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Auswahl der wissenschaftlichen Literatur zum Thema „Environmental aeromonads“
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Zeitschriftenartikel zum Thema "Environmental aeromonads"
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Huddleston, Jennifer R., John C. Zak und Randall M. Jeter. „Sampling bias created by ampicillin in isolation media forAeromonas“. Canadian Journal of Microbiology 53, Nr. 1 (01.01.2007): 39–44. http://dx.doi.org/10.1139/w06-103.
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Members of the bacterial genus Aeromonas are widely isolated from aquatic environments and studied in part for their ability to act as opportunistic pathogens in a variety of animals. All aeromonads, with the exception of Aeromonas trota, are generally thought to be resistant to ampicillin, so the antibiotic is frequently added to isolation medium as a selective agent. In this study, 282 aeromonads from environmental sources were isolated on a medium without ampicillin and their resistance to ampicillin determined. Of the 104 of these isolates that were judged to be independent (nonredundant), 18 (17.3%) were susceptible to ampicillin. A chi-square analysis was performed to determine the impact of ampicillin use on enumerating Aeromonas species from environmental samples. Our results indicate that, when ampicillin is used as a selective agent, a significant portion of the aeromonad population in at least some environ ments can be omitted from isolation.Key words: Aeromonas, ampicillin, selective media.
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Ashbolt, N. J., A. Ball, M. Dorsch, C. Turner, P. Cox, A. Chapman und S. M. Kirov. „The identification and human health significance of environmental aeromonads“. Water Science and Technology 31, Nr. 5-6 (01.03.1995): 263–69. http://dx.doi.org/10.2166/wst.1995.0621.
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Aeromonads readily grow in waters, particularly if nutrified, to concentrations in excess of total coliforms. Strains of aeromonads can cause gastroenteritis and tissue necrosis. Several suspected virulence factors, such as haemolysins, cytotoxins and enterotoxins may be involved in their pathogenesis. Amongst the thirteen recognised hybridisation groups of Aeromonas, only five species were identified by eight phenotypic characteristics from 339 strains isolated from marine, fresh river or storm waters or from tertiary and sewage/primary effluents. The majority of strains (50%) showed atypical phenotypes, and 24% of 208 randomly selected strains were not identified as aeromonads with a genus specific 16S rDNA-targeted PCR. Most discrepancies occurred with A. schubertii phenotypes, none of which were identified as aeromonads by PCR. Marine waters contained the largest proportion of atypical phenotypes (45/67) of which 60%, compared to <20% for other water sources, were not identified as aeromonads by PCR. A. hydrophila was generally the predominant species identified (93/339), although A. caviae was more prevalent in tertiary treated sewage effluents. Freshwaters contained the largest proportion of aeromonads with haemolysin and/or enterotoxin activity, whereas cytotoxin activity was more prevalent from stormwater isolates. Freshwater strains of A. veronii biotype sobria and A. hydrophila appeared to be the most toxigenic. Furthermore, river sites downstream of sewage effluent release contained more aeromonads than sites immediately upstream of the discharge. Hence, there was a clear positive correlation between freshwater eutrophication and the presence of potentially virulent aeromonads, the majority of which were A. hydrophila and A. veronii which can most rapidly and accurately be identified by PCR.
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Bomo, A. M., M. V. Storey und N. J. Ashbolt. „Detection, integration and persistence of aeromonads in water distribution pipe biofilms“. Journal of Water and Health 2, Nr. 2 (01.06.2004): 83–96. http://dx.doi.org/10.2166/wh.2004.0008.
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The occurrence of Aeromonas spp. within biofilms formed on stainless steel (SS), unplasticized polyvinyl chloride (uPVC) and glass (GL) substrata was investigated in modified Robbins Devices (MRD) in potable (MRD-p) and recycled (MRD-r) water systems, a Biofilm Reactor™ (BR) and a laboratory-scale pipe loop (PL) receiving simulated recycled wastewater. No aeromonads were isolated from the MRD-p whereas 3–10% of SS and uPVC coupons (mean 3.85 CFU cm−2 and 12.8 CFU cm−2, respectively) were aeromonad-positive in the MRD-r. Aeromonads were isolated from six SS coupons (67%) (mean 63.4 CFU cm−2) and nine uPVC coupons (100%) (mean 6.50×102 CFU cm−2) in the BR™ fed with recycled water and from all coupons (100%) in the simulated recycled water system (PL). Mean numbers of aeromonads on GL and SS coupons were 5.83×102 CFU cm−2 and 8.73×102 CFU cm−2, respectively. No isolate was of known human health significance (i.e. Aeromonas caviae, A. hydrophila or A. veronii), though they were confirmed as Aeromonas spp. by PCR and fluorescence in situ hybridization (FISH). Challenging the PL biofilms with a slug dose of A. hydrophila (ATCC 14715) showed that biofilm in the PL accumulated in the order of 103–104A. hydrophila cm−2, the number of which decreased over time, though could not be explained in terms of conventional 1st order decay kinetics. A sub-population of FISH-positive A. hydrophila became established within the biofilm, thereby demonstrating their ability to incorporate and persist in biofilms formed within distribution pipe systems. A similar observation was not made for culturable aeromonads, though the exact human health significance of this remains unknown. These findings, however, further question the adequacy of culture-based techniques and their often anomalous discrepancy with direct techniques for the enumeration of bacterial pathogens in environmental samples.
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Egorov, Andrey I., Jennifer M. Birkenhauer Best, Christopher P. Frebis und Michella S. Karapondo. „Occurrence of Aeromonas spp. in a random sample of drinking water distribution systems in the USA“. Journal of Water and Health 9, Nr. 4 (20.06.2011): 785–98. http://dx.doi.org/10.2166/wh.2011.169.
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Aeromonads are aquatic bacteria found in drinking water supplies worldwide. Some species, such as Aeromonas hydrophila, can cause disease in humans. For this survey, 293 United States public water systems were selected using random sampling, stratified by water source and system type. Water samples were collected during one year from three sites (six samples per site) in each system. Temperature, pH, turbidity, total and free chlorine were measured using standard methods. Aeromonads were detected in 130 of 5,042 valid samples (2.6%) from 42 (14.3%) systems using the ampicillin-dextrin agar with vancomycin culture method with oxidase, trehalose and indole confirmation tests. Concentrations of aeromonads in positive samples were 0.2 to 880 (median 1.6) colony-forming units (CFU) per 100 mL. Adjusted odds ratios of Aeromonas detection were 1.6 (95% confidence limits 1.0, 2.5) during the summer season, 3.3 (1.8, 6.2) for turbidity above 0.5 nephelometric units and 9.1 (3.5, 24) at 0 mg/L compared with 0.25 mg/L total chlorine. Geographic region, system size and type of water source were not significant predictors of Aeromonas detection in multivariate regression analysis. The results of this survey demonstrate the importance of maintaining adequate residual chlorine and low turbidity for preventing drinking water contamination with aeromonads.
