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1.
PLoS One ; 14(8): e0221344, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31419250

RESUMO

Aeromonas sobria is a pathogen causing food-borne illness. In immunocompromised patients and the elderly, A. sobria can leave the intestinal tract, and this opportunistically leads to severe extraintestinal diseases including sepsis, peritonitis, and meningitis. To cause such extraintestinal diseases, A. sobria must pass through the intestinal epithelial barrier. The mechanism of such bacterial translocation has not been established. Herein we used intestinal (T84) cultured cells to investigate the effect of A. sobria serine protease (ASP) on junctional complexes that maintain the intercellular adhesion of the intestinal epithelium. When several A. sobria strains were inoculated into T84 monolayer grown on Transwell inserts, the strain with higher ASP production largely decreased the value of transepithelial electrical resistance exhibited by the T84 monolayer and markedly caused bacterial translocation from the apical surface into the basolateral side of T84 monolayer. Further experiments revealed that ASP acts on adherens junctions (AJs) and causes the destruction of both nectin-2 and afadin, which are protein components constituting AJs. Other studies have not revealed the bacterial pathogenic factors that cause the destruction of both nectin-2 and afadin, and our present results thus provide the first report that the bacterial extracellular protease ASP affects these molecules. We speculate that the destruction of nectin-2 and afadin by the action of ASP increases the ability of A. sobria to pass through intestinal epithelial tissue and contributes to the severity of pathological conditions.


Assuntos
Aeromonas/patogenicidade , Proteínas de Bactérias/metabolismo , Doenças Transmitidas por Alimentos/patologia , Mucosa Intestinal/patologia , Serina Proteases/metabolismo , Aeromonas/metabolismo , Translocação Bacteriana , Técnicas de Cultura de Células , Linhagem Celular , Doenças Transmitidas por Alimentos/microbiologia , Humanos , Mucosa Intestinal/citologia , Cinesina/metabolismo , Miosinas/metabolismo , Nectinas/metabolismo
2.
J Food Sci ; 84(8): 2250-2255, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31313323

RESUMO

The ability to produce various extracellular enzymes is considered as an important virulence feature in Aeromonas spp., in addition to producing specific virulence factors such as aerolysin and hemolysin. In this study, the effect of salinity and pH on the production of extracellular virulence factors by Aeromonas was investigated. Aeromonas was obtained from different food sources. A comparative study of the activities of extracellular enzymes secreted by these bacteria at different environmental conditions can widen our understanding on their pathogenicity. The activities of various extracellular enzymes such as amylase, gelatinase, and caseinase, which are implicated as virulence factors, were measured in vitro by calculating the enzymatic activity index (EAI) of each enzyme using standard laboratory protocols. For all enzymes, a significant change (P < 0.05) in the EAI was observed when the concentration of NaCl in the media increased from 0.5% to 3%. Among three enzymes tested, caseinase was found to be affected the most by salinity, with a significant difference in EAI when NaCl concentration in the media increased from 0.5% to 2%. Similarly, amylase was found to be affected the most by acidity. The pH values ranging from 6 to 9 did not exert any significant change in EAI of amylase; however, a pH value of 5 had a significant effect. Overall, compared to salinity, the change in pH was found to be less effective in controlling the extracellular virulence factor production in Aeromonas. PRACTICAL APPLICATIONS: The practical application is to minimize the extracellular virulence factor production by Aeromonas in food commodities by altering the salt content and pH. The results demonstrate that an increase in salinity and a decrease in pH can minimize the extracellular virulence factor production by Aeromonas spp.


Assuntos
Aeromonas/metabolismo , Proteínas de Bactérias/metabolismo , Cloreto de Sódio/metabolismo , Fatores de Virulência/metabolismo , Aeromonas/genética , Proteínas de Bactérias/genética , Toxinas Bacterianas/genética , Toxinas Bacterianas/metabolismo , Microbiologia de Alimentos , Proteínas Hemolisinas/genética , Proteínas Hemolisinas/metabolismo , Concentração de Íons de Hidrogênio , Proteínas Citotóxicas Formadoras de Poros/genética , Proteínas Citotóxicas Formadoras de Poros/metabolismo , Salinidade , Cloreto de Sódio/análise , Fatores de Virulência/genética
3.
PLoS One ; 14(6): e0214035, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31163020

