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1.
In the present study a microtitre plate assay was used to evaluate antagonistic activity of 157 intestinal bacteria belonging to Carnobacterium isolated from Arctic charr (Salvelinus alpinus L.), Atlantic salmon (Salmo salar L.) and wolf fish (Anarhichas lupus L.) against fish pathogenic bacteria. One hundred and forty‐nine strains isolated from Arctic charr fed; (a) different lipid levels and (b) different fatty acids were screened for their ability to inhibit growth of the fish pathogen Aeromonas salmonicida ssp. salmonicida strain AL 2020 (the causative agent of furunculosis). Carnobacterium maltaromaticum and Carnobacterium mobile isolated from fish fed a low‐lipid diet inhibited growth of the pathogen, while none of the Carnobacterium divergens isolated from fish fed the high‐lipid diet had this ability. When Arctic charr was fed different fatty acids, was the frequency of antibacterial ability of C. maltaromaticum highest in strains isolated from fish fed 4%α‐linolenic acid (18:3 n‐3) and lowest in strains isolated from fish fed 4% linoleic acid (18:2 n‐6). Extracellular growth inhibitory compounds harvested in exponential and stationary growth phase from eight carnobacteria strains isolated from three fish species were tested for their ability to inhibit growth of six fish pathogens [A. salmonicida, Vibrio splendidus strain VS11, Vibrio salmonicida strain LFI 315, Vibrio anguillarum strain LFI 317, Moritella (Vibrio) viscosa strain LFI 5000 and C. maltaromaticum (piscicola) CCUG 34645]. The highest antibacterial activity was found when cellular extracts of the producer isolate were harvested in stationary growth phase. Scanning electron microscopy (SEM) investigations of A. salmonicida showed that cell morphology was affected by the inhibitory substance produce by strain 8M851, a Carnobacterium inhibens‐like bacteria.  相似文献   

2.
The aim of the study was to isolate, select, and identify proteolytic lactic acid bacteria (LAB) from chao, a traditional fermented fish from Pangkajene and Kepulauan Regency, South Sulawesi, Indonesia. LAB was isolated by poured plate method. Proteolytic LAB were selected using agar skim milk media. Protease activity of LAB was determined based on the amount of tyrosine released in unit/mL. Proteolytic LAB were identified using API 50 CHL kit and 16S rRNA gene sequence analysis. The result showed that a total of 60 isolates were obtained from chao, and 57% of them were cocci-shape. Fifteen isolates were halotolerant proteolytic LAB. Their R values and protease activity were 2.11–3.39 and 0.267–0.304 U/mL, respectively. Identification by API 50 CHL kit showed that four rod-shape isolates were Lactobacillus plantarum, and two others were Lactobacillus curvatus. Cocci-shape isolates could not be identified as cocci bacterium. Rep-PCR results showed that there were two kinds of bands, namely thick and thin. Two isolates were selected from two types of bands that had the highest R for the analysis of 16S rRNA gene sequences, namely Ags1-3 and Ags7-3. The results showed that Ags1-3 isolate was identified as Lactobacillus plantarum and Ags7-3 as Pediococcus acidilactici.  相似文献   

3.
This study examined the diversity of siderophore‐producing bacteria in the intestinal tracts of coastal fish in Japan and screened candidate bacterial strains for probiotic use in aquaculture. Of the 2637 bacteria isolated from the 27 fish specimens (13 species) and six environmental samples collected in this study, 266 isolates exhibited the ability to produce siderophores. Siderophore producers were detected in the intestines of 18 of the fish specimens caught (68%) at densities of 2.3 × 104–2.3 × 108 CFU g?1, in all three seawater samples at 2.0 × 102–1.3 × 103 CFU mL?1 and in all three sand samples at 2.6 × 101–2.8 × 104 CFU g?1. These findings suggest that siderophore‐producing bacteria are widely distributed in the intestinal tracts of coastal fish and their environments. Analysis of 16S rRNA gene sequences revealed that the siderophore producers belonged to 38 species, of which Vibrio splendidus, Vibrio ichthyoenteri and Vibrio crassostreae accounted for 32.7%, 19.5% and 11.3% of the 266 isolates, respectively, suggesting that these bacteria are indigenous to the intestinal tract of coastal fish. Six bacterial species, Enterovibri norvegicus, Photobacterium leiognathi, Photobacterium phosphoreum, Photobacterium rosenbergii, V. crassostrea and Vibrio scophthalmi were identified as possible candidates for use as probionts in fish aquaculture.  相似文献   