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Khan, Izhar U. H., Alyssa Loughborough und Thomas A. Edge. „DNA-based real-time detection and quantification of aeromonads from fresh water beaches on Lake Ontario“. Journal of Water and Health 7, Nr. 2 (01.02.2009): 312–23. http://dx.doi.org/10.2166/wh.2009.041.
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The present study was designed to develop a novel, rapid, direct DNA-based protocol to enumerate aeromonads in recreational waters. An Aeromonas genus-specific real-time quantitative polymerase chain reaction (Q-PCR) protocol was developed and optimized using newly designed genus-specific oligonucleotide primers derived from the gyrase B subunit (GyrB) gene. A standard curve was developed based on the PCR protocol with a minimum quantification limit of 10 cell equivalents ml−1 achieved using an autoclaved water sample from recreational water spiked with known quantities of an Aeromonas ATCC strain. The Q-PCR protocol was validated and applied to detect and quantify the total number of aeromonads in water samples collected from two fresh water beaches on Lake Ontario. The Q-PCR protocol revealed significantly higher numbers of aeromonads in all water samples than a culture-based assay at both beaches. Foreshore sand was found to serve as a reservoir of high concentrations of Aeromonas similar to this phenomenon noted for enteric bacteria like Eschershia coli. The new real-time Q-PCR protocol facilitated the rapid quantification of total numbers of Aeromonas cells present in recreational water samples in <3 hours without culturing.
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Albert, M. John, M. Ansaruzzaman, Kaisar A. Talukder, Ashok K. Chopra, Inger Kuhn, Motiur Rahman, A. S. G. Faruque, M. Sirajul Islam, R. Bradley Sack und Roland Mollby. „Prevalence of Enterotoxin Genes in Aeromonas spp. Isolated From Children with Diarrhea, Healthy Controls, and the Environment“. Journal of Clinical Microbiology 38, Nr. 10 (2000): 3785–90. http://dx.doi.org/10.1128/jcm.38.10.3785-3790.2000.
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Aeromonads are causative agents of a number of human infections. Even though aeromonads have been isolated from patients suffering from diarrhea, their etiological role in gastroenteritis is unclear. In spite of a number of virulence factors produced byAeromonas species, their association with diarrhea has not been clearly linked. Recently, we have characterized a heat-labile cytotonic enterotoxin (Alt), a heat-stable cytotonic enterotoxin (Ast), and a cytotoxic enterotoxin (Act) from a diarrheal isolate ofAeromonas hydrophila. Alt and Ast are novel enterotoxins which are not related to cholera toxin; Act is aerolysin related and has hemolytic, cytotoxic, and enterotoxic activities. We studied the distribution of the alt, ast, andact enterotoxin genes in 115 of 125 aeromonads isolated from 1,735 children with diarrhea, in all 27 aeromonads isolated from 830 control children (P = 7 × 10−4for comparison of rates of isolation of aeromonads from cases versus those from controls), and in 120 randomly selected aeromonads from different components of surface water in Bangladesh.Aeromonas isolates which were positive only for the presence of the alt gene had similar distributions in the three sources; the number of isolates positive only for the presence of the ast gene was significantly higher for the environmental samples than for samples from diarrheal children; and isolates positive only for the presence of the act gene were not found in any of the three sources. Importantly, the number of isolates positive for both the alt and ast genes was significantly higher for diarrheal children than for control children and the environment. Thus, this is the first study to indicate that the products of both the alt and ast genes may synergistically act to induce severe diarrhea. In 26 patients,Aeromonas spp. were isolated as the sole enteropathogen. Analysis of clinical data from 11 of these patients suggested that isolates positive for both the alt and astgenes were associated with watery diarrhea but that isolates positive only for the alt gene were associated with loose stools. Most of the isolates from the three sources could be classified into seven phenospecies and eight hybridization groups. For the first time,Aeromonas eucrenophila was isolated from two children, one with diarrhea and another without diarrhea.
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Tokajian, Sima, und Fuad Hashwa. „Phenotypic and genotypic identification of Aeromonas spp. isolated from a chlorinated intermittent water distribution system in Lebanon“. Journal of Water and Health 2, Nr. 2 (01.06.2004): 115–22. http://dx.doi.org/10.2166/wh.2004.0011.
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Aeromonas spp. were detected in samples collected from both untreated groundwater and treated drinking water in Lebanon. Aeromonas spp. levels ranged between 2 and 1,100 colonies per 100 ml in the intake underground well and between 3 and 43 colonies per 100 ml in samples from the distribution system. Samples positive for Aeromonas spp. from the network had a free chlorine level ranging between 0 and 0.4 mg l −1. Multiple antibiotic-resistance was common among the isolated aeromonads; all were resistant to amoxycillin while 92% showed resistance to cephalexin. Haemolysis on blood agar was detected in 52% of the isolates recovered from the distribution network and 81% of isolates from the untreated underground source. The Biolog microbial identification system assigned identities to all of the isolated presumptive aeromonads (at least at the genus level), which was not the case with the API 20NE strips. Differences at the species level were observed when results from the Biolog system were compared with identification based on the MicroSeq 500 16S rDNA sequence analysis. The presence of Aeromonas spp. in drinking water can be an important threat to public health, thus greater awareness of Aeromonas strains as potential enteropathogens is warranted.
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Lamy, Brigitte, Fréderic Laurent und Angeli Kodjo. „Validation of a partialrpoBgene sequence as a tool for phylogenetic identification of aeromonads isolated from environmental sources“. Canadian Journal of Microbiology 56, Nr. 3 (März 2010): 217–28. http://dx.doi.org/10.1139/w10-006.
