Differences in chondroitin AC lyase activity of Flavobacterium columnare isolates   总被引：1，自引：1，他引：0  

K M Stringer-Roth  W Yunghans  L F Caslake 《Journal of fish diseases》2002,25(11):687-691

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琥珀酸黄杆菌促生机理及其对多年生黑麦草生长和抗逆性的生理调控作用     

张新飞  佘木子  李晗玉  敬松  姜惠娜  高浩  朱延晓  付娟娟 《草地学报》2021,29(8):1704-1711

为探究琥珀酸黄杆菌（Flavobacterium succinicans）对非生物胁迫下多年生黑麦草（Lolium perenne）的缓解效应,本试验研究了菌株DSM4002的生物学特性,并在盆栽条件下,分析了干旱（维持相对含水量（30±5）%处理7 d和14 d）、低温（4℃处理3 d和7 d）和盐胁迫（150 mM NaCl处理5 d和10 d）下根际接种DSM4002对多年生黑麦草生长和生理特性的影响。结果表明,DSM4002具有分泌吲哚乙酸（Indole-3-acetic acid,IAA）、溶磷和产铁载体能力,对壮观霉素、卡那霉素等具有抗性,对氯霉素敏感。同时,接种DSM4002能够提高正常生长、干旱、低温和盐胁迫下多年生黑麦草的生物量、抗氧化酶活性、可溶性糖和脯氨酸含量,降低相对电导率和丙二醛（Malondialdehyde,MDA）含量。综上,琥珀酸黄杆菌促进多年生黑麦草的生长与其自身具有分泌IAA、溶磷和产铁载体能力有关,而且它能够调节植物体内氧化还原平衡,从而增强多年生黑麦草的抗旱、抗寒和抗盐能力。  相似文献   

The influence of salmon surface mucus on the growth of Flavobacterium columnare     

Staroscik AM  Nelson DR 《Journal of fish diseases》2008,31(1):59-69

Flavobacterium columnare is the causative agent of columnaris disease. The presence of lesions on the gills, skin and fins of diseased fish suggests that F. columnare is able to utilize fish skin mucus as a substrate for growth and that exposure to this material would alter the expression of genes involved in the colonization of the outer surfaces of the fish. Growth, biofilm formation, extracellular protease production and changes in protein expression of F. columnare strain C#2 cultured in media supplemented with juvenile Atlantic salmon skin mucus were compared with the same media without mucus. C#2 was able to grow by using mucus as the sole nutrient source. Growth in mucus-containing media induced cells to grow as a biofilm and extracellular protease activity increased in mucus-containing cultures. SDS-PAGE protein profiles showed that expression of six extracellular proteins increased in mucus-containing media. These results demonstrate that salmon surface mucus promotes the growth of F. columnare and that exposure to mucus alters the growth characteristics of this bacterium with regard to protease production and biofilm formation. Further characterization of mucus-induced physiological changes will increase our understanding of the basis of virulence of this economically important fish pathogen.  相似文献   

安吉白茶对柱状黄杆菌抑菌机理的研究     

吕娜  韦薇  顾帅  庞超  李雪娇  郭畅 《中国畜牧兽医》2015,42(1):136-139

为探讨安吉白茶对柱状黄杆菌的抑菌机理,本试验通过测定安吉白茶提取液与细菌作用前后培养液电导率和紫外吸收物的变化,以及菌体磷代谢和可溶糖的变化,初步阐明了安吉白茶对柱状黄杆菌的抑菌机理。研究结果显示,经安吉白茶提取液处理后,细菌培养液的电导率和可溶糖浓度均增大,菌悬液中的紫外吸收物也随作用时间的延长而增加,表明安吉白茶提取液可破坏细胞膜的结构、导致细胞通透性增加,进而使细胞内容物外泄。此外,经安吉白茶处理后的柱状黄杆菌对磷的消耗量降低,以致严重影响了核酸、磷脂等细胞重要成分的合成及能量代谢,导致细菌正常生理功能的丧失。结果表明,安吉白茶可通过破坏菌体细胞膜及干扰磷代谢等途径抑制柱状黄杆菌的生长。  相似文献   

Flavobacterium psychrophilum in rainbow trout, Oncorhynchus mykiss (Walbaum), hatcheries: studies on broodstock, eggs, fry and environment     