RESUMO

The genetic determinants of bacterial pathogenicity are highly variable between species and strains. However, a factor that is commonly associated with virulent Gram-negative bacteria, including many Aeromonas spp., is the type 3 secretion system (T3SS), which is used to inject effector proteins into target eukaryotic cells. In this study, we developed a bioinformatics pipeline to identify T3SS effector proteins, applied this approach to the genomes of 105 Aeromonas strains isolated from environmental, mutualistic, or pathogenic contexts and evaluated the cytotoxicity of the identified effectors through their heterologous expression in yeast. The developed pipeline uses a two-step approach, where candidate Aeromonas gene families are initially selected using Hidden Markov Model (HMM) profile searches against the Virulence Factors DataBase (VFDB), followed by strict comparisons against positive and negative control datasets, greatly reducing the number of false positives. This approach identified 21 Aeromonas T3SS likely effector families, of which 8 represent known or characterized effectors, while the remaining 13 have not previously been described in Aeromonas. We experimentally validated our in silico findings by assessing the cytotoxicity of representative effectors in Saccharomyces cerevisiae BY4741, with 15 out of 21 assayed proteins eliciting a cytotoxic effect in yeast. The results of this study demonstrate the utility of our approach, combining a novel in silico search method with in vivo experimental validation, and will be useful in future research aimed at identifying and authenticating bacterial effector proteins from other genera.


Assuntos
Aeromonas/patogenicidade , Sistemas de Secreção Tipo III/metabolismo , Fatores de Virulência/toxicidade , Aeromonas/genética , Aeromonas/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/toxicidade , Biologia Computacional/métodos , Simulação por Computador , Genoma Bacteriano , Saccharomyces cerevisiae/citologia , Saccharomyces cerevisiae/efeitos dos fármacos , Fatores de Virulência/genética
4.
J Appl Microbiol ; 127(3): 921-931, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31211898

RESUMO

AIMS: This investigation was undertaken to study the prevalence, enterotoxin gene profile and molecular epidemiology of Aeromonads from various sources of water (182) and fish (173). METHODS AND RESULTS: A total of 116 Aeromonas sp. were isolated, of which 48 (26·37%) were from water and 68 (34·62%) were from fish samples collected from retail markets and fish farms. The Aeromonads were recovered from all types of water sources viz. drinking water (13%), surface waters (26%) and fish ponds (69%). The most prevalent species recovered from drinking water was A. hydrophila, from fish ponds it was A. caviae, from surface water sources A. hydrophila and A. caviae were recovered more frequently, and A. hydrophila and A. veronii bv. sobria were isolated predominantly from gills of fish samples. On multiplex PCR analysis for the detection of enterotoxin genes (act, alt, ast), the above mentioned Aeromonas species frequently contained enterotoxin genes, irrespective of their sources. From isolates across all the sources, act (63%) and alt (57%) genes were encountered more frequently than ast (6%). The enterobacterial repetitive intergenic consensus sequences polymerase chain reaction was used for typing of isolates and most of the isolates from water and fish were related, owing to similar ecosystem. CONCLUSION: A wide distribution of enterotoxin genes in Aeromonads from water and fish is a potential public health threat and molecular genotyping can be helpful to study epidemiology of the pathogen. SIGNIFICANCE AND IMPACT OF THE STUDY: A high proportion of isolates recovered from diverse water sources, particularly potable drinking water and fish samples carried one or more enterotoxin genes thereby indicating a potential pathogenic nature of isolates from these sources. The genetic relatedness was detected amongst many isolates recovered from water sources and fish samples indicating circulation of familiar virulent clones in the aquatic environments.


Assuntos
Aeromonas/genética , Enterotoxinas/genética , Peixes/microbiologia , Aeromonas/metabolismo , Animais , Enterotoxinas/biossíntese , Pesqueiros , Peixes/genética , Epidemiologia Molecular , Reação em Cadeia da Polimerase Multiplex
5.
Microb Pathog ; 127: 198-201, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30500410

RESUMO

The Aeromonas genus has several virulence factors associated with the development of diseases in aquatic organisms, leading to losses in aquaculture. One of these factors is the flagella's formation which allows the biofilm's formation that provides the microorganisms a greater pathogenicity, greater protection to certain substances such as antibiotics. The aim of the study was to verify the presence of the fla gene, related to biofilm production in isolates of Aeromonas spp. from fishes and also to determine the best quantification condition of phenotypic biofilm production in vitro. Polymerase Chain Reactions were performed to obtain the amplification of the region comprising the fla gene. To determine the best condition for the production biofilm, the microplate adhesion test was carried out under different concentrations of TSB broth and it combined with glucose. Of the 43 isolates of Aeromonas spp. analyzed, 28 were positive for the fla gene and, in the quantification of the biofilm, all these were able to form biofilm in the TSB broth without dilution and without addition of glucose, being this the best condition tested. It was observed that the isolates of Aeromonas spp. analyzed have potential for biofilm formation, and hence potential for virulence.