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A collection of 50 aeromonads isolated from environmental sources were studied, together with all known Aeromonas nomenspecies, by phenotypic, amplified 16S rDNA restriction analysis (16S rDNA RFLP) and by partial sequence alignment of both 16S rDNA and rpoB genes. Although most of the type strain showed a unique phenotypic pattern, a database constructed on type strain phenotype allowed the identification of only 24% of the isolates. Analysis of 16S rDNA RFLP and the rpoB sequence were almost concordant in identifying environmental isolates at the species level, except for strains belonging to Aeromonas caviae spp., which were not differentiated from Aeromonas aquariorum , nor Aeromonas hydrophila susbsp. dhakensis by 16S rDNA RFLP. In addition, rpoB gene analysis clustered separately a group of isolates found in snails within the A. hydrophila species. In contrast to 16S rDNA RFLP and rpoB, the partial 16S rDNA sequence analysis was weak in resolving species identity. Part of these results, phenotypic and phylogenetic data, showed that Aeromonas molluscorum and Aeromonas sharmana are distant from all other Aeromonas species and that the type species of A. hydrophila subsp. anaerogenes is similar to A. caviae and should be considered synonymous.
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Ashbolt, N. J., G. S. Grohmann und C. S. W. Kueh. „Significance of Specific Bacterial Pathogens in the Assessment of Polluted Receiving Waters of Sydney, Australia“. Water Science and Technology 27, Nr. 3-4 (01.02.1993): 449–52. http://dx.doi.org/10.2166/wst.1993.0390.
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The impact of primary sewage released from Sydney's ocean outfalls and chlorinated tertiary treated sewage effluent discharged into Sydney's main river system (Hawkesbury-Nepean) have been studied for faecal microorganisms over two years. Faecal indicator bacteria and a range of potential bacterial pathogens (Aeromonas spp., Campylobacters, Pseudomonas aeruginosa, Staphylococcus aureus and salmonellae) were also cultured. Diverting primary-treated sewage from cliff edge release to deepwater (80m) ocean release some 3 km offshore resulted in significant reductions in all bacterial groups examined, with spores of Clostridium perfringens (C.p) being the most sensitive indicator of water quality improvement. In contrast, contamination of inshore sediments has not markedly declined. Campylobacters were not isolated from effluents or seawater, and numbers of S. aureus and P. aeruginosa were very low if detected. Inland river waters were dominated by motile aeromonads, and along with C.p were the most resistant organisms to chlorination following tertiary sewage treatment. However, aeromonads appeared to grow throughout the river system. Campylobacters were associated with areas of agricultural input whereas salmonellae appeared to be associated with significant urban sewage input. Of the indicator bacteria, C.p correlated best with salmonellae, while viruses correlated poorly with the bacterial groups examined. Further work is required to identify possible sources of virulent aeromonads, Campylobacters and salmonellae.
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Imziln, Boujamaa. „Occurrence and Antibiotic Resistance of Mesophilic Aeromonas in Three Riverine Freshwaters of Marrakech, Morocco“. Scientific World JOURNAL 1 (2001): 796–807. http://dx.doi.org/10.1100/tsw.2001.284.
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I n order to evaluate the impact of pollution and sewage on the occurrence and antibiotic resistance of mesophilic aeromonads in riverine freshwaters of Marrakech, samples were collected from three rivers (Oukaimeden, Ourika, and Tensift) upstream and downstream from the principal bordering villages. During a 2-year study, indicators of pollution increased dramatically in the downstream waters. Bacterial indicators (faecal coliforms and faecal streptococci) correlated with mesophilic aeromonads only in heavily polluted waters. In low and moderately polluted sources, densities of mesophilic aeromonads were independent of water quality indicators and did not correlate statistically with faecal indicators. Average counts of Aeromonas in low and heavily polluted waters were 2.5 × 103 and 2.1 × 106 colony forming units per 100 ml, respectively. The biochemical identification of 841 isolates indicated a predominance of A. caviae in heavily and moderately polluted water and sediment. A. hydrophila was dominant only in low polluted waters and when the temperature was below 12°C. High densities of A. sobria were found in low, moderately polluted, or cleaned waters and when the water temperature was above 18°C. All selected isolates (total = 841) were tested for antibiotic susceptibility against 21 antibiotics. Antibiotic resistance frequencies recorded were: ampicillin and amoxicillin, 100%; novobiocin, 96%; cefalotin, 81%; colistin, 72%; sulfamethoxazole, 40%; cefamandole, 37%; polymyxin B, 23%; trimethoprim, 17%; erythromycin, 15%; streptomycin, 8%; amoxicillin-clavulanate, 5%. Resistance to cefotaxime, kanamycin, gentamycin, chloramphenicol, tetracycline, oxytetracycline, nalidixic acid, rifampicin, or trimethoprim-sulfamethoxazole was found to be <5%. Antibiotic resistance rates did vary according to the source of a strain’s isolation, and high numbers of antibiotic resistant strains were recorded in polluted samples. Since no correlation between mesophilic aeromonads and conventional faecal pollution indicators was observed in low or moderately polluted waters, and since these freshwaters are used for domestic supply, we propose the use of mesophilic aeromonads as complementary water pollution indicators to ensure the safety of water.
Dissertationen zum Thema "Environmental aeromonads"
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Dey, Bhowmick Uttara. „Isolation and characterization of environmental aeromonads from North Bengal region with a special emphasis on their drug resistance and virulence genes“. Thesis, University of North Bengal, 2021. http://ir.nbu.ac.in/handle/123456789/4354.
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Ferguson, Yvonne. „Survival strategies of Aeromonas salmonicida in aquatic environments“. Thesis, University of Aberdeen, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294445.
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A luminescence-based detection system was developed to study changes in the survival and activity of cells following release from moribund and dead fish. A.salmonicida was chromosomally marked with the genes encoding bacterial luciferase, originally isolated from Vibrio harveyi. Characterisation of the growth and luminescence of the lux-marked strain demonstrated that light was directly proportional to cell biomass concentration during logarithmic growth. The survival of lux-marked and wild type A.salmonicida strains was investigated in sterile sea water at 4°C. The number of culturable cells declined rapidly, but the total number of cells remained relatively constant, suggesting A. salmonicida entered a nonculturable state. The survival of lux-marked A. salmonicida did not significantly differ from that of the wild type strain. A small number of cells remained culturable throughout starvation experiments and luminometry confirmed that the lux-marked cells were metabolically active, possibly surviving by cryptic growth. The viability of putative dormant cells could not be established since these cells could not be reactivated following the addition of a range of substrates. The lux-marked A.salmonicida strain was pathogenic only when injected at high doses. This poor virulence was probably due to loss of the proteinaceous A-layer which is responsible for hydrophobic cell interactions and cell defence against lytic agents. This prevented further studies aimed at determining the virulence of nonculturable cells using this strain. Preliminary experiments indicated the potential of the lux-marked system for studying vertical transmission of A. salmonicida. The main sites for attachment of the lux-marked strain were the gill and skin/mucus regions. Identical results were obtained using a wild type virulent A. salmonicida strain, but significantly higher numbers of cells were recovered from fish tissue.
