Moreover, this pathogen was found in six fish species from eight sites, demonstrating its widespread nature within Michigan.  相似文献   

14.
采用通用引物PCR配合SSCP和RFLP技术检测鱼病病原菌   总被引：8，自引：0，他引：8  
彭宣宪 《水产学报》2000,24(4):345-348
采用通用引物PCR（UPPCR）、PCR－RFLP、PCR－SSCP技术,研究快速鉴别鱼病病原菌的分子生物学诊断技术。结果发现,采用细菌16S rRNA基因保守区特异性引物,以嗜水气单胞菌、鲁克氏耶尔森菌、鳗弧菌、柱状曲挠杆菌、乙型链球菌、荧光假单胞菌等部分常见鱼病病原菌为对象,可以建立一种UPPCR技术。该技术能在保证实验条件不变的基础上,检出上述所有细菌,并还可检出大肠杆菌和双歧杆菌等非鱼病病原菌。并且认为,该法与SSCP配合即采用UPPCR－SSCP技术能较好地鉴别被检菌而用于鱼病病原菌的快速诊断。  相似文献   

15.
鳖保宁对中华鳖气单胞菌病的药效学研究   总被引：7，自引：2，他引：7  
采用常规方法对中华鳖（Trionyx sinensis)常见病害进行细菌学检查，测定了鳖保宁及相关单味药对中华鳖主要病原菌温和气单胞菌（Aeromonas sobria)和豚鼠气单胞菌（A.caviae)的最低抑菌浓度（MIC）和最低杀菌浓度（MBC），并观察鳖保宁预防鳖病害的效果，结果表明：20例患病鳖中共分离到28株细菌，其中温和气单胞菌和豚鼠气单胞菌分别占32.14%和21.43%;鳖保宁及相关单味药对温和气单胞菌和豚鼠气单胞菌均有不同程度的抑制和杀灭作用。其中鳖保宁的作用最强；鳖保宁预防鳖病害的效果优于对照组。  相似文献   

16.
研究从患病蝶尾金鱼(Butterfly)肝脏中分离获得的1株病菌,为金鱼疾病防治提供参考。分离纯化获得1株细菌,编号为DW-1,通过细菌形态观察、理化特性、16S rDNA序列分析等方法进行鉴定。结果表明DW-1菌株为革兰氏阴性短杆菌,可发酵葡萄糖产气,赖氨酸脱羧酶、硝酸盐还原等为阳性;进一步通过PCR方法扩增16S rDNA序列,测得长度为1 385 bp,与维氏气单胞菌(Aeromonas veronii)相似性为99%~100%;构建系统发育树与维氏气单胞菌温和生物变种(A.veronii biovar sobria)模式菌株ATCC9071聚为一支。最终鉴定该菌株为维氏气单胞菌温和生物变种。人工感染试验结果表明,对斑马鱼半数致死量(LD_(50))为1.17×10~6CFU/m L。药敏试验结果显示该菌株对头孢克肟、头孢哌酮、链霉素、恩诺沙星、诺氟沙星、左氟沙星、复方新诺明等23种药物敏感。  相似文献   

17.
A monitoring program for Vibrio harveyi and other potential bacterial pathogens of summer flounder was conducted at two facilities in the Northeast United States. Bacterial samples were collected from larval and juvenile fish and live-feed, and identified using API 20E biochemical profiles and 16S rDNA sequencing. Histopathological examinations were conducted in order to relate histological changes with the presence of potential bacterial pathogens. V. harveyi, Vibrio ichthyoenteri, and Photobacterium damselae subsp. damselae, three known pathogens of flatfish, were isolated from diseased summer flounder. Although a high proportion of juvenile summer flounder showed microscopic signs of disease, the presence of these potential bacterial pathogens in fish was not associated with large-scale mortalities. An outbreak of flounder infectious necrotizing enteritis with 30% cumulative mortality occurred when juveniles were transported to a new facility. Isolates of V. harveyi from the disease outbreak were genetically different from the isolates from the commercial hatchery. V. harveyi isolates from both facilities were pathogenic to summer flounder by intraperitoneal injection. P. damselae subsp. damselae, V. ichthyoenteri, and Vibrio scophthalmi, also found in fish with gross lesions, were not pathogenic to juvenile summer flounder by intraperitoneal injection. Our research shows that several potential bacterial pathogens are associated with morbidity and mortality in summer flounder larvae and juveniles, especially in situations of stress. Increased knowledge about the environmental conditions that lead to disease, as well as the interactions of V. harveyi with other microbial species, could lead to the development of management strategies in summer flounder farms.  相似文献   