4.
The aims of this study was to assess the effect of two lactic acid bacteria (LAB), Lactobacillus curvatus and Leuconostoc mesenteroides, originally isolated from gastrointestinal (GI) tract of beluga (Huso huso) and Persian sturgeon (Acipenser persicus), respectively, on growth, survival and digestive enzyme (amylase, lipase and protease) activities and the population level of LAB in the GI tract. The treatments included 10 different groups; control, separate supplements of L. curvatus and Leu. mesenteroides at three different counts [2 × 109, 5 × 109 and 9 × 109 colony forming units (CFU) per gram food] and three combinations of the two LAB (2 × 109 + 2 × 109, 5 × 109 + 5 × 109 and 9 × 109 + 9 × 109 CFU per gram food). The bacteria used in this study were added in lyophilized form to chopped Chironomidae. In the beluga study, highest specific growth rate, survival and improved intestinal enzyme activities were noted in the rearing group fed 9 × 109 L. curvatus per gram food. In Persian sturgeon, the inclusion level of 2 × 109 Leu. mesenteroides had similar positive effect. The ability of LAB to colonize the digestive tract seems to involve host specificity, and our bacteriological results are relevant to initiate future probiotic studies in sturgeons and future directions will be discussed.  相似文献   

5.
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 108 V. 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.  相似文献   

6.
The aim of this study was to investigate the load and distribution patterns of the aerobic bacterial flora associated with pond water, sediments, gills, and intestines of healthy African catfish, Clarias gariepinus, cultured in Saudi Arabia. Counts of viable bacteria ranged from 7.9 ± 4.4 103 to 4.3 ± 5.7 104 colony forming units (cfu)/mL in water; 1.3 ± 2.7 108 to 7.4 ± 4.6 109 cfu/g in sediments; 8.7 ± 1.8 106 to 6.6 ± 5.8 107 cfu/g in gill filaments; and 8.8 ± 6.2 108 to 4.3 ± 2.8 1010 cfu/g in intestines. The bacterial flora was predominantly comprised of gram-negative rods, accounting for 75% of the total isolated strains. Altogether, 11 bacterial species of 8 genera were identified: Aeromonas hydrophila, Shewanella putrefaciens, Vibrio cholerae, Staphylococcus sp., Corynebacterium urealyticum, and Vibrio vulnificus were the most common with the first three dominating (prevalence > 14%) in every population studied.  相似文献   

7.
The primary aim of the present study was to evaluate the population level of adherent (autochthonous) aerobic and facultative anaerobic bacteria in the hindgut of healthy Arctic charr (Salvelinus alpinus L.) fed dextrin or inulin. This was assessed by the dilution plate technique, and visualized using both transmission and scanning electron microscopy. A population level of 4.8 × 105 adherent bacteria per gram wet mass was found in the hindgut of fish fed a casein‐based diet supplemented with 15% dextrin. However, substituting dextrin with 15% inulin reduced the bacterial population level in the hindgut (3.56 × 104). A total of 217 bacterial isolates were identified by key phenotypical and biochemical characteristics. In addition, 22 strains were also identified by partial sequencing of the 16S rRNA gene. The composition of bacteria colonizing the hindgut of Arctic charr fed dextrin was dominated by the genera Staphylococcus, Pseudomonas, Micrococcus, Psychrobacter glacincola and Streptococcus. However, bacteria colonizing the hindgut of fish fed inulin were dominated by Gram‐positive bacteria of the genera Staphylococcus, Streptococcus, Carnobacterium and Bacillus. While Carnobacterium divergens‐like strains were isolated from charr fed dextrin, Carnobacterium maltaromicus‐like strains were isolated from the hindgut of fish fed inulin. Electron microscopical analysis of hindgut regions confirmed traditional culture‐based microbial analysis as fewer bacterial cells were observed between microvilli and associated with the surfaces of enterocytes of fish fed inulin rather than dextrin.  相似文献   