Madsen L  Møller JD  Dalsgaard I 《Journal of fish diseases》2005,28(1):39-47

The occurrence of Flavobacterium psychrophilum at four rainbow trout hatcheries was investigated to provide more knowledge about the reservoirs and transmission of this bacterium. Broodstock were sampled at stripping (including both unfertilized and fertilized eggs), and the offspring were then sampled at the eyed egg and fry stages. Water and surface samples (e.g. hatchery trays) were also sampled. Flavobacterium psychrophilum was found in ovarian fluid and milt, indicating that broodstock may serve as a reservoir and are latent carriers of the pathogen. Flavobacterium psychrophilum was not found on or inside eggs, but further egg studies will be necessary to elucidate the possibility of vertical transmission of the pathogen. Flavobacterium psychrophilum was isolated from water samples, but only from water that had been in close contact with farmed rainbow trout or eggs. Flavobacterium psychrophilum isolates were characterized and compared with well-characterized strains, using degradation of elastin, serotype and ribotype profiles. Different ribotypes of F. psychrophilum were found between hatcheries, but a common ribotype A was found at all four hatcheries. Different ribotypes were found in broodstock without clinical disease, whereas only a few ribotypes (mostly ribotype A) were found in diseased fry. The same ribotype A was found in broodstock, in water samples from hatchery trays and in fry, which suggests the possibility of transmission of F. psychrophilum between broodstock and offspring.  相似文献   

Quantification of Flavobacterium psychrophilum in rainbow trout, Oncorhynchus mykiss (Walbaum), tissues by qPCR     

Orieux N  Bourdineaud JP  Douet DG  Daniel P  Le Hénaff M 《Journal of fish diseases》2011,34(11):811-821

A qPCR assay was developed for rapid and sensitive detection of Flavobacterium psychrophilum, the aetiological agent of bacterial cold-water disease and rainbow trout fry syndrome in salmonid fish worldwide. A set of F. psychrophilum-specific primers based on 16S rRNA gene sequences was designed and validated for specific detection and quantification of DNA isolated from representative strains of F. psychrophilum. The qPCR assay exhibited a high specificity for the 16S rRNA gene of F. psychrophilum (from 4 × 10(8) down to 11 copies per reaction) but not for other Flavobacterium species or other bacteria including fish pathogens. This qPCR-based method proved to be useful in the quantification of the F. psychrophilum titre present within organs dissected out from diseased fish. As the F. psychrophilum genome contains six copies of the 16S rRNA gene, we could infer a limit of detection corresponding to two bacteria per reaction, corresponding to 800 bacteria per fish tissue sample, and therefore 20 F. psychrophilum cells mg(-1) of tissue (for sample weighing 40 mg). The qPCR assay reported here could be a useful tool for veterinary diagnostic laboratories to monitor the F. psychrophilum infection level in fish farms.  相似文献   

Feed deprivation of channel catfish, Ictalurus punctatus (Rafinesque), influences organosomatic indices, chemical composition and susceptibility to Flavobacterium columnare     

Shoemaker CA  Klesius PH  Lim C  Yildirim M 《Journal of fish diseases》2003,26(9):553-561

Withholding feed has been suggested as a strategy to manage infectious disease of channel catfish, Ictalurus punctatus (Rafinesque). In a previous study, we demonstrated that deprivation of feed for as little as 7 days reduced innate resistance of catfish to Flavobacterium columnare. This study was conducted to evaluate the effect of feeding regimens [no feeding (NF), fed once every other day to satiation (FEOD) and fed once daily to satiation (FD)] on organosomatic indices, physiological changes and susceptibility of channel catfish to F. columnare. Fish that were not fed for 2 and 4 weeks had a significant increase (P < 0.05) in gutted weight:-wet weight ratio and decrease in other organosomatic indices [gut index (GI), mesenteric fat index (MFI) and hepatosomatic index (HSI)]. Haematology was not effected by feeding regimen except at week 4, when a significantly higher haemoglobin level was observed in the NF fish. Serum protein did not differ at week 2, but the level at week 4 of the NF fish (35.91 mg mL(-1)) was significantly lower than that of the FD fish (41.77 mg mL(-1)). Significantly lower (P < 0.05) blood glucose (39.5 and 40.3 mg dL(-1)) and liver glycogen (1.7 and 1.8 mg g(-1)) were seen in the NF fish at weeks 2 and 4, respectively, as compared with blood glucose and liver glycogen levels of FD fish (67.5 and 92.8 mg dL(-1) and 46.5 and 52.6 mg g(-1) at weeks 2 and 4, respectively) and FEOD (82.8 and 85.5 mg dL(-1) and 45.1 and 51.4 mg g(-1) at weeks 2 and 4, respectively). Mortality in the NF fish caused by F. columnare (78%) was significantly higher (P < 0.05) than mortality in the FD and FEOD treatments (0.0 and 1.7%, respectively). Blood glucose and liver glycogen showed the same trend of low values for NF fish following challenge (week 6). Blood glucose, liver glycogen, GI and HSI are sensitive indicators for channel catfish deprived of feed (NF) for 4 weeks. Blood glucose and liver glycogen levels around 40 mg dL(-1) and 2 mg g(-1), respectively, are indicative of starvation in juvenile channel catfish. Moreover, NF fish were susceptible to F. columnare infection. Thus, it is suggested that in the absence of natural food, juvenile channel catfish should be fed at least once every other day to apparent satiation to maintain normal physiological function and improve resistance to F. columnare.  相似文献   

