جستجوی مقالات مرتبط با کلیدواژه « باکتری » در نشریات گروه « شیلات »

In recent years, the use of bacteria is growing to research into the reduction of chemical pollutants. However, no information has been reported on the protective effect of these bacteria on living organisms, including Artemia. Thus, the effect of probiotic Pediococcus acidilactici on reduction of diazinon pesticide toxicity in Artemia franciscana was investigated. In the first, the lethal dose of diazinon toxin was determined on Artemia nauplii. Then five treatments of different probiotic concentrations (3.75×106, 7.5×106, 11.25×106 and 15×106 CFUmL-1) were used to evaluate the reducing effect of the diazinon in the culture media of Artemia nauplii. For to this, five concentrations of 20 to 60 mgL-1 were used to determine the 24h-LC50 toxicant concentration in A. francicana, which at the lowest concentration, the mortality rate was more than 50% over a 24-hour period. In the second experiment, the concentrations of 12 to 18 mgL-1 diazinon were used. Based on the results, the 24h-LC50 lethal concentration was calculated as 12 mgL-1. The amount of diazinon in different concentrations of probiotic bacteria was calculated by gas chromatography. Toxin removal was observed at 82% at the lowest bacterial concentration (7.5×106 CFUmL-1) and 95% at the highest density (22.5×106 CFUmL-1). Simultaneous addition of bacteria and diazinon significantly reduced Artemia mortality compared to the control treatment (p<0.05). However, in different probiotic treatments, bacterial concentrations showed no significant difference in Atremia mortality (p>0.05). The results of this study indicated that the probiotic P. acidilactici has a significant effect on reducing the toxicity of diazinon as an organophosphorus toxin. The results also showed that the simultaneous presence of diazinon and bacteria on the rate of Artemia mortality indicates the elimination and inactivation of the toxin by the bacteria.

Aquaculture diseases and its damages have affected the aquaculture industry around the world. Tilapia is newly introduced to the aquaculture industry of Iran. While tilapia is a tolerant fish, there are reports of infectious diseases, and it is essential to plan for their prevention and control. Health surveys of tilapia breeding indoor systems were carried out at the National Research Center of Saline Water Aquatics (Bafq, Yazd) in 2012-2014. Parasitic, bacterial, fungal and viral studies of eggs, fries, brooders and cultured fish were performed by observing abnormal movement, nutrition and symptoms of the fish as well as unusual mortality. Infection with parasitic agents Gyrodactylus sp. and Dactylogyrus sp., bacterial agents Streoptococcus sp. and Edwardsiella sp. and fungi of Penicillium sp. and Aspergillus sp. determined. The samples were negative for Herpesvirus, EHNV and BIV viruses. Although pathogens and disease factors have been rarely observed in the Nile tilapia Oreochromis niloticus and red hybrid tilapia, monitoring and enforcement of health guidelines is particularly important in preventing disease.

Considering the high importance of food poisoning bacteria in terms of public health threats and economic damages, this research aimed at evaluating food poisoning bacteria in some commercially important fish species collected from markets in Mazandaran, Iran.

For this purpose, 200 frozen fish belonging to 4 species were purchased from the stores and transferred to the laboratory. Samples were tested for total counting of aerobic bacteria, Escherichia coli count, Staphylococcus aureus count, Vibrio parahaemolyticus and detection of Salmonella according to Iranian national standard methods.

In the studied samples, Salmonella, and Vibrio parahaemolyticus were not observed. Comparing the results with the Iranian national standards, the total number of aerobic bacteria and Staphylococcus aureus in all samples was in normal range. The number of E. coli in 14% of samples of Rain bow trout, 20% of Clupeonella Cultriventris, 20% of Hypophthalmichthys molitrix and 10% of Scomberomorus commerson samples was higher than the standard range, due to the importance of pathogenicity of different strains of E. coli in humans, microbial control of the packed fish is very important.

The results of microbial investigations of frozen raw fish collected from stores in different cities of Mazandaran province can be defined satisfactorily, since the majority of samples conform to reference standards.