8.
The objective of this study was to evaluate the probiotic properties of lactic acid bacteria (LAB) strains isolated from digestive tract of white shrimp Litopenaeus vannamei. Eighteen LAB colonies were isolated and one bacterium was found capable of producing three extracellular enzymes (protease, cellulose and lipase) simultaneously and exhibited antagonistic activity against shrimp pathogens (Vibrio vulnificus, V. rotiferianus and V. campbellii). The putative probiotic strain AS13 was identified as Lactobacillus pentosus based on 16S rRNA sequencing. The L. vannamei were fed diet containing 0 (control), 106, 107 and 108 CFU g?1 bacterial cells of AS13 for 28 days. The results showed that supplementation of L. pentosus significantly improved the growth performance and feed utilization in the treated groups over the control. Similarly, digestive enzyme activities were elevated in the intestines of treated groups. Moreover, feeding of supplemented diets containing AS13 significantly reduced the mortality rate caused by pathogenic Vibrio species (V. vulnificus, V. rotiferianus and V. campbellii). Our results indicated L. pentosus AS13 addition at 107 CFU g?1 can effectively enhance the growth performance, feed utilization, digestive enzymes and disease resistance of L. vannamei in the laboratory condition.  相似文献   

9.
Information about bacterial community structure and functioning in fish farming ponds remains scarce, mainly due to methodological difficulties in counting and identifying uncultured bacteria. The main objective of this study was to evaluate the degree of similarity between the bacterial community of the digestive tract of tilapia (Oreochromis niloticus) juveniles and that of the test pond's water and sediment, using the Fluorescent In Situ Hybridization (FISH) technique. Samples of water, sediment and gut content of 30 tilapia juveniles from a single nursery ground were collected in January 2010. Potentially probiotic and pathogenic bacteria of the species Bacillus, Lactobacillus brevis, Lactobacillus collinoides, Lactobacillus coryniformis, Lactobacillus farciminis, Vibrio and Pseudomonas fluorescens were found in different samples using specific fluorescent probes. The similarity between bacterial community environments and gastrointestinal tracts was determined using the Morisita‐Horn index. The fish guts presented higher abundances of Pseudomonas fluorescens, Bacillus, Lactobacillus brevis and Lactobacillus collinoides. The bacterial community composition of tilapia gastrointestinal tract was more similar to the water than the sediment of the pond. The results of this study showed that the FISH technique can be easily used for monitoring of probiotics and pathogen detection in aquaculture systems.  相似文献   

10.
ABSTRACT

Quantitative and qualitative estimation of bacterial flora present in pond water, sediments, gills, and intestine of healthy common carp Cyprinus carpio cultured in Saudi Arabia were performed and identified to species level where possible. Mean total viable bacterial counts in pond water ranged from 1.2?±?2.9?×?104 to 2.5?±?3.5?×?105 cfu/mL; in sediments, 9.3?±?2.1?×?107 to 2.7?±?3.5?×?109 cfu/g; in gills filaments, 4.3?±?2.9?×?106 to 1.6?±?3.9?×?107 cfu/g; and in intestine, 8.7?±?4.1?×?109 to 5.4?±?3.2?×?1010 cfu/g. Gram-negative rod-shaped bacteria dominated (76%) the populations. In total, 12 bacterial genera and 15 species were identified. Pond water and sediment bacteria had the reflection on bacterial composition of gills and intestine of carp. Intestinal bacteria showed more diversification in contrast to gill bacteria. Aeromonas hydrophila, Shewanella putrefaciens, Vibrio cholerae, Corynebacterium urealyticum, Vibrio vulnificus, Vibrio sp., and Staphylococcus sp. were the common bacteria in all the populations. In pond water and carp intestine, A. hydrophila, S. putrefaciens, V. cholerae, and C. urealyticum were the most dominant bacteria (prevalence ≥ 10%) where pond sediments and the carp gills experienced with more one dominant bacterium V. vulnificus. Only the A. hydrophila covered one fourth (25%) of the total bacterial populations.  相似文献   

