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1.
Food Chem ; 301: 125256, 2019 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-31362192

RESUMO

Panela is a natural, unrefined non-centrifugal sugar obtained by intense dehydration of sugarcane juice. Acrylamide, hydroxymethylfurfural (HMF), and furfural were determined in 40 panela samples distributed as granulated and block according to the technological process. Colour, browning, moisture, water activity, pH and antioxidant capacity were also evaluated. Acrylamide ranged between 60 and 3058 µg/kg; granulated panela reporting the highest concentration (812 µg/kg) compared with block panela (540 µg/kg). The lower content in HMF and furfural, the intense dehydration, and the extensive darkening of granulated panela suggested the browning reactions were boosted due to the application of more severe thermal treatments. Principal component analysis showed a significant relationship between the panela presentation and the concentration of the analysed compounds. Benchmark values considering both types of processes would help to establish mitigation initiatives in panela products. The chromatic parameter a* could be used as an indirect index of the acrylamide content in panela.


Assuntos
Acrilamida/análise , Antioxidantes/análise , Fenômenos Químicos , Temperatura Alta , Açúcares/química , Plasmídeos de Bacteriocinas , Cor , Furaldeído/análogos & derivados , Furaldeído/análise , Concentração de Íons de Hidrogênio , Reação de Maillard , Saccharum/química
2.
Math Biosci ; 311: 109-124, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30849409

RESUMO

Competition and coexistence were examined for two bacterial species, each potentially carrying a fitness-reducing, parasitic plasmid that was vertically transmitted with possible loss through segregation. Here, the fitness reduction of hosts was due to a toxin produced by plasmid-bearing cells and inhibiting plasmid-free cells. These populations were placed in a flow reactor habitat representing an idealized mammal gut. It was numerically shown that parasitic plasmids can mediate coexistence of competing host species, in conditions where plasmid-free hosts could not coexist. Numerical construction of a coexistence example suggests that it arises only for a narrow parameter range. In particular, both rates of segregation and the growth costs of plasmid carriage must be relatively low.


Assuntos
Fenômenos Fisiológicos Bacterianos , Plasmídeos de Bacteriocinas , Ecossistema , Modelos Biológicos
3.
Sci Rep ; 7: 42068, 2017 02 06.
Artigo em Inglês | MEDLINE | ID: mdl-28165017

RESUMO

Production of public goods in biological systems is often a collaborative effort that may be detrimental to the producers. It is therefore sustainable only if a small fraction of the population shoulders the cost while the majority reap the benefits. We modelled this scenario using Escherichia coli populations producing colicins, an antibiotic that kills producer cells' close relatives. Colicin expression is a costly trait, and it has been proposed that only a small fraction of the population actively expresses the antibiotic. Colicinogenic populations were followed at the single-cell level using time-lapse microscopy, and showed two distinct, albeit dynamic, subpopulations: the majority silenced colicin expression, while a small fraction of elongated, slow-growing cells formed colicin-expressing hotspots, placing a significant burden on expressers. Moreover, monitoring lineages of individual colicinogenic cells showed stochastic switching between expressers and non-expressers. Hence, colicin expressers may be engaged in risk-reducing strategies-or bet-hedging-as they balance the cost of colicin production with the need to repel competitors. To test the bet-hedging strategy in colicin-mediated interactions, competitions between colicin-sensitive and producer cells were simulated using a numerical model, demonstrating a finely balanced expression range that is essential to sustaining the colicinogenic population.


Assuntos
Plasmídeos de Bacteriocinas/metabolismo , Colicinas/metabolismo , Escherichia coli/metabolismo , Antibacterianos/metabolismo , Bacteriocinas/metabolismo , Escherichia coli/citologia , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Microscopia de Fluorescência/métodos , Modelos Teóricos , Fenótipo , Imagem com Lapso de Tempo
4.
Foodborne Pathog Dis ; 12(11): 873-80, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26397128