Goldfish rearing is common in most countries of the world. In this study, 150 specimens of Goldfish were taken from four fish farms (12 pools) seasonally and selectively, and transferred alive in the bacteriological laboratory of Inland Waters Aquaculture Research Center. The bacteria were isolated from professional test and biochemical methods. The results showed that Goldfish and pool water bacteria isolations were included Enterobacteriaceae, Pseudomonas sp., Aeromonas sp., Sterptococcus sp., Vibrio sp., Mycobacterium sp. In different seasons of the year, the highest and lowest abundance of bacteria in Goldfish, respectively, belonged to the genus Pseudomonas spp. (33/6%) and Streptococcus spp. (7/3%).

In general, the relationship between zooplankton and bacteria is important to increase the productivity of live food production. The present study was done with the objective to investigate the predominant bacteria in Daphnia pulex (Cladocera) and Apocyclops dengizicus (Copepoda) fed with manure (chicken and sheep manure at rates of 1:1), vegetables (Fenugreek + Thymus + Savory at rates of 1: 1: 1 weight ratio) and Oscillatoria africanum, the effect of culture medium on zooplankton density and medium BOD and COD. The results showed that different diets had a significant effect on the D. pulex and A. dengizicus density, bacterial populations and biochemical medium properties (BOD and COD). The dominant bacteria in the mediums enriched with manure and vegetables for D. pulex were Acinetobacter sp. and in the medium containing O. africanum, Aeromonas sp. was dominant. In the A. dengizicus cultivation medium enriched with manure, vegetables and O. africanum, the Neisseri sp., Enterobacteria sp. and Alcaligenes sp. were dominant, respectively. Maximum microbial population in medium was measured in D. pulex fed manure (11×104 cells/ml) and A. dengizicus fed with O. africanum (12×103 cells/ml). The highest density of D. pulex (289±11.9) and A. dengizicus (188±19.2) were calculated in the medium enriched with O. africanum, while the least density was counted when manure was used. BOD and COD showed maximum amount in D. pulex and A. dengizicus fed with vegetables (101 and 298 mg/l, respectively). The results showed that there was no significant correlation between D. pulex density and bacterial population, but there was a significant correlation between bacterial populations and A. dengizicus density. Also, there was a significant correlation between zooplankton density (D. pulex and A. dengizicus) and biochemical medium parameters (BOD and COD). In general, it can be concluded that in order to achieve the highest density of D. pulex and A. dengizicus, the use of culture media containing O. africanum has a higher efficiency. Also, zooplankton species and diet used during breeding period affect the type of bacteria and their population density.

Ornamental fish keeping and its propagation has been an important activity for many which provide not only aesthetic pleasure but also financial openings. Bacterial disease is the most common infectious problem of ornamental fishes, and most bacterial infections are caused by gram-negative organisms. The majority of bacterial fish pathogens are natural inhabitants of the aquatic environment, whether it be freshwater or marine. Extrinsic stressors, including shipping, crowding, poor water quality, and inadequate nutrition, may predispose an ornamental fish to bacterial disease. This article reviews the important bacterial pathogens of ornamental fish and reviews treatment and management options.

Probiotics are beneficial microorganisms of intestine with useful effects on growth and health of the animals by the colonization. In present study, effects of two different probiotic as Bacillus subtilis and Saccharomyces cerevisiae were investigated on growth parameters, survival, and body composition of A. franciscana. Also the resistance against pathogenic bacteria of Vibrio campbellii was studied with the animals being exposed to 1× 105CFU per mL of bacteria. The experiment was designed in 4 treatments: treatment one as a control (no probiotic), treatment two (food bacteria), treatment three (food yeast) and treatment four (food with equal amounts of yeast and bacteria). The survival and growth rate of the animals were measured on day 8 and 15 of culture period. At the end of the experiment (day 15), the Artemia was challenged with pathogenic V. campbellii in which survival of the animals were calculated finally. Based on the results, the maximum body size significantly was showed in treatment two that had significant difference with control (P 0.05). After 24, 48 and 72 hours of exposure of pathogenic bacteria, the highest and lowest survival rate were found in group four and group control (no probiotic), respectively (P

The outbreak of diseases is a limiting factor in fish farms. A large number of plants are being used in traditional medicine for the treatment and control of diseases. One of such plants is ginger (Zingiber officinale). In this study antimicrobial effects of alcoholic extracts of ginger on six important positive and negative gram bacteria including Vibrio alginolyticus, Vibrio parahemolyticus, Micrococcus luteus, Staphylococcus epidermicus, Bacillus cereus, Stereptococcus zoo epidermicus were analyzed. Extraction was conducted on rhizomes of Ginger using 80% ethanol in laboratory. In order to assess antimicrobial effects of the ginger extract on the studied bacterial species, diffusion test on agar media using disk method on studied bacteria was conducted. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were determined by serial dilution assay using Liquid culture in 96 wells microplates. Results indicated that ginger alcoholic extracts have inhibitory effects on the bacterial growth and is lethal for all bacterial strains. Also ginger alcoholic extract has the most and the least growth inhibitory and lethal affects on Vibrio alginolyticus and Vibrio parahemolyticus, respectively.