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Effendi, Irwan. „Survival of Aeromonas salmonicida in the marine environment“. Thesis, Heriot-Watt University, 1994. http://hdl.handle.net/10399/1369.
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Deere, Daniel Alun. „Survival and distribution of Aeromonas salmonicida in aquatic environments“. Thesis, University of Liverpool, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283475.
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Carvalho, Maria João Mendes de. „Diversity of Aeromonas species from different environments in Portugal“. Doctoral thesis, Universidade de Aveiro, 2010. http://hdl.handle.net/10773/976.
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Doutoramento em BiologiaEspécies de Aeromonas encontram-se distribuídas por diferentes habitats, estando especialmente relacionadas com ambientes aquáticos. O seu papel em complicações na saúde humana e animal é reconhecido. De facto, não só pelo seu potencial de virulência, mas também pelos determinantes genéticos de resistência a antibióticos que possam conter, estes organismos constituem uma preocupação na medicina humana e veterinária. Assim, é essencial o estudo da diversidade de espécies de Aeromonas bem como explorar as suas características fenotípicas e genéticas que podem conduzir a impactos negativos. A água constitui um importante veículo de transmissão de microrganismos e espécies de Aeromonas estão amplamente distribuídas em águas tratadas e não tratadas. Em Portugal é ainda comum o consumo de águas não tratadas cuja qualidade, na maioria das vezes, não é sujeita a monitorização, como acontece por exemplo, em explorações agrícolas de gestão familiar. Neste estudo, investigou-se a presença de Aeromonas em águas não tratadas para consumo. Estabeleceu-se também uma linha horizontal de colheitas de diferentes amostras de origem agrícola com o intuito de avaliar a possibilidade de a água ser uma das vias de contaminação de culturas agrícolas e animais por espécies de Aeromonas. Obtiveram-se 483 isolados que foram discriminados por RAPD-PCR. 169 estirpes distintas foram identificadas ao nível da espécie por análise filogenética baseada no gene gyrB. Verificou-se uma frequente ocorrência bem como uma diversidade considerável de espécies de Aeromonas. Em alguns casos, as relações genotípicas entre isolados de diferentes amostras eram muito próximas. Adicionalmente, a maioria das amostras continha diferentes espécies e estirpes distintas da mesma espécie. A. media e A. hydrophila foram as espécies mais ocorrentes. Um grupo de isolados apresentou variantes moleculares de gyrB diferente das conhecidas até agora, o que indica que poderão constituir espécies não descritas. O perfil de susceptibilidade da colecção de Aeromonas a diferentes antibióticos foi estabelecido, constituindo um perfil típico do género, com algumas excepções. Estirpes multirresistentes foram encontradas. A presença de genes tet e bla foi investigada por estudos de PCR, hibridação e, em alguns casos, de sequenciação. Como era esperado, cphA/imiS foi o mais detectado. A detecção de integrões fez-se por PCR e hibridação e a sua caracterização foi feita por sequenciação de DNA; a sua ocorrência foi reduzida. A maioria das estirpes sintetizou enzimas extracelulares com actividade lipolítica e proteolítica que potencialmente contribuem para virulência. A análise por PCR e hibridação permitiram a detecção de vários determinantes genéticos que codificam moléculas possivelmente envolvidas em processos patogénicos. Diversas espécies de Aeromonas apresentando características relacionadas com resistência a antibióticos e potencialmente de virulência estão frequentemente presentes em produtos para consumo humano e animal em Portugal. ABSTRACT: Aeromonas spp. are present in a wide range of ecological niches, being mainly related to aquatic environments. Their role in human and animal health complications is recognised. In fact, not only for their putative virulence but also for the antibiotic resistance genetic determinants Aeromonas may harbour, these organisms constitute an issue of concern in human and veterinary medicine. Thus, it is essential to get knowledge on Aeromonas sp. diversity and on their genotypic and phenotypic characteristics that may lead to negative impacts. Water constitutes a good contamination route for microorganisms and Aeromonas are widespread in untreated and treated waters from different sources. In Portugal there is still an extensive use of untreated water which is not regularly monitored for quality. This is often the case in family smallholding farms. In this study untreated drinking and mineral waters were assessed for their content in Aeromonas spp. Furthermore, a sampling scheme was designed to investigate the occurrence and diversity of Aeromonas sp. in different agricultural correlated sources and to assess the possibility of water being the transmission vehicle between those sources. 483 isolates were obtained and discriminated by RAPD-PCR. Identification at the species level for 169 distinct strains was done by gyrB based phylogenetic analysis. Results demonstrated the frequent occurrence and considerable diversity of Aeromonas spp. In some cases, genotypic close relations were found between isolates from different sources. Also, most samples contained different species and distinct strains of the same species. A. media and A. hydrophila were the most occurring. A group of isolates displayed gyrB gene sequences distinct from the previously known, indicating that they may constitute representatives of non-described species. The antibiotic susceptibility profile of the aeromonads collection was established and constituted a typical profile of the genus, although few exceptions. Multiresistance patterns were found. The presence of tet and bla genes was investigated by PCR, hybridisation and, in some cases, sequencing analysis. As expected, cphA/imiS was the most detected. Integrons were screened by PCR and hybridisation and characterised by DNA sequencing; low occurrence was recorded. The bulk of strains was able to produce extracellular enzymes with lipolytic and proteolytic activities, which may contribute to virulence. PCR and hybridisation surveys allowed the detection of distinct genetic determinants coding for molecules putatively involved in pathogenic processes. Diverse Aeromonas sp. presenting distinct antibiotic resistance features and putative virulence traits are frequently present in many sources for human and animal consumption in Portugal.
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Rose, Andrew Stuart. „Epidemiological aspects of Aeromonas salmonicida in the marine environment“. Thesis, University of Stirling, 1990. http://hdl.handle.net/1893/21887.