Assuntos
Aeromonas/crescimento & desenvolvimento , Biofilmes/crescimento & desenvolvimento , Meios de Cultura/química , Flagelos/genética , Glucose/metabolismo , Aeromonas/genética , Aeromonas/isolamento & purificação , Aeromonas/metabolismo , Animais , Doenças dos Peixes/microbiologia , Peixes , Infecções por Bactérias Gram-Negativas/microbiologia , Infecções por Bactérias Gram-Negativas/veterinária , Reação em Cadeia da Polimerase
6.
Appl Environ Microbiol ; 85(3)2019 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-30478230

RESUMO

Using bacteria to transform reactive corrosion products into stable compounds represents an alternative to traditional methods employed in iron conservation. Two environmental Aeromonas strains (CA23 and CU5) were used to transform ferric iron corrosion products (goethite and lepidocrocite) into stable ferrous iron-bearing minerals (vivianite and siderite). A genomic and transcriptomic approach was used to analyze the metabolic traits of these strains and to evaluate their pathogenic potential. Although genes involved in solid-phase iron reduction were identified, key genes present in other environmental iron-reducing species are missing from the genome of CU5. Several pathogenicity factors were identified in the genomes of both strains, but none of these was expressed under iron reduction conditions. Additional in vivo tests showed hemolytic and cytotoxic activities for strain CA23 but not for strain CU5. Both strains were easily inactivated using ethanol and heat. Nonetheless, given a lesser potential for a pathogenic lifestyle, CU5 is the most promising candidate for the development of a bio-based iron conservation method stabilizing iron corrosion. Based on all the results, a prototype treatment was established using archaeological items. On those, the conversion of reactive corrosion products and the formation of a homogenous layer of biogenic iron minerals were achieved. This study shows how naturally occurring microorganisms and their metabolic capabilities can be used to develop bio-inspired solutions to the problem of metal corrosion.IMPORTANCE Microbiology can greatly help in the quest for a sustainable solution to the problem of iron corrosion, which causes important economic losses in a wide range of fields, including the protection of cultural heritage and building materials. Using bacteria to transform reactive and unstable corrosion products into more-stable compounds represents a promising approach. The overall aim of this study was to develop a method for the conservation and restoration of corroded iron items, starting from the isolation of iron-reducing bacteria from natural environments. This resulted in the identification of a suitable candidate (Aeromonas sp. strain CU5) that mediates the formation of desirable minerals at the surfaces of the objects. This led to the proof of concept of an application method on real objects.


Assuntos
Aeromonas/metabolismo , Compostos Férricos/metabolismo , Compostos de Ferro/metabolismo , Ferro/metabolismo , Minerais/metabolismo , Aeromonas/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Biodegradação Ambiental , Corrosão , Genoma Bacteriano , Ferro/química , Oxirredução
7.
Fish Physiol Biochem ; 45(1): 123-131, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30047007

RESUMO

Astronotus ocellatus, commonly called the oscar, is one of the popular cichlids among aquarium hobby. The present study deals with the development and characterization of a new cell line from caudal fin of A. ocellatus. The cell line was cultured in Leibovitz's L-15 medium supplemented with 10% fetal bovine serum at 28 °C. The optimum temperature and FBS concentration for cell growth were tested with temperature ranges from 20 to 37 °C and FBS concentrations of 5-20% at 28 °C. The Astronotus ocellatus fin cell line has been subcultured 45 times since its development and the modal chromosome number (2n) is 48. The cell line is composed mainly of epithelial cells as confirmed by immunocytological technique using anti-cytokeratin antibodies. The cell line was cryopreserved at different passage levels and the revival efficiency showed 80% survival rate. Partial sequence amplification and sequencing of two genes, mitochondrial 16S ribosomal RNA and cytochrome oxidase I, confirmed the origin of cell line. The cell line did not show Mycoplasma contamination. The cells showed good transfection efficiency when transfected with 2 µg of pAcGFP1-N1 expression vector. The extracellular products of fish bacterial pathogens viz., Aeromonas hydrophila and A. caviae, were cytotoxic to AOF cells but were not susceptible to Cyprinid herpes virus 2. The development of AOF cell line will have significant applications in fish virology and will prove useful to isolate pathogens in the event of sudden viral disease outbreak and for the development of vaccines and diagnostic kits.


Assuntos
Nadadeiras de Animais/citologia , Ciclídeos , Aeromonas/metabolismo , Animais , Técnicas de Cultura de Células , Linhagem Celular , Criopreservação , Proteínas de Fluorescência Verde , Herpesviridae , Transfecção
8.
J Med Microbiol ; 67(9): 1271-1278, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30024365

