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FEMS Microbiology Letters Sep 1997The S-layers of the Aeromonas spp. studied to date are composed of identical protein subunits which are translocated across the cytoplasmic membrane, periplasm and outer... (Review)
Review
The S-layers of the Aeromonas spp. studied to date are composed of identical protein subunits which are translocated across the cytoplasmic membrane, periplasm and outer membrane to the cell surface, where they are assembled and tethered to the cell via an interaction with the O-polysaccharide side chains of the lipopolysaccharide. Aeromonas S-layers have the ability to bind a number of host factors such as fibronectin, laminin and vitronectin as well as providing resistance to serum killing and protease digestion. Aeromonas mutants unable to produce an S-layer are altered in their ability to cause disease. In the case of Aeromonas salmonicida, the loss of ability to produce an S-layer effectively abolishes virulence. However, in the case of A. hydrophila, the reduction in virulence caused by the loss of the S-layer is less significant.
Topics: Aeromonas hydrophila; Bacterial Outer Membrane Proteins; Crystallization; Virulence
PubMed: 9297815
DOI: 10.1111/j.1574-6968.1997.tb12616.x -
Reviews of Infectious Diseases 1988The importance of the genus Aeromonas in human disease has recently become better appreciated through the use of improved methodologies for the recovery and... (Review)
Review
The importance of the genus Aeromonas in human disease has recently become better appreciated through the use of improved methodologies for the recovery and identification of aeromonads from biologic specimens and as a result of medical studies aimed at determining the clinical significance of these bacteria when isolated from localized and invasive infections of humans. Taxonomic schemes currently allow for the identification of six Aeromonas species (five mesophilic and one psychrophilic), four of the five mesophilic species having been recovered from infectious processes or isolated from clinical material of human origin. Two major categories of human illness attributed to Aeromonas species have been observed: acute gastroenteritis in both pediatric and adult populations and disseminated disease (e.g., bacteremia) in persons with underlying hematologic malignancies or hepatic dysfunctions. Although the role of mesophilic aeromonads as important agents of bacterial gastroenteritis remains unconfirmed because of the inability to fulfill Koch's postulates (no animal model), several lines of compelling clinical and laboratory evidence indicate that these microorganisms are significant enteric pathogens.
Topics: Aeromonas; Bacterial Infections; Gastroenteritis; Humans; Sepsis; Wound Infection
PubMed: 3055195
DOI: 10.1093/clinids/10.5.980 -
Zentralblatt Fur Bakteriologie,... Nov 1988In the Netherlands, aeromonads in drinking water have attracted much attention in recent years. This development was caused by a sudden increase of the Aeromonas density... (Review)
Review
In the Netherlands, aeromonads in drinking water have attracted much attention in recent years. This development was caused by a sudden increase of the Aeromonas density in the drinking water of the municipal Dune Waterworks of The Hague and reports about the possible health significance of these organisms in drinking water. Literature data indicate that representatives of the motile Aeromonas species A. hydrophila, A. sobria and A. caviae generally have been observed in larger percentages of diarrheal feces than in normal stools, with isolation rates ranging from less than 1% to more than 20%. These data and the virulence properties of the aeromonads, viz. hemolytic activity, cytotoxicity and enterotoxicity, as tested in the suckling mouse assay or the rabbit ileal loop, strongly suggest that these aeromonads are potential enteric pathogens for susceptible hosts, including young children and immunocompromised persons. Aeromonads are ubiquitously present in fresh water environments, with densities depending on pollution with sewage, trophic state and temperature. About 100 years ago, bacteria identical with Aeromonas spp. have already been isolated from drinking water. Depletion of free chlorine residuals in drinking water generally results in increasing Aeromonas densities, particularly in the summer months. Investigations in the Netherlands have shown that Aeromonas densities in drinking water increase with increasing residence time. Furthermore, the aeromonads constitute a minor fraction of the heterotrophic bacterial population in drinking water. Growth measurements with pure cultures of A. hydrophila revealed that certain compounds, e.g. oleate as present in soft soap, promote the growth of the organism at substrate concentrations of a few micrograms per liter. Based on a number of surveys on the presence of aeromonads in drinking water, the health authorities in the Netherlands have defined so-called indicative maximum values for Aeromonas densities in drinking water i.e. 20 CFU/100 ml in drinking water at the production plant and 200 CFU/100 ml in drinking water during distribution. Further research is necessary (i) to elucidate the health significance of aeromonads in drinking water and (ii) to define measures for limiting Aeromonas densities in drinking water.