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The epidemiology of Aeromonas salmonicida subsp. salmonicida in the marine environment was investigated. Nutrient resuscitation and infectivity studies did not support a previous claim of dormancy in A. salmonicida and validated the use of colony-forming units (cfu) in survival studies. Survival of A. salmonicida in seawater was assessed and found to be of short duration «10 days). Survival of the bacterium in non-sterile sediment, obtained from beneath a salmon cage, appeared to be limited. The minimum infective dose of A. salmonicida to Atlantic salmon in short duration (1-3 days) bath exposure in sea water was 10' cfu ml-I. Prolonged exposure for three weeks resulted in infection with 102 cfu ml- I. Intragastric intubation of the bacterium established infection with doses >105 cfu. Shedding of A. salmonicida from infected salmon was 105-108 cfu/fish/hr. Survival and shedding results were combined in a computer model. A. salmonicida was predicted to travel >6 km suspended within the water column of a sea loch. Covert infection in freshwater farmed salmon was assessed by ELISA and the standard stress test. Results indicated that ELISA may be useful as a routine monitor of furunculosis infection. The efficacy of dot-blot immunoassay was found to be 108 cfu A. salmonicida in fish kidney tissue. Rainbow trout (Oncorhynchus mykiss) and salmon mucus were not found to inhibit the growth of A. salmonicida supporting recent evidence that fish skin is a site of carriage. In vitro studies suggested that trout serum proteins do not confer protection from fish antibody on A. salmonicida in covert infections. Preliminary work was undertaken to develop a specific DNA probe for A. salmonicida which will allow its detection in environmental samples and carrier fish. A gene library of A. salmonicida was constructed in lambda gtll and screened for "A"-protein with antibodies.
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Silva, Camila MagalhÃes. „Identification phenotypic, genotypic virulence factors and characterization in isolated environmental Aeromonas spp“. Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=14414.
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This study aimed to identify through polyphasic approach (phenotypic and genotypic methods) strains of Aeromonas spp. isolated from surface water and sediment from three different points of the Coco River, Cearà following the salinity gradient of the water. Sampling was conducted between October 2011 and March 2012 each collection consisted of six samples. Aeromonas strains were isolated according to the technique described in the literature Gelatin Phosphate Salt Agar (agar plus GSP 20 μg/mL ampicillin). The physico-chemical parameters (salinity, pH and temperature) of water were on a track that favored not only survival, but also the multiplication of micro-organisms in both sites. Among this sample was isolated 140 strains suspected of Aeromonas and (36.4%) 51 strains were confirmed like Aeromonas spp., wich will be identifiyed until species for fenotipic and genotipic tests. In parallel to the insulation work was done a survey of alternative culture media, where we assessed the efficiency of culture media with different compositions in the characterization of colonies of multiple species of Aeromonas. While the antimicrobial susceptibility profile of Aeromonas strains were resistant 100% penicillin (PEN) and cephalothin (CFL) and 100% antimicrobial susceptibility Amikacin (AMI) and imipenem (IMP) among the nine antimicrobials tested and generally A. caviae was the species that showed resistance to antimicrobials. Among the 27 strains tested (45.8%) were multidrug-resistant by making a multiple resistence antibiotic (MRA) > 2. Five factors of different virulence and all strains were tested had at least one of the five virulence factors tested so that different combinations of virulence factors were found in isolates from the same sample. The results of genetic analysis using primers Aero16S-F and Aero16S-F showed that all isolates identified by conventional microbiological tests were confirmed by PCR and 65.6% of the species identified by conventional biochemical tests were confirmed by Box-PCR method.Este trabalho teve como objetivo principal identificar atravÃs de abordagem polifÃsica (tÃcnicas fenotÃpicas e genotÃpicas) de cepas de Aeromonas spp. isoladas de Ãgua de superfÃcie e sedimento de trÃs pontos distintos do Rio CocÃ, Fortaleza, Cearà seguindo o gradiente de salinidade da Ãgua. Foram realizadas coletas no perÃodo de outubro de 2011 a marÃo de 2012, sendo cada coleta composta por seis amostras. As cepas de Aeromonas foram isoladas de acordo com a tÃcnica descrita na literatura em Ãgar Gelatina Fosfato Sal (Ãgar GSP acrescido de 20 μg/mL de ampicilina). Os parÃmetros fÃsico-quÃmicos (salinidade, pH e temperatura) da Ãgua estavam em uma faixa que favorecia nÃo sà a sobrevivÃncia, mas tambÃm a multiplicaÃÃo dos micro-organismos em dois pontos de coleta. Foram isoladas 140 cepas suspeitas de Aeromonas, 36 (25,7%) foram identificadas atà espÃcie sendo elas: A. caviae, A. media, A. eucrenophila e A. veronii, sendo A. caviae a espÃcie que apareceu com maior frequÃncia. Em paralelo ao trabalho de isolamento foi feita uma pesquisa com dois meios de cultivo alternativos, Ãgar UNISC e Ãgar Amido Ampicilina (AAA), nos quais foi avaliada a eficiÃncia dos meios de cultura com diferentes composiÃÃes, na caracterizaÃÃo de colÃnias de vÃrias espÃcies de Aeromonas. O perfil de suscetibilidade antimicrobiana das cepas de Aeromonas apresentou resistÃncia de 100% a Penicilina (PEN) e Cefalotina (CFL) e 100% de sensibilidade aos antimicrobianos Amicacina (AMI) e Imipenem (IMP) entre os nove antimicrobianos testados e de forma geral A. caviae (38,9%) foi a espÃcie que mais apresentou resistÃncia. Dentre as cepas avaliadas 27 (45,8%) foram multirresistentes por apresentarem um MAR > 2. Foram testados cinco fatores de virulÃncia diferentes e todas as cepas apresentaram pelo menos um desses fatores, de forma que diferentes combinaÃÃes desses fatores foram observadas em isolados provenientes da mesma amostra. Os resultados da anÃlise genÃtica utilizando os iniciadores Aero16S-F e Aero16S-R mostraram que todos os isolados identificados atravÃs de testes clÃssicos de microbiologia foram confirmados por meio da tÃcnica de PCR e 65,6% das espÃcies identificadas por testes bioquÃmicos convencionais foram confirmadas pelo mÃtodo de Box-PCR.