RESUMO

The objective of this study was to characterize plasmids coharboring 16S rRNA methylases, blaCTX-M and virulence-associated genes in Escherichia coli and Klebsiella pneumoniae isolates from chickens in China. A total of 32 positive transconjugants exhibited coresistance to amikacin and cefotaxime in E. coli (24/281) and K. pneumoniae (8/93), and were identified by conjugation experiments and S1-pulsed-field gel electrophoresis. Polymerase chain reaction amplification assay detecting resistance genes showed that rmtB or armA gene accompanied with different blaCTX-M genes coexisted on 32 transferred plasmids. The blaCTX-M-98b gene was identified in chicken-derived E. coli and K. pneumoniae for the first time. The association between resistance genes and virulence genes was observed in the transferred plasmids; 68.8% (22/32) transferred resistance plasmids coharboring various virulence genes including traT, iutA, fyuA, msbB, and vagC genes with diverse proportions. Genetic stability tests revealed that 93.8% (30/32) transferred plasmids continued to exist in the host strain after continuous passage of 30 times in 15 days. Furthermore, 87.5% (28/32) conjugants showed no significant differences in growth rates compared with E. coli J53. Results of the growth competition assay showed that conjugants have low fitness cost, which indicated that there were no obvious negative effects on the host's growth. The combination of blaCTX-M-98b-rmtB-traT on 85-kb transferred IncF plasmids in E. coli, and blaCTX-M-14-rmtB-traT on 95-kb transferred IncF plasmids in K. pneumoniae were first identified in this study. These features of plasmids may contribute to the successful spread of resistance and virulence among pathogens of different sources and geographical origins.


Assuntos
Proteínas de Bactérias/genética , Plasmídeos de Bacteriocinas/genética , Galinhas/microbiologia , Escherichia coli/genética , Klebsiella pneumoniae/genética , tRNA Metiltransferases/genética , Amicacina/farmacologia , Animais , Antibacterianos/farmacologia , Proteínas de Bactérias/efeitos dos fármacos , Plasmídeos de Bacteriocinas/efeitos dos fármacos , Cefotaxima/farmacologia , China , Conjugação Genética , Farmacorresistência Bacteriana/genética , Eletroforese em Gel de Campo Pulsado , Escherichia coli/enzimologia , Escherichia coli/isolamento & purificação , Escherichia coli/patogenicidade , Infecções por Escherichia coli/genética , Infecções por Escherichia coli/veterinária , Proteínas de Escherichia coli/genética , Infecções por Klebsiella/genética , Infecções por Klebsiella/veterinária , Klebsiella pneumoniae/enzimologia , Klebsiella pneumoniae/isolamento & purificação , Klebsiella pneumoniae/patogenicidade , Metiltransferases/genética , Testes de Sensibilidade Microbiana , Reação em Cadeia da Polimerase , RNA Ribossômico 16S/análise , RNA Ribossômico 16S/genética , Fatores de Virulência/genética , beta-Lactamases/genética
5.
BMC Microbiol ; 15: 118, 2015 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-26055257

RESUMO

BACKGROUND: Most recent studies of Clostridium perfringens plasmids have focused on toxin-encoding or antibiotic resistance plasmids. To cause intestinal disease, a toxigenic strain must grow in the intestines to levels allowing for sufficient toxin production and this in vivo growth often involves overcoming the normal intestinal microbial population. For this purpose, bacteriocin production might be important. RESULTS: In this study, as the first step in the genetic analysis of a co-existing plasmid with an enterotoxin gene (cpe)-encoding plasmid, the bacteriocin gene-encoding plasmid, pBCNF5603, was completely sequenced. This plasmid has some homology with two previously sequenced C. perfringens plasmids, namely, pCP13 carrying a cpb2 gene and pIP404 carrying a bcn gene. Using recombinant plasmids, the rep gene homologous to the PCP63 gene on pCP13 appeared to be functional. Comparative genomics indicated that the identified rep gene homologs were found on two additional toxin plasmids, pCP-OS1 and pCP-TS1. While functional analysis using recombinant plasmids indicated that pBCNF5603 and pCP13 are likely to be incompatible, the plasmid replication and partitioning region of pBCNF5603 alone was insufficient for stable maintenance of this plasmid. CONCLUSIONS: These findings suggest that pBCNF5603 evolved from recombination events between C. perfringens plasmids and inter-species mobile genetic element(s). In addition, the bcn-encoding plasmid, pBCNF5603, is likely to be included in the Inc family, which includes pCP13 and two variant iota-encoding plasmids. Furthermore, the bcn gene on pBCNF5603 could contribute to gastrointestinal disease induced by enterotoxigenic C. perfringens.