RESUMO

PURPOSE: The taxonomy of Aeromonas keeps expanding and their identification remains problematic due to their phenotypic and genotypic heterogeneity. In this study, we aimed to develop a rapid and reliable polymerase chain reaction-restriction fragment length polymorphism assay targeting the rpoD gene to enable the differentiation of aeromonads into 27 distinct species using microfluidic capillary electrophoresis. METHODOLOGY: A pair of degenerate primers (Aero F: 5'-YGARATCGAYATCGCCAARCGB-3' and Aero R: 5'-GRCCDATGCTCATRCGRCGGTT-3') was designed that amplified the rpoD gene of 27 Aeromonas species. Subsequently, in silico analysis enabled the differentiation of 25 species using the single restriction endonuclease AluI, while 2 species, A. sanarelli and A. taiwanensis, required an additional restriction endonuclease, HpyCH4IV. Twelve type strains (A. hydrophila ATCC7966T, A. caviae ATCC15468T, A. veronii ATCC9071T, A. media DSM4881T, A. allosaccharophila DSM11576T, A. dhakensis DSM17689T, A. enteropelogens DSM7312T, A. jandaei DSM7311T, A. rivuli DSM22539T, A. salmonicida ATCC33658T, A. taiwanensis DSM24096T and A. sanarelli DSM24094T) were randomly selected from the 27 Aeromonas species for experimental validation.Results/key findings. The twelve type strains demonstrated distinctive RFLP patterns and supported the in silico digestion. Subsequently, 60 clinical and environmental strains from our collection, comprising nine Aeromonas species, were used for screening examinations, and the results were in agreement. CONCLUSION: This method provides an alternative method for laboratory identification, surveillance and epidemiological investigations of clinical and environmental specimens.


Assuntos
Aeromonas/genética , Proteínas de Bactérias/genética , Reação em Cadeia da Polimerase/métodos , Fator sigma/genética , Aeromonas/classificação , Aeromonas/isolamento & purificação , Aeromonas/metabolismo , Proteínas de Bactérias/metabolismo , Técnicas de Tipagem Bacteriana , Primers do DNA/genética , Polimorfismo de Fragmento de Restrição , Fator sigma/metabolismo , Especificidade da Espécie
9.
Dis Aquat Organ ; 129(2): 107-116, 2018 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-29972371

RESUMO

Aeromonas dhakensis (Ad) CAIM 1873 growth was evaluated at different conditions and antibiotic susceptibility. Mortality and histopathological damages in hybrid tilapia Oreochromis niloticus × O. mossambicus, and virulence factors caused by Ad bacterial cells and extracellular products (ECPs) were evaluated, and the whole genome was obtained. Ad grew between 0.0 and 5.5% NaCl at a pH of between 4 and 10 and from 4 to 37°C. The lowest minimum inhibitory concentration was found for enrofloxacin (<5 µg ml-1), and bacteria were resistant to erythromycin, amoxicillin and ampicillin. Ad bacterial cells (1.86 × 105 cells g-1) and ECPs (0.462 µg protein fish-1) were highly virulent to challenged hybrid tilapia and caused over 80% mortality at 24 h. The primary clinical sign caused was haemorrhage, and damage was most marked in the spleen, liver, kidney and brain of fish challenged with bacterial cells. To our knowledge, this is the first report that Ad causes pyknotic and karyorrhectic nuclei of erythrocytes in the internal organs of hybrid tilapia, which was the most striking histopathological observation. The virulence of Ad to hybrid tilapia may be primarily related to the activity of haemolysins (hlyA genes) and cytotoxins (aerolysin aerA), along with the production of siderophores and proteases. We also found ß-lactamase, tetracycline and multiple antibiotic resistance genes, as well as adherence, iron acquisition, toxins (aerolysin family, haemolysins) and diverse protease genes.


Assuntos
Aeromonas/patogenicidade , Doenças dos Peixes/microbiologia , Infecções por Bactérias Gram-Negativas/veterinária , Tilápia/genética , Aeromonas/genética , Aeromonas/metabolismo , Animais , Doenças dos Peixes/patologia , Regulação Bacteriana da Expressão Gênica , Genoma Bacteriano , Infecções por Bactérias Gram-Negativas/microbiologia , Infecções por Bactérias Gram-Negativas/patologia , Virulência
10.
Food Chem ; 255: 174-181, 2018 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-29571464

RESUMO

This study investigated the biochemical changes (proteins degradation, total volatile basic nitrogen, biogenic amines, volatile organic compounds, nucleotides catabolism and related enzymes) of bighead carp samples inoculated with four different bacteria (Shewanella putrefaciens, Aeromonas sobria, Acinetobacter bohemicus, and Pseudomonas helmanticensis) during storage at 4 ±â€¯1 °C. A. sobria exhibited the strongest proteolytic activity. A. sobria, P. helmanticensis, and S. putrefaciens were responsible for putrescine production, whereas S. putrefaciens was the sole producer of cadaverine. Alcohols and S-compounds were mainly released by A. sobria and S. putrefaciens, respectively. The fastest degradation rates of hypoxanthine riboside and hypoxanthine were found in samples inoculated with P. helmanticensis and S. putrefaciens. Inosine nucleosidase was mainly resulted by A. sobria, P. helmanticensis and S. putrefaciens, whereas xanthine oxidase was derived from both fish muscle and secretions of P. helmanticensis and S. putrefaciens.