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Lim, Chae-Hong. „The effect of environmental factors on the physiology of Aeromonas hydrophila in lake water“. Thesis, University of Warwick, 1995. http://wrap.warwick.ac.uk/109022/.
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The survival and physiological responses of A. hydrophila were investigated in lake water microcosms under starvation and other stress conditions. Longer survival was shown in filtered- autoclaved water than in Whatman-filtered water than in untreated water. Longer survival also occurred at 4° than at 15° than at 25° than at 30° than at 37°C. The enhanced survival times over unamended controls suggesting that protozoa could be involved in regulating the size of the population of A. hydrophila. Nutrient amendments such as synthetic sewage, casein, ammonium sulphate, serine and glutamine also increased survival of A. hydrophila over that in unamended controls. Organic compounds released from Flavobacterium, Anacystis, and a number of algae also increased survival times of A. hydrophila in Filtered-autoclaved lake water microcosms. Cell size was reduced under starvation conditions and the numbers of cells capable of respiration also decreased but was always greater than their viable count especially if cells were starved at 37°C. This suggests that A. hydrophila is capable of entering a viable but non-culturable phase under starvation conditions. The effects of starvation on two enzymes, phosphatase and exoprotease, both important in the scavenging of nutrients were examined. The activity of alkaline phosphatase and exoprotease both increased under starvation stress with the largest increases being seen at higher starvation temperatures although the viable count often decreased below the limits of detection at the same time. Nutrient amendments, such as a variety of carbon and nitrogen sources, led to an increase in activity of both enzymes and also led to induction of alkaline phosphatase activity in cells grown in high phosphate medium to repress alkaline phopsphatase activity. This is an obvious indicator that derepression of alkaline phosphatase and synthesis of the enzyme could occur under these conditions in lake water microcosms. Exoprotease activity was also increased upon the addition of single nutrient source to the microcosms. Osmotic stress coupled with starvation stress also increased alkaline phosphatase activity and the addition of the osmoprotectant, betaine, also increased activity. In both cases activity increased although the viable count decreased, in some cases below the limits of dection. Exoprotease activity increased in osmotically shocked cells and increased further if betaine was added to the starvation medium. Plasmid transfer could still occur between A. hydrophila and Escherichia coli in unamended and lake water microcosms amended with carbon and some nitrogen sources. The transfer of the F group plasmid R1drd19 was temperature dependent with no detectable transfer occurring at temperatures below 15° C even in nutrient broth. Plasmid transfer was dependent upon the size of the donor and recipient populations with no detectable transfer occurring at low population densities but transfer at high densities shows that even under prevailing environmental conditions the transfer of F-plasmids was possible between E. coli and A. hydrophila. The changes in protein fingerprints of cell and periplasm extracts under starvation and other stresses were examined using two-dimensional gel electrophoresis. Several starvation specific proteins were identified on the gels and some proteins which were only transiently produced were noted. The N-terminal sequences of two stress proteins produced in response to starvation and ethanol and heat stress were obtained from the gels. Alkaline phosphatase one of the key proteins in the response to stress was also identified by colourimetric staining of two-dimensional gels. The survival of A. hydrophila under starvation and other stresses is dependent upon the sequential synthesis of many proteins, including alkaline phosphatase.
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Morgan, Elizabeth M. Ms. „Salmonella and Aeromonas Contamination in a 303(d) Listed Water Body Compared to Fecal Indicators & Water Quality Parameters“. Digital Commons @ East Tennessee State University, 2017. https://dc.etsu.edu/honors/370.
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Since the passage of the Clean Water Act, concern about surface water quality has increased. Reducing exposure to pathogens and adverse impacts on human health because of contact with surface waters has become the focus of many regulatory agencies. Fecal pollution is often a cause of surface water impairment. Fecal indicators, such as fecal coliforms and Escherichia coli, are used as surrogates to evaluate the presence or absence of fecal pollution. However, a growing body of research has shown that these species lack key characteristics necessary to be adequate indicators. As such, explorations into the efficacy of indicator species in predicting fecal pollution in water are necessary. Sinking Creek is a tributary of the Watauga River Watershed, located in Northeast Tennessee. Approximately ten miles of Sinking Creek have been placed on the national 303(d) list for fecal pollution, denoting the presence of fecal contamination exceeding the regulatory limit. Salmonella and Aeromonas are two enteric pathogens that would be expected to be detected in fecally contaminated waters. The primary objective of this study was to detect the presence of Salmonella and Aeromonas in Sinking Creek. The secondary objective was to evaluate their relationship with fecal coliforms, E. coli, and water quality parameters. Six study sites along Sinking Creek were sampled and standard methods were used to enumerate Salmonella and Aeromonas. Samples for Salmonella were collected for 8 months, while samples for Aeromonas were collected for seven. Salmonella and Aeromonas were present in Sinking Creek. Salmonella had the highest concentration at site 2 (the most downstream site), and was detected during all months of the study except for November. Salmonella concentrations varied by site. Aeromonas was present only during colder months, and had the highest concentration at site 2. Both Salmonella and Aeromonas show qualitative relationships with water quality parameters, such as dissolved oxygen and conductivity. However, statistically significant correlations of Salmonella and Aeromonas with water quality parameters were not observed. The lack of statistical significance is partially due to large variability and a small data set. Neither Salmonella or Aeromonas exhibited a relationship with fecal coliforms or E. coli. Therefore, fecal coliforms and E. coli may not be adequate indicator species for the presence of Salmonella, Aeromonas and possibly other waterborne pathogens. Traditional indicator species may inflate risk of pathogen exposure. Thus, many water bodies may be unnecessarily deemed as impaired. The results from this study can be used to guide further research regarding covariates influencing pathogen densities at fecally contaminated sites, as well as to guide decisions regarding impaired surface waters and management techniques.
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Arambewela, Mahendranath K. J. „The Fate of Aeromonas hydrophila in a Model Water Distribution System Biofilm Annular Reactor“. Cincinnati, Ohio : University of Cincinnati, 2008. http://rave.ohiolink.edu/etdc/view.cgi?acc_num=ucin1227220557.