11.
The objective of this study was to evaluate the effects of liquid and wood smoking with a potassium lactate (PL) and acetate (PA) combination on the quality and inhibition of L. monocytogenes growth in ready-to-eat (RTE) smoked catfish fillets. Catfish fillets were tumbled with PL and PA, and treated with no smoke (NS), wood smoke (WS), liquid smoke 1 (LS1), and liquid smoke 2 (LS2). Wood smoke with antimicrobials (WSWA) showed greater inhibition (p < 0.05) of L. monocytogenes growth than other treatments with the exception of the LS1 treatment with antimicrobials. Consumers preferred (p < 0.05) smoked catfish fillets treated with WS to LS1 with respect to appearance, odor, flavor, texture, and overall acceptability. In conclusion, the use of PL and PA did not have a negative impact on the quality and sensory properties of smoked catfish fillets but had a synergistic effect with wood smoke constituents that inhibited the growth of L. monocytogenes.  相似文献   

12.
Peptones were obtained from cod stomachs as a by-product during enzyme production. Minced cod stomachs were autolyzed after acidification with either formic or phosphoric acid, and low molecular weight (< 10 kDa) peptones were recovered. When formic acid was used, an acid peptone was obtained, whereas phosphoric acid was removed from the peptone after calcium precipitation. The peptones were compared with Proteose Peptone (Difco, Detroit, MI, USA) as nitrogen sources in growth media for three marine bacteria. Two fish pathogens—Vibrio anguillarum and Aeromonas salmonicida—grew equally well or better on the cod stomach peptones, whereas a probiotic lactic acid bacteria (Carnobacterium divergens), isolated from salmon intestines, grew much better on the cod stomach peptones than on Proteose Peptone.  相似文献   

13.
实验根据GenBank公布的细菌全基因组数据,采用比较基因组学分析创伤弧菌与其它细菌基因组间的差异,筛选出34个潜在的创伤弧菌物种特异性检测靶标基因,其中VV1_2692、VV2_0075和VV2_0939这3个基因已有功能注释.常规PCR扩增结果显示这3个基因均具有良好的特异性和灵敏度.进而以这3个基因和传统靶基因vvhA作为检测靶标,采用常规PCR技术检测来自杭州市农贸市场的137份海产品中创伤弧菌,发现VV2_0075、VV2_0939和vvhA基因的检测结果与传统生化鉴定方法一致,表明新发掘的VV2_0075和VV2_0939基因在对海产品中创伤弧菌检测时具有很好的稳定性和很强的抗干扰能力.在137份海产品中创伤弧菌的检出率为28.5％,其中牡蛎的检出率最高(68％),表明杭州市农贸市场售卖的海产品,尤其是牡蛎中的创伤弧菌污染现状严重,应加强对杭州市海产品中创伤弧菌污染状况的监测.  相似文献   