Assuntos
Aminas Biogênicas/metabolismo , Carpas/metabolismo , Carpas/microbiologia , Proteínas de Peixes/metabolismo , Compostos Orgânicos Voláteis/metabolismo , Acinetobacter , Aeromonas/metabolismo , Animais , Aminas Biogênicas/análise , Cadaverina/análise , Cadaverina/metabolismo , Produtos Pesqueiros/microbiologia , Armazenamento de Alimentos/métodos , Hipoxantina/análise , Hipoxantina/metabolismo , Nitrogênio/análise , Nitrogênio/metabolismo , Nucleotídeos/metabolismo , Pseudomonas/metabolismo , Putrescina/análise , Putrescina/metabolismo , Shewanella putrefaciens , Compostos Orgânicos Voláteis/análise
11.
Artigo em Inglês | MEDLINE | ID: mdl-28910566

RESUMO

Halophenols make a group of aromatic compounds that are resistible to biodegradation by environmental microorganisms. In this study, the biodegradation of 4-bromo-, 4-chloro- and 4-fluorophenols was studied with two types of activated sludges (from a small rural plant and from a bigger municipal plant) as an inoculum. Because of their wide use, surfactants are present in the wastewater and inhibitors enhance the biodegradation of different pollutants; the influence of natural surfactants on halophenols' biodegradation was also tested. Both types of activated sludge contained bacterial strains which were active in the halophenols' biodegradation process. The coexistence of surfactants and halophenols in the wastewater does not prevent microorganisms from effective halophenols' biodegradation. Moreover, surfactants can enhance the effectiveness of halophenols' removal from the environment. Different cell surface modifications of two isolated bacterial strains were observed in the same system of halophenols with or without surfactants. Halophenols and surfactants may also induce changes in bacteria cell surface properties.


Assuntos
Hidrocarbonetos Halogenados/análise , Fenóis/análise , Esgotos , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Aeromonas/crescimento & desenvolvimento , Aeromonas/metabolismo , Biodegradação Ambiental , Hidrocarbonetos Halogenados/metabolismo , Modelos Teóricos , Fenóis/metabolismo , Saponinas/química , Esgotos/química , Esgotos/microbiologia , Tensoativos/química , Poluentes Químicos da Água/metabolismo
12.
Sci Rep ; 7(1): 8612, 2017 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-28819178

RESUMO

Aeromonas sobria is opportunistic pathogen frequently found in environment and food. Interfering with its quorum sensing (QS) system could be a promising way to alleviate its virulence. In this study, curcumin liposomes were prepared and their characteristics like particle size, zeta potential, PDI (Polymey Disperse Index), encapsulation efficiency and loading capacity were measured. The quorum sensing inhibitory effect of curcumin liposomes under sub-MIC (Minimum Inhibitory Concentration) on siderophore production, swimming and swarming motility, extracellular proteases, biofilm formation and AHLs (N-acylhomoserine lactones) production of A. sobria were also determined. The results showed that, the curcumin liposomes with high encapsulation capacity (84.51 ± 0.58%) were stable and homogeneous. QS-regulated phenotypes of the pathogen were significantly inhibited by curcumin liposomes. The in silico analysis revealed that the QS system of A. sobria may be inhibited by released curcumin from curcumin liposomes through interacting with the built LuxI type protein and blocking the production of AHLs.


Assuntos
Aeromonas/efeitos dos fármacos , Curcumina/química , Lipossomos/farmacologia , Percepção de Quorum/efeitos dos fármacos , Acil-Butirolactonas/metabolismo , Aeromonas/metabolismo , Aeromonas/fisiologia , Sequência de Aminoácidos , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Lipossomos/química , Lipossomos/ultraestrutura , Testes de Sensibilidade Microbiana , Microscopia Eletrônica de Varredura , Simulação de Acoplamento Molecular , Tamanho da Partícula , Ligação Proteica , Conformação Proteica , Percepção de Quorum/fisiologia , Homologia de Sequência de Aminoácidos
13.
Appl Microbiol Biotechnol ; 101(12): 5163-5173, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28299401

RESUMO

The surfactant sodium lauryl ether sulfate (SLES) is widely used in the composition of detergents and frequently ends up in wastewater treatment plants (WWTPs). While aerobic SLES degradation is well studied, little is known about the fate of this compound in anoxic environments, such as denitrification tanks of WWTPs, nor about the bacteria involved in the anoxic biodegradation. Here, we used SLES as sole carbon and energy source, at concentrations ranging from 50 to 1000 mg L-1, to enrich and isolate nitrate-reducing bacteria from activated sludge of a WWTP with the anaerobic-anoxic-oxic (A2/O) concept. In the 50 mg L-1 enrichment, Comamonas (50%), Pseudomonas (24%), and Alicycliphilus (12%) were present at higher relative abundance, while Pseudomonas (53%) became dominant in the 1000 mg L-1 enrichment. Aeromonas hydrophila strain S7, Pseudomonas stutzeri strain S8, and Pseudomonas nitroreducens strain S11 were isolated from the enriched cultures. Under denitrifying conditions, strains S8 and S11 degraded 500 mg L-1 SLES in less than 1 day, while strain S7 required more than 6 days. Strains S8 and S11 also showed a remarkable resistance to SLES, being able to grow and reduce nitrate with SLES concentrations up to 40 g L-1. Strain S11 turned out to be the best anoxic SLES degrader, degrading up to 41% of 500 mg L-1. The comparison between SLES anoxic and oxic degradation by strain S11 revealed differences in SLES cleavage, degradation, and sulfate accumulation; both ester and ether cleavage were probably employed in SLES anoxic degradation by strain S11.