18.
During a 2-year period, bacterial fish pathogens were monitored on five rainbow trout, Oncorhynchus mykiss (Walbaum), freshwater farms in Denmark. A total of 1206 fish were examined and 361 bacterial isolates were identified phenotypically. Enteric redmouth disease, furunculosis and rainbow trout fry syndrome/coldwater disease were recorded. Infections caused by Flavobacterium psychrophilum occurred most frequently, but only one outbreak of enteric redmouth disease caused by Yersinia ruckeri serotype O1 and one of furunculosis caused by Aeromonas salmonicida were recorded during the monitoring period. Flavobacterium psychrophilum was isolated on all farms, both during disease outbreaks and from fish without any signs of disease. Serological investigations of F. psychrophilum showed that serotype Th was the dominant serotype found. The serotypes Th and Fd were involved in disease outbreaks of fry and larger fish. All isolates of F. psychrophilum showed proteolytic activities; however, a few isolates, belonging to serotype FpT did not degrade elastin and were not associated with mortality. Increasing resistance problems to oxytetracycline were demonstrated. More than half of the F. psychrophilum isolates showed resistance to oxolinic acid and oxytetracycline. No antibiotic resistant isolates were found among Y. ruckeri and A. salmonicida .  相似文献   

19.
In this study, 342 bacterial strains were isolated from the gut of channel catfish Ictalurus punctatus. Two different screening strategies, including the production of antagonistic effects against pathogens and the capacity of secreting exoenzyme, were used to select potential probiotics from the bacterial strains. Among them, 6 isolates showed antagonism against the pathogens, 15 isolates could produce high amylase and protease, and 3 isolates (BHI344, BH0142 and BH03124) had both the two characteristics . Then, BHI344, BH0142, and BH03124 were tested for survival rate in channel catfish bile and at low pH, antimicrobial susceptibilities, and pathogenicity in channel catfish. The results of the obtained assays showed that BHI344 possessed the broadest inhibitory potential, a strong ability of secreting extra-cellular amylase and protease, high viability in simulated gastrointestinal conditions, and sensitivity to most of the used antibiotics and non-pathogenic to channel catfish. Therefore, it could be selected as the most promising probiotics candidate. BHI344 was identified as Bacillus subtilis based on the phenotypic characterization and 16S rRNA gene sequencing.  相似文献   

20.
A non-virulent Carnobacterium sp., designated strain K1, isolated from the gastrointestinal tract of Atlantic salmon, Salmo salar L., which produced inhibitory substances against bacterial fish pathogens, was examined in vitro for characteristics important for the colonization of the fish gastrointestinal tract and in vivo for persistence in the tract after oral dosing. In vitro growth experiments showed that the cells of this strain were metabolically active in both the intestinal mucus and faeces from salmonids. The production of growth inhibitors against the two common fish pathogens Vibrio anguillarum and Aeromonas salmonicida by Carnobacterium sp. strain K1 was demonstrated in vitro in mucus and faecal extracts. Furthermore, it was demonstrated that the Carnobacterium cells remained viable in the gastrointestinal tract for several days and that no detrimental effect to the fish was observed as a result of the presence of the bacterium.  相似文献   

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