14.
Four alkaloids (Sanguinarine, 6‐Methoxyl‐dihydro‐chelerythrine, Cryptopine and β‐Allocryptopine) were isolated from aerial parts of Macleaya microcarpa (Maxim) Fedde using bioassay‐guided isolation method, and the inhibitory activity of ethanolic extract, various fractions and these four alkaloids against four fish pathogenic bacteria (Aeromonas hydrophila, Aeromonas salmonicida, Vibrio anguillarum and Vibrio harveyi) was assessed in vitro using the agar dilution method and the microdilution assay method respectively. A. hydrophila was the most sensitive strain to all the tested compounds. Minimum inhibitory concentration (MIC) values were lower for sanguinarine against all tested Gram‐negative strains than other three alkaloids, with MIC values of 12.5 mg L?1 for A. hydrophila and 50 mg L?1 to other pathogenic bacteria. Followed by 6‐methoxyl‐dihydro‐chelerythrine, which showed considerable antibacterial activity with MIC values of 80 mg L?1 for A. hydrophila, 100 mg L?1 for V. harveyi, and 125 mg L?1 for both V. anguillarum and A. salmonicida. Cryptopine and β‐allocryptopine revealed similar inhibitory activity with MIC values of 100 mg L?1 for A. hydrophila and 200 mg L?1 for other three bacterial species. These finding provided evidence that extract, as well as isolated compounds from M. microcarpa might be potential sources novel antibacterial agents for the treatment of fish infectious diseases.  相似文献   

15.

Bacteriophage isolated from the semi-intensive culture of Pacific white leg shrimp Litopenaeus vannamei infects the luminous bacteria Vibrio harveyi. Lytic activity and lytic spectrum results revealed that the isolated phage had strong lytic activity in V. harveyi, V. parahaemolyticus, and V. vulnificus. Biofilm inhibition activity was performed against different pathogenic vibrios on high-density polyethylene (HDPE) template and the result revealed that the phage effectively inhibited the biofilm formation in V. harveyi. Spectrophotometric assay performed for lytic activity of the isolated phage in V. harveyi liquid culture showed that the phage significantly decreased the V. harveyi cell densities at different time intervals (P?<?0.05). To study the stability of phage at different temperature and pH revealed that the phage withstands the temperature ranged between 40 and 70 °C and the pH of 4 and 9 at a significant level (P?<?0.001). One-step growth curve depicted that the burst size gradually increased to a significant level and reached the maximum of 90% at 180 min (P?<?0.05). This study concluded that the isolated phage had specific activity against pathogenic V. harveyi infections.

  相似文献   

16.
为了解仿刺参体腔液的抗菌谱以及不同二价金属离子对仿刺参体腔液抗菌活性的影响,实验采用生长曲线测定法分别测定了仿刺参体腔细胞破碎液上清和体腔液上清对哈维氏弧菌、灿烂弧菌、希瓦氏菌、假交替单胞菌、金黄色葡萄球菌、溶壁微球菌、停乳链球菌、拟诺卡式菌生长的影响,并通过该法以溶壁微球菌为受试菌测定了海洋环境中常见的Fe2+、Ca2+、Cd2+、Mg2+、Mn2+、Zn2+对仿刺参体腔液上清抗菌活性的影响。结果显示,仿刺参体腔细胞破碎液上清对受试的8株细菌的生长均无抑制作用,体腔液上清对溶壁微球菌的生长有明显的抑制作用,而对其他7株受试菌的生长无明显影响;Mn2+和Zn2+可明显增强体腔液上清对溶壁微球菌的生长抑制作用,而Fe2+、Ca2+、Cd2+、Mg2+对体腔液上清的抗菌活性无明显影响。研究表明,仿刺参体腔液在体外状态下只具有窄谱抗菌活性,与抗菌相关的免疫因子主要存在于体腔液上清中;体腔液中的抗菌免疫因子对海洋环境中的常见二价金属离子有一定的适应性,而且适当浓度的Mn2+和Zn2+可能具有促进仿刺参抗菌应答能力的作用。  相似文献   