Effect of biofilm formation on antimicrobial tolerance of Flavobacterium psychrophilum     

Sundell K  Wiklund T 《Journal of fish diseases》2011,34(5):373-383

Treatment of bacterial fish diseases can be complicated by resistant bacterial biofilms harbouring pathogenic bacteria and causing recurrent exposure of fish to infections. In this study, the effect of biofilm formation on antimicrobial tolerance was examined using three bacterial isolates of the fish pathogen Flavobacterium psychrophilum and two antimicrobial agents, oxytetracycline and flumequine, commonly used in aquaculture. Planktonic and biofilm cells were exposed to a minimum inhibitory concentration (MIC), to a 3 × MIC concentration and to an environmental concentration level of each antimicrobial in 96-well microtitre plates after which growth on agar plates was measured. The type strain NCIMB1947 of F. psychrophilum was further used to study the development of antimicrobial resistance in biofilm cells. The results suggest that at high bacterial densities (>10(7) CFU mL(-1)), biofilm cells of F. psychrophilum are less susceptible to antimicrobial agents. Furthermore, the results imply that biofilm cells of F. psychrophilum may rapidly develop resistance to both oxytetracycline and flumequine if exposed to subinhibitory concentrations of these antimicrobials.  相似文献   

Characterization of serum and mucosal antibody responses and relative per cent survival in rainbow trout, Oncorhynchus mykiss (Walbaum), following immunization and challenge with Flavobacterium psychrophilum   总被引：1，自引：0，他引：1  

B R LaFrentz  S E LaPatra  G R Jones  J L Congleton  B Sun  K D Cain 《Journal of fish diseases》2002,25(12):703-713

Serum and mucosal antibody responses of juvenile rainbow trout, Oncorhynchus mykiss, were characterized by enzyme‐linked immunosorbent assay (ELISA) following immunization with various preparations of formalin‐killed Flavobacterium psychrophilum cells. The protective nature of these preparations was then determined by immunizing rainbow trout fry and challenging with the bacterium. Juvenile rainbow trout immunized intraperitoneally (i.p.) with formalin‐killed F. psychrophilum emulsified with Freund's complete adjuvant (FCA), and i.p. with formalin‐killed F. psychrophilum either with or without culture supernatant generated significant serum antibody responses by 6 and 9 weeks, respectively. Significant mucosal antibody responses were detected by 9 weeks only in fish immunized i.p. with killed F. psychrophilum/FCA. Following immunization and bacterial challenge of rainbow trout fry, protective immunity was conferred in F. psychrophilum/FCA and saline/FCA groups with relative per cent survival values of up to 83 and 51, respectively. Significant protection was not observed in treatment groups immunized by immersion or i.p. without adjuvant at the challenge doses tested. Results suggest that stimulation of non‐specific immune factors enhances the ability of fish to mount a protective immune response, but specific antibody appears necessary to provide near complete protection. In this study, an ELISA was developed to monitor anti‐F. psychrophilum antibody production in trout. The relationship of such responses to protective immunity suggests that future vaccination strategies against coldwater disease may require stimulation of both the innate and adaptive arms of the immune response.  相似文献   

虎纹蛙白内障病病原的分离鉴定及其免疫防治          下载免费PDF全文

周永灿  朱传华等 《上海海洋大学学报》2001,(1):16-21

本文报道了海南养殖虎纹蛙白内障病病原及其免疫学防治方法。对该典型患病个体进行病原分离并鉴定表明，被分离出的病原为脑膜炎败血黄杆菌。在所实验的20种抗菌药物中，该菌只对万古霉素敏感，对头孢哌酮中度敏感，而对其他18种药物均不敏感。通过筛选该病原强毒株制备甲醛灭活疫苗，对健康虎纹蛙进行免疫接种后，可明显提高其对该病的抵抗能力，表明在生产上用免疫学方法防治该病是可行的。  相似文献