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Thesis (M.S.)--University of Cincinnati, 2008.Advisor: Margaret Kupferle Ph. D. (Committee Chair), Steven Buchberger Ph. D. (Committee Member), Mark Rodgers Ph. D. (Committee Member), Randy Revetta (Committee Member). Title from electronic thesis title page (viewed Jan. 18, 2009). Includes abstract. Keywords: Aeromonas hydrophila; Biofilm: Biofilm Reactors; Drinking water; Iron coupons; Phospholipid phosphate; Polycarbonate coupons; Water quality. Includes bibliographical references.
Bücher zum Thema "Environmental aeromonads"
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Krovacek, Karel. Aeromonas spp. as foodborne pathogens: Studies on the occurance, and virulence profiles of Aeromonas spp. isolated from foods, drinking water, marine environment and human clinical sources. Uppsala: Sveriges Lantbruksuniversitet, 1996.
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Lim, Chae-Hong. The effect of environmental factors on the physiology of aeromonas hydrophila in lake water. [s.l.]: typescript, 1995.
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Pedonese, F., R. Nuvoloni, F. Forzale, F. Fratini, S. Evangelisti, C. D’Ascenzi und S. Rindi. „Occurrence and antimicrobial susceptibility of aeromonads from maricultured gilthead seabream (Sparus aurata)“. In Animal farming and environmental interactions in the Mediterranean region, 205–9. Wageningen: Wageningen Academic Publishers, 2012. http://dx.doi.org/10.3920/978-90-8686-741-7_25.
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Marathe, Nachiket P., und Michael S. Bank. „The Microplastic-Antibiotic Resistance Connection“. In Microplastic in the Environment: Pattern and Process, 311–22. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-78627-4_9.
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AbstractMicroplastic pollution is a big and rapidly growing environmental problem. Although the direct effects of microplastic pollution are increasingly studied, the indirect effects are hardly investigated, especially in the context of spreading of disease and antibiotic resistance genes, posing an apparent hazard for human health. Microplastic particles provide a hydrophobic surface that provides substrate for attachment of microorganisms and readily supports formation of microbial biofilms. Pathogenic bacteria such as fish pathogens Aeromonas spp., Vibrio spp., and opportunistic human pathogens like Escherichia coli are present in these biofilms. Moreover, some of these pathogens are shown to be multidrug resistant. The presence of microplastics is known to enhance horizontal gene transfer in bacteria and thus, may contribute to dissemination of antibiotic resistance. Microplastics can also adsorb toxic chemicals like antibiotics and heavy metals, which are known to select for antibiotic resistance. Microplastics may, thus, serve as vectors for transport of pathogens and antibiotic resistance genes in the aquatic environment. In this book chapter, we provide background information on microplastic biofouling (“plastisphere concept”), discuss the relationship between microplastic and antibiotic resistance, and identify knowledge gaps and directions for future research.
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Kompanets, Eduard, und Viktoria Lavrynenko. „ECOSYSTEM CONNECTIONS AND FISH HEALTH“. In Priority areas for development of scientific research: domestic and foreign experience. Publishing House “Baltija Publishing”, 2021. http://dx.doi.org/10.30525/978-9934-26-049-0-40.
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Ecosystems are subject to many human influences. The balance between species is disturbed due to interference with the aquatic environment. Due to environmental pollution, its impact on fish and other aquatic organisms changes. This affects ecosystem connections. Changes in the environment also change the adaptive capacity of fish, leading to impaired health. Also, there is a need to study the protective capabilities of fish from the naturally occurring opportunistic species Aeromonas hydrophila, which causes infections in them. In natural hydrobiocenoses, fish, as well as pathogens of its diseases (aeromonads) are components of food chains formed by evolution. Literature sources prove that aeromonads are normally present in microbial associations of benthic microflora as a normal saprophytic component of hydroecosystems. These bacteria feed on organic residues that are concentrated at the bottom of water bodies and perform a sanitary function, like other similar types of microorganisms. The health of fish depends on their ability to adapt to the environment. Usually in the wild, fish are rarely susceptible to disease. Local populations for a long time of coexistence have formed a certain balance with other species, including parasitic. The balance is reflected by a certain rate of abundance between species. Imbalance due to fishing from the reservoir, or, conversely, with an artificial increase in numbers, leads to changes in the aquatic environment. Changes in the habitat of fish affect themselves. Fish health is changing. In nature, such a disease as aeromonosis is an ecological concept. Violation of the ecological conditions of the species leads to stress, and reduced immunity in fish, leads to fish disease. In aeromonad infections with weak symptoms in carp, a decrease in biological parameters was observed: growth, body weight, fatness and survival (57.1%). The number of blood cells in diseased fish decreased, especially leukocytes and lymphocytes. The percentage of T- and B-lymphocytes in the blood of carp-infected carp increased. The introduction of the bacterium stimulated the immune response – an increase in the percentage of T-lymphocytes. The percentage of B cells did not increase significantly. In diseased fish, the percentage and number of low-activity T-lymphocytes increased, which corresponded to the presence of an immune response to the bacterium. The values of antibacterial activity of blood serum (BASC) in both groups of fish did not change.
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Pedonese, F., R. Nuvoloni, F. Forzale, F. Fratini, S. Evangelisti, C. D’Ascenzi und S. Rindi. „Occurrence and antimicrobial susceptibility of aeromonads from maricultured gilthead seabream (Sparus aurata)“. In Animal farming and environmental interactions in the Mediterranean region, 205–9. Brill | Wageningen Academic, 2011. http://dx.doi.org/10.3920/9789086867417_027.
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Ghosh, Rajarshi, und Sumit Homechaudhuri. „Seasonal disease occurrence, mortality and survival of adults and fingerlings of Channa punctatus (Bloch) by artificial inoculations of two strains of aeromonads“. In Contemporary Health Issues and Environmental Impact, 102–10. Lincoln University College, 2018. http://dx.doi.org/10.31674/books.2018.chiei.ch10.
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Erkmen, Osman. „Isolation and counting of Aeromonas hydrophila“. In Microbiological Analysis of Foods and Food Processing Environments, 285–90. Elsevier, 2022. http://dx.doi.org/10.1016/b978-0-323-91651-6.00009-4.
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Beaz, Roxana, und Mara Jos. „Molecular Detection and Characterization of Furunculosis and Other Aeromonas Fish Infections“. In Health and Environment in Aquaculture. InTech, 2012. http://dx.doi.org/10.5772/29901.
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„Black Bass Diversity: Multidisciplinary Science for Conservation“. In Black Bass Diversity: Multidisciplinary Science for Conservation, herausgegeben von Jeffery S. Terhune und Benjamin H. Beck. American Fisheries Society, 2015. http://dx.doi.org/10.47886/9781934874400.ch28.