17.
The impacts of fermentation process with acid and lactic acid bacteria strains (Lactobacillus plantarum, Lactobacillus brevis, Pediococcus acidilactici, Enterococcus gallinarum, and Streptococcus spp.) on the biogenic amine formation of wet and spray-dried fish silage obtained from whole gibel carp (Carassius gibelio, freshwater discard), whole ponyfish (Equulites klunzingeri, seawater discard), and processing by-products of seabass (Dicentrarchus labrax) were investigated. The results showed that among biogenic amines, cadaverine, putrescine, spermidine, spermine, serotonin, dopamine, and agmatine were predominant in all groups. Significant differences (p < 0.05) in biogenic amine concentrations of wet and spray-dried fish silage were observed. Raw fish and wet silages contained histamine level lower than the allowable limit of 50mg/kg, indicating the use of raw fish material with low microbial counts. In addition, no histamine was detected in spray-dried fish silage, except for seabass by-products with a trace quantity of histamine (<0.04mg/100g). The starter culture used for silage preparation did not effectively retard formation of biogenic amines compared to acid silage. It can be concluded that there is potential use of fermented fish silage as a protein source and possibly as a probiotic ingredient for animal feed in both wet and dry form.  相似文献   

18.
ABSTRACT

Desalted cod spoilage isolates were tested in culture broth for growth inhibition by citric acid and potassium sorbate. Preservative effect was also evaluated in refrigeratedcod juice and desalted cod spiked with Shewanella putrefaciens and Pseudomonas fluorescens orputida. Combination of 0.15% citric acid and 0.1% potassium sorbate inhibited growth of approximately 60% of isolates, including the former two strains. Total inhibition was observed for S. putrefaciens and partial inhibition was noticed for P. fluorescens or putida, in both treated juice and desalted cod. Preservatives delayed growth of halotolerant bacteria in cod. Citric acid plus potassium sorbate addition lowered the pH to extend desalted cod shelf life.  相似文献   

19.
Five cultures of microalgae (Chlorella minutissima, Tetraselmis chui, Nannochloropsis sp., Arthrospira platensis and Isochrysis sp.) with no culturable bacteria were tested for their ability to inhibit the growth of six Vibrio bacterial strains (V. parahaemolyticus, V. anguillarum, V. splendidus, V. scophthalmi, V. alginolyticus and V. lentus). The influence of light on the antibacterial activity of the microalgae was investigated. All microalgae cultures inhibited the growth of bacteria compared with the control treatments (P < 0.05), and their antibacterial activity was not influenced by the presence or absence of light. In the control groups, the numbers of bacteria increased exponentially during the experimental period in the absence of microalgae cells demonstrating that the bacterial cells were able to utilize the growth medium of microalgae cultures. The present results may explain the low levels or absence of Vibrio strains in microalgae cultures, and the positive effect of addition of microalgae in rearing of fish larvae, and implicate the production of antibacterial compounds by microalgae cells.  相似文献   

20.
Doctor fish (Garra rufa, Heckel, 1843) are increasingly used for cosmetic treatment raising particular concerns regarding the potential transmission of infections to clients. Investigations of microbial causes undertaken in two outbreaks of mortality among G. rufa used for cosmetic treatment revealed the presence of multiple bacteria, including both fish and human pathogens such as Aeromonas veronii, A. hydrophila, Vibrio cholerae, Shewanella putrefaciens, Mycobacterium marinum and M. goodii. This range of bacteria indicates an intense microbial proliferation involving multiple pathogens, most likely induced by the poor health condition of the fish. Most of the detected pathogens are well‐known agents of zoonosis. Indeed, M. goodii is an emerging nosocomial human pathogen that has never been detected in fish to date, nor in other animals. This first detection of M. goodii associated with fish infection points out a new zoonotic potential for this pathogen. These findings point out that handling, poor environmental conditions and the presence of fish pathogens, that can compromise the immune system of fish, can result in a mixed microbial proliferation and increase the spread of waterborne bacteria, including zoonosis agents. Accordingly, the microbiological surveillance of fish used for cosmetic treatment is extremely important, particularly in association with mortality outbreaks.  相似文献   

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