Topics: Aeromonas; Animals; Bacterial Infections; Diarrhea; Feces; Fresh Water; Humans; Netherlands; Virulence; Water Microbiology; Water Supply
PubMed: 3146172
DOI: No ID Found -
International Journal of Food... Dec 1995Aeromonas spp. are Gram-negative rods of the family Vibrionaceae. They are normal water inhabitants and are part of the regular flora of poiquilotherm and homeotherm...
Aeromonas spp. are Gram-negative rods of the family Vibrionaceae. They are normal water inhabitants and are part of the regular flora of poiquilotherm and homeotherm animals. They can be isolated from many foodstuffs (green vegetables, raw milk, ice cream, meat and seafood). Mesophilic Aeromonas spp. have been classified following the AeroKey II system (Altwegg et al., 1990; Carnahan et al., 1991). The major human diseases caused by Aeromonas spp. can be classified in two major groups: septicemia (mainly by strains of A. veronii subsp. sobria and A. hydrophila), and gastroenteritis (any mesophilic Aeromonas spp. but principally A. hydrophila and A. veronii). Most epidemiological studies have shown Aeromonas spp. in stools to be more often associated with diarrhea than with the carrier state; an association with the consumption of untreated water was also conspicuous. Acute self-limited diarrhea is more frequent in young children, in older patients chronic enterocolitis may also be observed. Fever, vomiting, and fecal leukocytes or erythrocytes (colitis) may be present (Janda, 1991). The main putative virulence factors are: exotoxins, endotoxin (LPS), presence of S-layers, fimbriae or adhesins and the capacity to form capsules.
Topics: Aeromonas; Bacterial Adhesion; Bacterial Toxins; Food Microbiology; Gastroenteritis; Hydrogen-Ion Concentration; Temperature; Virulence
PubMed: 8750664
DOI: 10.1016/0168-1605(95)00054-2 -
Carbohydrate Research Apr 2022Presented herein is the synthesis of the Aeromonas veronii disaccharide repeating unit which has been achieved in 11 steps starting from d-fucose and d-galactosamine.
Presented herein is the synthesis of the Aeromonas veronii disaccharide repeating unit which has been achieved in 11 steps starting from d-fucose and d-galactosamine.
Topics: Aeromonas; Aeromonas veronii; Disaccharides; Fucose
PubMed: 35263695
DOI: 10.1016/j.carres.2022.108530 -
Protein Expression and Purification Dec 2021The gene of catechol 1, 2-dioxygenase was identified and cloned from the genome of Oceanimonas marisflavi 102-Na3. The protein was expressed in Escherichia coli BL21...
The gene of catechol 1, 2-dioxygenase was identified and cloned from the genome of Oceanimonas marisflavi 102-Na3. The protein was expressed in Escherichia coli BL21 (DE3) and purified to homogeneity of a dimer with molecular mass of 69.2 kDa. The enzyme was highly stable in pH 6.0-9.5 and below 45 °C and exhibited the maximum activity at pH 8.0 and 30 °C. Being the first characterized intradiol dioxygenase from marine bacteria Oceanimonas sp., the enzyme showed catalytic activity for catechol, 3-methylcatechol, 4-methylcatechol, 3-chlorocatechol, 4-chlorocatechol and pyrogallol. For catechol, K and V were 11.2 μM and 13.4 U/mg of protein, respectively. The enzyme also showed resistance to most of the metal ions, surfactants and organic solvents, being a promising biocatalyst for biodegradation of aromatic compounds in complex environments.
Topics: Aeromonadaceae; Amino Acid Sequence; Bacterial Proteins; Catechol 1,2-Dioxygenase; Catechols; Cloning, Molecular; Escherichia coli; Gene Expression; Genetic Vectors; Hydrogen-Ion Concentration; Kinetics; Molecular Weight; Phylogeny; Protein Multimerization; Pyrogallol; Recombinant Proteins; Sequence Alignment; Sequence Homology, Amino Acid; Substrate Specificity
PubMed: 34454050
DOI: 10.1016/j.pep.2021.105964 -
Microbiology (Reading, England) May 2021The bacterial species is a fish pathogen. Feared by fish farmers everywhere on Earth over the past century, this species has turned out to be more diverse than...
The bacterial species is a fish pathogen. Feared by fish farmers everywhere on Earth over the past century, this species has turned out to be more diverse than initially suspected. While some psychrophilic subspecies cannot grow at temperatures above 25 °C or 30 °C, other mesophilic strains growing up to 37 °C and above are now characterized. Adding to the surprising diversity of this species, some of the mesophilic strains infect mammals and birds. The remarkable diversity is explained in part by the presence of numerous mobile genetic elements, which sculpt and modify the genome of the various strains of this species.