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<em>Abstract</em>.—Disease issues relevant to black bass populations arise from infectious as well as noninfectious etiologies. While disease outbreaks can occur via direct means, as is the case with primary pathogens, mortality events can also be linked to factors that disrupt the delicate balance between the environment, host, and pathogen. Indeed, black bass are found in a variety of geographies and habitats, and irrespective of their locale, fish are subject to environmental fluctuations, such as changes in dissolved oxygen, temperature, and water quality, as well as physical affronts, such as handling and confinement. These and other associated stressors can disrupt homeostasis and result in physiologic perturbations that are central to the pathophysiology of disease in black bass. Many pathogens that affect black bass are ubiquitous and opportunistic and commonly have limited impacts on populations as a whole unless a degradation of environmental conditions occurs that predispose fish to disease or exacerbate disease development. Examples include common aquatic bacterial pathogens (e.g., <em>Aeromonas</em> sp. and <em>Flavobacterium columnare</em>) and fungal and parasitic infestations, especially commensal protozoan parasites. In recent years, viral pathogens have been linked to large-scale fish mortalities in extensive, natural habitats as well as managed recreational impoundments. The underlying mechanisms behind these outbreaks remain largely undefined, yet significant concerns regarding biosecurity practices have surfaced due to the tremendous economic impacts that black bass fisheries support. Additionally, some grossly obvious phenotypic alterations of unknown etiologies (e.g., neoplasms and hyperpigmentation) may be indicative of environmental concerns that warrant further exploration.
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„Conservation, Ecology, and Management of Catfish: The Second International Symposium“. In Conservation, Ecology, and Management of Catfish: The Second International Symposium, herausgegeben von EDWARD N. SISMOUR, M. DAVID CROSBY, SCOTT H. NEWTON und MICHAEL L. FINE. American Fisheries Society, 2011. http://dx.doi.org/10.47886/9781934874257.ch21.
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<em>Abstract</em>.—U.S. Game and Fish agencies and farm-pond owners throughout the United States use commercially produced channel catfish <em>Ictalurus punctatus </em>fingerlings transported from the southern United States for supplemental stocking. We conducted six trials to examine whether pathogen load, body condition, and select environmental factors influence fingerling survival following transport and cage stocking. Fingerlings were sampled prior to stocking and weekly for the following 3 weeks. Weights and lengths were measured, and a relative condition index was used to quantify body condition. Skin scrapings and gill clippings were examined microscopically for pathogens, and posterior kidney was assayed for <em>Aeromonas hydrophila</em>. Mortality was either less than 10% (four trials) or catastrophic (two trials). A Columnaris disease epizootic was associated with ~50% mortality in one trial, and a red sore disease epizootic was associated with ~80% mortality in another. Body condition or other pathogens, present initially or acquired in study ponds, were not associated with high mortality. The first week appears to be critical for the survival of channel catfish fingerlings following transport.
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Jeppesen, Claus. „Chapter 8 Media for Aeromonas spp., Plesiomonas shigelloides and Pseudomonas spp. from food and environment“. In Culture Media for Food Microbiology, 111–27. Elsevier, 1995. http://dx.doi.org/10.1016/s0079-6352(05)80010-4.
Der volle Inhalt der QuelleKonferenzberichte zum Thema "Environmental aeromonads"
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TUMAŠEVIČIŪTĖ, Rasa, und Gytautas IGNATAVIČIUS. „Bacteria from wastewater: potential producers of polyhydroxyalkanoates in Vilnius, Lithuania“. In 12th International Conference “Environmental Engineering”. VILNIUS TECH, 2023. http://dx.doi.org/10.3846/enviro.2023.928.
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Polymers are currently used as a major raw material in industry, but they are quickly discharged into the environment and cause significant pollution. To tackle this environmental pollution problem, particular attention is being funded to biodegradable polymers, namely polyhydroxyalkanoates (PHAs) produced by microorganisms. This research detects PHA-producing bacteria from the Vilnius City municipal wastewater treatment plant. We confirmed 5 PHA-positive strains belonging to the following genera: Brachymonas, Aeromonas, Enterobacter, Pseudomonas. One of the isolates, Aeromonas media, is a promising strain to produce PHAs with production values ranging up to 0.544 g/L. Bacteria producing more than 0.300 g/L are considered useful for the industrial production of bioplastics. We recommend large-scale studies on this strain to assess their use in the industrial production of biopolymers to develop highimpact bioconversion processes of industrial relevance.
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Ciric, Milica, Vladimir Šaraba, Clémence Budin, Tjalf de Boer, Jelena Milovanovic und Jasmina Nikodinovic-Runic. „Bacteria in drinking and bathing mineral waters of Serbia with polymer-degrading potential“. In 2nd International Conference on Chemo and Bioinformatics. Institute for Information Technologies, University of Kragujevac, 2023. http://dx.doi.org/10.46793/iccbi23.091c.
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Three mineral water occurrences, captured by wells with a depth of 6.5-442.5 m and used for drinking and bathing purposes, were sampled and cultivated under conditions favouring the growth of anaerobic, microaerophilic or CO2 bacteria, in order to capture predominantly anaerobic portion of the bacteriome, which is dominant in water and soils. Cultivated bacteria were identified by next-generation 16S sequencing and their biotechnological potential in plastics and lignocellulose degradation was explored. Most abundant genera detected in examined samples mainly belong to facultative anaerobes that are common representatives of water and soil environments. In total, 17 genera were detected with a relative abundance over 1% in all three samples, including Aeromonas, Exiguobacterium, Comamonas and Acinetobacter. Half of the screened isolates demonstrated growth on at least one plastic or lignocellulosic polymer, with one isolate demonstrating growth on all tested substrates, one demonstrating carboxymethyl cellulose- and one arabinoxylan-degrading ability. Some of the representatives of genera identified with high relative abundance in mineral water samples, such as Aeromonas, Klebsiella, Escherichia, Salmonella, Enterobacter, Pseudomonas and Staphylococcus, have been previously documented to have pathogenic potential. Due to the use of investigated mineral waters for drinking and bathing, the health risk from such bacteria in these occurrences needs to be continuously monitored, while, on the other hand, mineral waters deserve special attention in the future from the aspect of screening for biotechnologically relevant enzymes.