In this study, the effect of gelatin coating enriched with cinnamon oil for fresh fillet of rainbow trout on microbial were studied, chemical and sensory characteristics during storage at refrigerator condition. Fish fillet were treated in gelatin solution (4 percent) containing cinnamon oil and were stored in refrigerator. Total viable count was acceptable (7 log CFU/g) for coated fillets with gelatin coating containing cinnamon essential oil on day 15, but the control fillets also those that were covered with gelatin receipt to 7.88 and 7.44, respectively. In the tenth day. Psychrotrophic count values for the control and gelatin coated fillets significantly were increased more than other treatment. Total volatile bases nitrogen and Thiobarbituric acid values in gelatin with cinnamon coated fillet were less than other treatment. In general, results suggest successful inhibition microbial growth in refrigerated rainbow trout fillet is possible with gelatin incorporated cinnamon coating, as together they kept the sensory characteristics within acceptable limits throughout storage. Gelatin coating together with cinnamon oil provides a type of active coating that can be utilized as a safe preservative for fish under refrigerated storage.

Bacterial and fungal microflora of Litopenaeus vannamei cultured in Choibdeh, Abadan was studied. For this purpose, PLs before and after stocking and those shrimps persisting on food tray from June to August, 2006 were taken randomly. Live samples transferred to microbiology laboratory of South Aquaculture Research Center, Ahwaz. Special culture media (e.g. Tryptic Soy Agar + 1.5-2% Nacl & Sabouraud Dextrose Agar + 1.5-2% Nacl) were used for bacterial and fungal culture. We isolated 10 bacterial species of which Vibrio alginolyticus (36.92%) had high abundance among bacterial species. We also isolated and identified three fungal species including Aspergillus niger (66.66%) A. fumigatus (16.66%) and Fusarium sp. (16.66%). A. niger was predominant among fungal species. All bacterial and fungal species that were identified were opportunistic.

The health status and diseases of Penaeus indicus in Sista-o-Baluchistan culture ponds of Guater Site were assessed during the year 2005. Over the shrimp culture period, two ponds were selected from two farms, and 19 shrimp specimens were caught randomly each month from each pond. The specimens were immediately transferred to lab for further investigation. After recording abnormal signs including colour change of cuticle and gills, presence of white or black spots on the body, the specimens were studied for bacterial, fungal and parasitic infections. Bacterial infections included Citobacter, Pseudomonas, Aeromonas, Actinobacter, Proteus, Vibrio alginolyticus, V. harveyi, V. parahaemolyticus, V. spelendidus and Vibrio sp. Fungal infections of the cultured P. indicus included Fuzarium spp., Mucor, Cladosporium, Aspergillus spp., Penicllinium spp., sterilized hyphae and yeast. The parasites found included Zoothamnium, Epistylis, andVorticella. Since the second month of shrimp culture onwa.....

Tashk Lake is located in the protected zone of the Bakhtegan Lake in the Fars Province and is a shelter for wildlife. This place is very important environmentally and ecologically. Among entering pollutants to this lake via rivers and side villages, polycyclic aromatic hydrocarbons (PAHs) compounds are noteworthy which are very harmful to humans and others creatures alike. We used naphthalene and anthracene as the only source of carbon to isolate PAHs degrading bacteria from three predefined stations. We found Pseudomonas sp. as the only PAHs degrading bacterium in the water and sediments of the lake. At the station 1 (Dehzir), the mean isolated bacteria acting on naphthalene and anthrecene were 27 and 23 in each ml of water and 57 and 47 in each gram of sediments, respectively. At the station 2 (Tashk), the mean isolated bacteria were 67 and 57 in each ml of water and 120 and 113 in each gram of the sediments which acted on the two carbon sources respectively. At the station 3(Gomban), the figures were 127 and 113 for water and 163 and 147 for the sediments respectively. We found meaningful differences in the mean number of degrading bacteria in the water and sediments of the three stations (P<0.05). The salt concentration for Pseudomonas sp. optimum growth and PAHs degradation was found to be around 6% with and increasing rate of degradation over time.