Assuntos
Desnitrificação , Bactérias Gram-Negativas/metabolismo , Dodecilsulfato de Sódio/análogos & derivados , Aeromonas/isolamento & purificação , Aeromonas/metabolismo , Biodegradação Ambiental , Carbono/metabolismo , Comamonadaceae/isolamento & purificação , Comamonadaceae/metabolismo , Comamonas/isolamento & purificação , Comamonas/metabolismo , Bactérias Gram-Negativas/genética , Bactérias Gram-Negativas/isolamento & purificação , Oxirredução , Pseudomonas/isolamento & purificação , Pseudomonas/metabolismo , Esgotos/microbiologia , Dodecilsulfato de Sódio/química , Dodecilsulfato de Sódio/metabolismo , Tensoativos/química , Tensoativos/metabolismo
14.
Food Chem ; 224: 347-352, 2017 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-28159278

RESUMO

Biochemical and microbial changes after harvest strongly affect the final quality and shelf life of fish and fish products. In this study, the role of microbes in the degradation of adenosine triphosphate (ATP), and the origin of adenosine monophosphate deaminase (AMPD) and acid phosphatase (ACP) in common carp fillets during different stages of chilled storage (at 4°C) were investigated. The content of ATP, ADP, AMP, IMP, HxR, and Hx, the activity of AMPD and ACP, and the total count of viable, Aeromonas, Pseudomonas, H2S-producing bacteria, and lactic acid bacteria were examined. Results indicated that the population of microbial communities in control samples increased with storage time, and Pseudomonas peaked on the 10th day of storage. Changes in AMPD activity were less related to the abundance of microbes during the entire storage period. However, ACP was derived from both fish muscle and microbial secretion during the middle and late stages of storage. Degradation of ATP to IMP was not affected by spoilage bacteria, but the hydrolysis of IMP, and the transformation of HxR to Hx was affected considerably by the spoilage bacteria.


Assuntos
Trifosfato de Adenosina/metabolismo , Carpas/microbiologia , Armazenamento de Alimentos , Alimentos Marinhos/microbiologia , AMP Desaminase/metabolismo , Fosfatase Ácida/metabolismo , Aeromonas/isolamento & purificação , Aeromonas/metabolismo , Animais , Temperatura Baixa , Contagem de Colônia Microbiana , Análise de Alimentos , Contaminação de Alimentos , Microbiologia de Alimentos , Lactobacillus/isolamento & purificação , Lactobacillus/metabolismo , Pseudomonas/isolamento & purificação , Pseudomonas/metabolismo , Alimentos Marinhos/análise
15.
Can J Microbiol ; 63(4): 359-364, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28177792

RESUMO

Bacteria in the genus Aeromonas are primarily aquatic organisms; however, some species can cause diseases in humans, ranging from wound infections to septicemia, of which diarrhea is the most common condition. The ability to use a variety of carbon substrates is advantageous for pathogenic bacteria. Therefore, we used Biolog GN2 microplates to analyze the ability of 103 clinical, predominantly diarrheal, isolates of Aeromonas to use various carbon sources, and we verified whether, among the substrates metabolized by these strains, there were some endogenous to the human intestine. The results indicate that Aeromonas present great diversity in the utilization of carbon sources, and that they preferentially use carbohydrates and amino acids as carbon sources. Among the carbon sources metabolized by Aeromonas in vitro, some were found to be components of intestinal mucin, including aspartic acid, glutamic acid, l-serine, galactose, N-acetyl-glucosamine, and glucose, which were used by all strains tested. Additionally, mannose, d-serine, proline, threonine, and N-acetyl-galactosamine were used by several strains. The potential to metabolize substrates endogenous to the intestine may contribute to Aeromonas' capacity to grow in and colonize the intestine. We speculate that this may help explain the ability of Aeromonas to cause diarrhea.