Topics: Aeromonas salmonicida; Animals; Biodiversity; DNA Transposable Elements; Fish Diseases; Fishes; Gram-Negative Bacterial Infections; Temperature
PubMed: 33945463
DOI: 10.1099/mic.0.001052 -
Acta Crystallographica. Section D,... Jan 2022CRISPR-Cas systems are well known host defense mechanisms that are conserved in bacteria and archaea. To counteract CRISPR-Cas systems, phages and viruses have evolved...
CRISPR-Cas systems are well known host defense mechanisms that are conserved in bacteria and archaea. To counteract CRISPR-Cas systems, phages and viruses have evolved to possess multiple anti-CRISPR (Acr) proteins that can inhibit the host CRISPR-Cas system via different strategies. The expression of acr genes is controlled by anti-CRISPR-associated (Aca) proteins that bind to an upstream promoter and regulate the expression of acr genes during transcription. Although the role of Aca as a transcriptional repressor has been demonstrated, the mechanism of action of Aca has not been determined. Here, the molecular mechanism underlying the Aca2-mediated transcriptional control of acr genes was elucidated by determining the crystal structure of Aca2 from Oceanimonas smirnovii at a high resolution of 1.92 Å. Aca2 forms a dimer in solution, and dimerization of Aca2 is critical for specific promoter binding. The promoter-binding strategy of dimeric Aca2 was also revealed by performing mutagenesis studies. The atomic structure of the Aca family shown in this study provides insights into the fine regulation of host defense and immune-escape mechanisms and also demonstrates the conserved working mechanism of the Aca family.
Topics: AIDS-Related Complex; Aeromonadaceae; CRISPR-Associated Proteins; CRISPR-Cas Systems; Crystallography, X-Ray; Epigenetic Repression; Molecular Structure; Mutagenesis; Promoter Regions, Genetic; Transcription, Genetic
PubMed: 34981762
DOI: 10.1107/S2059798321011670 -
Microbial Pathogenesis Mar 2018Aeromonas hydrophila is a freshwater-dwelling zoonotic bacterium that has economic importance in aquaculture. In the past decade, Aeromonas hydrophila has become... (Review)
Review
Aeromonas hydrophila is a freshwater-dwelling zoonotic bacterium that has economic importance in aquaculture. In the past decade, Aeromonas hydrophila has become increasingly important because of its emergence as a food-borne zoonotic pathogen that is resistant to different treatment regimes. Being an aquatic bacterium, Aeromonas hydrophila is frequently subjected to several stressful environmental conditions, including changes in temperature, acidic pH and starvation that challenge its survival. To cope with these stressful conditions, like every cell, A. hydrophila possesses stress response mechanisms, such as alternative sigma factors, two-component systems, heat shock proteins, cold shock proteins, and acid tolerance response systems that eventually lead the fittest to survive. Moreover, the establishment of genetic variations among the strains related to environmental stress is also of great concern. This review presents the understandings based on inter-strain variations and stress response behavior of A. hydrophila that are important to control the increasing outbreaks of this bacterium in both human populations and aquaculture.
Topics: Adaptation, Biological; Adaptation, Physiological; Aeromonas hydrophila; Environmental Exposure; Hydrogen-Ion Concentration; Stress, Physiological; Temperature
PubMed: 29355702
DOI: 10.1016/j.micpath.2018.01.023 -
Systematic and Applied Microbiology Jul 2013Technological advances together with the continuous description of new taxa have led to frequent reclassifications in bacterial taxonomy. In this study, an extensive...
Technological advances together with the continuous description of new taxa have led to frequent reclassifications in bacterial taxonomy. In this study, an extensive bibliographic revision, as well as a sequence analysis of nine housekeeping genes (cpn60, dnaJ, dnaX, gyrA, gyrB, mdh, recA, rpoB and rpoD) and a phenotypic identification of Aeromonas hydrophila subspecies anaerogenes were performed. All data obtained from previous physiological, phylogenetic, and DNA-DNA hybridization studies together with those presented in this study suggested that A. hydrophila subspecies anaerogenes belonged to the species Aeromonas caviae rather than A. hydrophila. Therefore, the inclusion of A. hydrophila subsp. anaerogenes in the species A. caviae is proposed.
Topics: Aeromonas caviae; Aeromonas hydrophila; Bacterial Typing Techniques; DNA, Bacterial; Nucleic Acid Hybridization
PubMed: 23759598
DOI: 10.1016/j.syapm.2013.04.006