We Collected 75 samples from fish meal factories in Guilan Province (codes: 1,2,3,4,5,6,7) based on two times per month during June to December 2001. Standard reference are used in bacterial and fungous identification. The isolated bacteria are E. coli Proteus spp., Citrobacter spp., Shigella spp., Enterobacter Aerogenes Salmonella spp., Klebsiella spp., Hafina Alvei Yersinia Enterocolitica, Edwardsiella spp., Staphylococcus spp., Bacillus spp., Pseudomonas spp., Clostridium spp., Aeromonas Hydrophila Streptococcus spp. The highest and lowest bacterial contamination observed in E. coli and Hafina Alvei respectively. The most important isolated fungi were Aspergillus spp., Penicillium spp., Yeasts Rhizopus spp. The maximum and minimum fungi decay in samples were Penicillium spp., and Rhizopus respectively. The most and the least microbial spoilage have been seen in factories 1 and 2 respectively.

Following a mortality of up to 40% of cultured Grass Carp (Ctenopharyngodon idella) in fish farms of Khouzestan province when water temperature was up to 20 C, samples were taken and examined for etiological clues. We observed that fish gills were coated with a gray-white mucus layer, fin was eroded and wounds were present in peduncle of the affected samples. Bacteriological studies on the samples of gills and eroded and wounded peduncle skin using Cytophaga selective medium, resulted in isolation of filamentous gram negative bacteria chemically similar to Flavobacterium columnare.
Histological observations showed the affected fish carrying symptoms including congestion, hemorrhagia, edema in base membrane, hyperplasia of chondrocyte and secondary lamellae cells, fusion of lamellae, necrosis and peeling of secondary lamellae and also presence of filamentous bacteria in gill tissue sections. Necrosis of skin layers and expansion of ulcer to underlying muscles, degeneration of muscle cells and necrosis of muscle bundles were seen in peduncle muscles. We did not find this bacterium in internal organs. We conclude that the isolation of the bacterium and observation of histo-pathological changes suggest the organisms may be considered as a primary or secondary factor in occurrence of the disease.

Fish sauce is a popular fermented product used in south Asian countries which is made from different species of small fishes. In this research it was attempted to produce fish sauce from kilka fishes of the Caspian Sea. The kilka sauce was made from three different preparations of kilka, such as whole kilka, cooked whole kilka and dressed kilka. Each of these preparations was fermented in four different ways, such as traditional, enzymatic, microbial and mixture of enzyme and microorganisms. The results of this study showed that times of fermentation for traditional, enzymatic, microbial and mixture of enzyme and microbe method were 6, 1,3 and 1 months, respectively. The least and the most rate of fermentation were recognized for dressed kilka and cooked whole kilka, respectively. Microbial, biochemical and organoleptic properties of kilka fish sauce were investigated. The total bacterial count was 2.1 to 6.15 log cfu/ml, total volatile nitrogen (TVN) in samples was 250 mg/100g and protein content of kilka sauce was between 10-13 percent. The score of the taste panel for flavour, odour and colour was between 3 to 5, which means this product can be acceptable to the consumer.

This project was conducted to determine the effect of Pseudomonas fluorescence bacteria on increasing the growth rates of some species of algae namely Chaetoceros Sp. , Skeletonema sp. , Tetraselmis sp. , Chlorella sp.  
In this order, the mentioned bacteria were extracted by separator and Zobell 16E media from prawn broodstock ponds, then purified and mass cultured. The algae selected mass, were cultured in Conway media and then these bacteria were investigated at the blooming phase in the several experiments of various treatments in combined culture method. The results revealed that the mentioned bacteria could apply as a partial substitution body of aglae media and it could be used as a new media in various percentages. The results indicated, the very positive effect of bacteria on cultured algae. Therefore, Pseudomonas fluorescense can be used in algae cultured in 50-150 mglit density as a new method for algae culture. This bacterium Could be a new media for Chaetoceros sp. , and Tetraselmis sp. , but for Skeletonema sp. , other percentages of media should be used.