Assuntos
Aeromonas/metabolismo , Carbono/metabolismo , Metabolismo dos Carboidratos , Carboidratos , Diarreia/etiologia , Humanos , Intestinos/microbiologia
16.
Curr Top Microbiol Immunol ; 399: 87-112, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-27858184

RESUMO

Actin cross-linking toxins are produced by Gram-negative bacteria from Vibrio and Aeromonas genera. The toxins were named actin cross-linking domains (ACD), since the first and most of the subsequently discovered ACDs were found as effector domains in larger MARTX and VgrG toxins. Among recognized human pathogens, ACD is produced by Vibrio cholerae, Vibrio vulnificus, and Aeromonas hydrophila. Upon delivery to the cytoplasm of a host cell, ACD covalently cross-links actin monomers into non-polymerizable actin oligomers of various lengths. Provided sufficient doses of toxin are delivered, most or all actin can be promptly cross-linked into non-functional oligomers, leading to cell rounding, detachment from the substrate and, in many cases, cell death. Recently, a deeper layer of ACD toxicity with a less obvious but more potent mechanism was discovered. According to this finding, low doses of the ACD-produced actin oligomers can actively disrupt the actin cytoskeleton by potently inhibiting essential actin assembly proteins, formins. The first layer of toxicity is direct (as actin is the immediate and the only target), passive (since ACD-cross-linked actin oligomers are toxic only because they are non-functional), and less potent (as bulk quantities of one of the most abundant cytoplasmic proteins, actin, have to be modified). The second mechanism is indirect (as major targets, formins, are not affected by ACD directly), active (because actin oligomers act as "secondary" toxins), and highly potent [as it affects scarce and essential actin-binding proteins (ABPs)].


Assuntos
Actinas/metabolismo , Aeromonas/metabolismo , Aeromonas/patogenicidade , Toxinas Bacterianas/metabolismo , Infecções por Bactérias Gram-Negativas/metabolismo , Vibrioses/metabolismo , Vibrio/metabolismo , Vibrio/patogenicidade , Actinas/química , Aeromonas/genética , Animais , Toxinas Bacterianas/genética , Infecções por Bactérias Gram-Negativas/microbiologia , Interações Hospedeiro-Patógeno , Humanos , Vibrio/genética , Vibrioses/microbiologia , Virulência
17.
J Appl Microbiol ; 121(3): 883-91, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27333573

RESUMO

AIMS: To perform a comparative study for determining the optimum culture method (direct plating or enrichment) and medium (ampicillin dextrin agar (ADA), starch ampicillin agar (SAA), bile salts irgasan brilliant green modified (BIBG-m)) for recovering Aeromonas species from water and shellfish samples. METHODS AND RESULTS: By direct culture, Aeromonas was detected in 65% (13/20) of the water samples and in 54·5% (6/11) of the shellfish samples. However, when a pre-enrichment step was included, the number of positive water samples increased to 75% (15/20) and the ones of shellfish to 90·1% (10/11). The enriched culture significantly favoured (P < 0·05) the isolation of Aeromonas allosaccharophila from water, Aeromonas salmonicida from shellfish and Aeromonas caviae from both types of samples. The most specific (P < 0·05) culture medium for detecting Aeromonas from water was ADA. However, no differences were observed in the case of shellfish samples (P > 0·05). Isolation of Aeromonas media from water was favoured (P < 0·05) in the ADA medium, while SAA enhanced (P < 0·05) the isolation of Aer. salmonicida from shellfish. CONCLUSIONS: The culture method and medium used influenced the recovery of some Aeromonas species from water and shellfish samples. SIGNIFICANCE AND IMPACT OF THE STUDY: This fact should be considered in future prevalence studies to avoid overestimating the above mentioned Aeromonas species.


Assuntos
Aeromonas/crescimento & desenvolvimento , Técnicas Bacteriológicas/métodos , Meios de Cultura/metabolismo , Água Doce/microbiologia , Frutos do Mar/microbiologia , Aeromonas/isolamento & purificação , Aeromonas/metabolismo , Técnicas Bacteriológicas/instrumentação , Meios de Cultura/química
18.
Iran Biomed J ; 20(4): 235-40, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27155016

RESUMO

BACKGROUND: Aeromonas species are Gram-negative ubiquitous bacteria, facultative anaerobic rods that infect both invertebrates and vertebrates. Various fish species develop hemorrhagic disease and furunculosis due to Aeromonas spp. Aeromonas strains generate certain active compounds such as siderophores, which are the final products of non-ribosomal peptide synthetase (NRPS) activity. The present study attempted to investigate the prevalence of Aeromonas isolates in marketed fish sources. We also examined the siderophore production ability of these isolates. METHODS: Among the molecular tools, 16S rRNA analysis was used to identify Aeromonas species and their epidemiological distributions. The hemolytic activity of the strains and biochemical assays were used to confirm the identity of the isolates. We also determined the chemical nature of siderophores in these strains. RESULTS: A total of seven Aeromonas isolates obtained from fish were included to determine the siderophore production. Of 7 isolates, 4 produced siderophore, and their chemical nature was also determined. The siderophore produced by Aeromonas was invariably found to be of hydroxamate. Four Aeromonas isolates were selected for PCR identification of NRPS-encoding gene. The conserved sequence was present in all four selected isolates. Furthermore, siderophores were qualitatively tested for their antibacterial activity against pathogenic bacteria and a significant level of inhibitory activity was observed in siderophores from the four isolates. CONCLUSION: Our results showed the ability of the isolated strains in production of siderophores with a high level of activity against Salmonella paratyphi. These siderophores could find applications in biomedical industries.


Assuntos
Aeromonas/metabolismo , Peixes/microbiologia , Ácidos Hidroxâmicos/metabolismo , Peptídeo Sintases/metabolismo , Sideróforos/biossíntese , Aeromonas/classificação , Aeromonas/isolamento & purificação , Animais , Peptídeo Sintases/genética , Reação em Cadeia da Polimerase , RNA Ribossômico 16S/genética , Salmonella paratyphi A/efeitos dos fármacos , Sideróforos/farmacologia
19.
J Gen Appl Microbiol ; 62(2): 60-7, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27118073

RESUMO

Quorum sensing (QS) is a cell-to-cell communication mechanism through which microbial cells communicate and regulate their wide variety of biological activities. N-acyl homoserine lactones (AHLs) are considered to be the most important QS signaling molecules produced by several Gram-negative bacteria. The present study aimed to screen the AHLs-producing bacteria from spoiled vacuum-packaged refrigerated turbot (Scophthalmus maximus) by biosensor assays, and the profiles of AHLs produced by these bacteria were determined using reversed-phase thin-layer chromatography (RP-TLC) and gas chromatography-mass spectrometry (GC-MS). Effects of exogenous AHLs and QS inhibitor (QSI) on the phenotypes (i.e., extracellular proteolytic activity and biofilm formation) of the AHLs-producing bacteria were also evaluated. Our results demonstrated that eight out of twenty-two isolates were found to produce AHLs. Three of the AHLs-producing isolates were identified as Serratia sp., and the other five were found to belong to the family of Aeromonas. Two isolates (i.e., S. liquefaciens A2 and A. sobria B1) with higher AHLs-producing activities were selected for further studies. Mainly, RP-TLC and GC-MS analysis revealed three AHLs, i.e., 3-oxo-C6-HSL, C8-HSL and C10-HSL were produced by S. liquefaciens A2, while five AHLs, i.e., C4-HSL, C6-HSL, C8-HSL, C10-HSL, and C12-HSL, were produced by A. sobria B1. Moreover, production of AHLs in both bacterial strains were found to be density-dependent, and the AHLs activity reached a maximum level in their middle logarithmic phase and decreased in the stationary phase. The addition of exogenous AHLs and QSI decreased the specific protease activity both of the Serratia A2 and Aeromonas B1. Exogenous AHLs inhibited the biofilm formation of Serratia A2 while it enhanced the biofilm formation in Aeromonas B1. QSI inhibited the specific protease activity and biofilm formation in both bacterial strains.


Assuntos
4-Butirolactona/análogos & derivados , Aeromonas/metabolismo , Linguados/microbiologia , Embalagem de Alimentos , Refrigeração , Serratia/metabolismo , 4-Butirolactona/biossíntese , 4-Butirolactona/farmacologia , Aeromonas/crescimento & desenvolvimento , Aeromonas/isolamento & purificação , Animais , Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Técnicas Biossensoriais/métodos , Microbiologia de Alimentos , Cromatografia Gasosa-Espectrometria de Massas , Fenótipo , Proteólise/efeitos dos fármacos , Percepção de Quorum/efeitos dos fármacos , Alimentos Marinhos/microbiologia , Serratia/crescimento & desenvolvimento , Serratia/isolamento & purificação , Vácuo
20.
Toxins (Basel) ; 8(3)2016 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-26927173

RESUMO

The occurrence of the cyanobacterial toxin cylindrospermopsin (CYN) in freshwater reservoirs is a common phenomenon. However, the biodegradation of this toxin in environmental samples has been observed only occasionally. In this work the biodegradation ability of cylindrospermopsin was investigated based on isolates from lakes with previous cyanotoxin history. Bacterial strains were identified based on the 16S rDNA and rpoD gene comparison. CYN biodegradation was monitored using the HPLC method. The R6 strain identified as Aeromonas sp. was documented as being capable of CYN removal. This biodegradation was dependent on the pH and temperature. Additionally, the stimulation of the growth of the R6 strain in the presence of CYN was indicated. Our discovery supports the hypothesis that (in analogy to the well-known phenomenon of microcystin biodegradation) in lakes dominated by potential CYN-producing cyanobacteria, the processes of microbial utilization of this toxin may occur.


Assuntos
Aeromonas/metabolismo , Toxinas Bacterianas/metabolismo , Uracila/análogos & derivados , Aeromonas/genética , Aeromonas/crescimento & desenvolvimento , Biodegradação Ambiental , DNA Bacteriano/análise , DNA Ribossômico/análise , Concentração de Íons de Hidrogênio , Lagos , Polônia , Temperatura , Uracila/metabolismo , Microbiologia da Água
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