Assuntos
Plasmídeos de Bacteriocinas/genética , Clostridium perfringens/genética , Replicação do DNA , Enterotoxinas/genética , Enterotoxinas/metabolismo , Dados de Sequência Molecular , Análise de Sequência de DNA , Homologia de Sequência do Ácido Nucleico
6.
Zoonoses Public Health ; 62(6): 479-88, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25653018

RESUMO

The presence and transfer of antimicrobial resistance genes from commensal bacteria in companion animals to more pathogenic bacteria may contribute to dissemination of antimicrobial resistance. The purpose of this study was to determine antimicrobial resistance gene content and the presence of genetic elements in antimicrobial resistant Escherichia coli from healthy companion animals. In our previous study, from May to August, 2007, healthy companion animals (155 dogs and 121 cats) from three veterinary clinics in the Athens, GA, USA area were sampled and multidrug-resistant E. coli (n = 36; MDR, resistance to ≥ 2 antimicrobial classes) were obtained. Of the 25 different plasmid replicon types tested by PCR, at least one plasmid replicon type was detected in 94% (34/36) of the MDR E. coli; four isolates contained as many as five different plasmid replicons. Nine replicon types (FIA, FIB, FII, I2, A/C, U, P, I1 and HI2) were identified with FIB, FII, I2 as the most common pattern. The presence of class I integrons (intI) was detected in 61% (22/36) of the isolates with eight isolates containing aminoglycoside- and/or trimethoprim-resistance genes in the variable cassette region of intI. Microarray analysis of a subset of the MDR E. coli (n = 9) identified the presence of genes conferring resistance to aminoglycosides (aac, aad, aph and strA/B), ß-lactams (ampC, cmy, tem and vim), chloramphenicol (cat), sulfonamides (sulI and sulII), tetracycline [tet(A), tet(B), tet(C), tet(D) and regulator, tetR] and trimethoprim (dfrA). Antimicrobial resistance to eight antimicrobials (ampicillin, cefoxitin, ceftiofur, amoxicillin/clavulanic acid, streptomycin, gentamicin, sulfisoxazole and trimethoprim-sulfamethoxazole) and five plasmid replicons (FIA, FIB, FII, I1 and I2) were transferred via conjugation. The presence of antimicrobial resistance genes, intI and transferable plasmid replicons indicate that E. coli from companion animals may play an important role in the dissemination of antimicrobial resistance, particularly to human hosts during contact.


Assuntos
Plasmídeos de Bacteriocinas/farmacologia , Gatos/microbiologia , Cães/microbiologia , Farmacorresistência Bacteriana Múltipla/genética , Escherichia coli/efeitos dos fármacos , Animais , Animais Domésticos , Antibacterianos/farmacologia , Plasmídeos de Bacteriocinas/genética , Escherichia coli/genética , Escherichia coli/isolamento & purificação , Genes Bacterianos/efeitos dos fármacos , Georgia , Humanos , Integrons , Animais de Estimação , Plasmídeos , Reação em Cadeia da Polimerase , Replicon/genética
7.
Plasmid ; 77: 7-16, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25450765

RESUMO

We sequenced the complete 7118 bp circular plasmid pColE3-CA38 (pColE3) from Escherichia coli, located the previously identified colicin components together with two new ORFs that have homology to mobilization and transfer proteins, and found that pColE3 is highly similar to a plasmid present in enterohemorrhagic E. coli O111. We also found that unusual aspects of the plasmid include the inability to be completely digested with restriction endonucleases and asymmetric Phred DNA sequencing quality scores, with significantly lower scores in the forward direction relative to the colicin and immunity proteins consistent with plus (+) strand DNA. Comparing the A260 with picogreen double-stranded DNA (dsDNA) fluorescence and oligreen single-stranded DNA (ssDNA) fluorescence as well as metachromatic staining by acridine orange, we found that the undigested pColE3 DNA stains preferentially as ssDNA and that it coexists with dsDNA. We also identified ssDNA in pColE5 and pColE9 but not in pColE1. Colicin plasmids producing ssDNA may represent a new subclass of rolling-circle replication plasmids and add to the known similarities between colicins and filamentous phage.


Assuntos
Plasmídeos de Bacteriocinas/genética , DNA Bacteriano/metabolismo , DNA de Cadeia Simples/metabolismo , Escherichia coli/genética , Laranja de Acridina/metabolismo , Sequência de Bases , Corantes/metabolismo , Fluorescência , Dosagem de Genes , Dados de Sequência Molecular , Mapeamento por Restrição , Análise de Sequência de DNA
8.
ACS Synth Biol ; 4(3): 299-306, 2015 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-24896372

RESUMO

We designed Lactococcus lactis to detect Enterococcus faecalis. Upon detection, L. lactis produce and secrete antienterococcal peptides. The peptides inhibit enterococcal growth and reduce viability of enterococci in the vicinity of L. lactis. The enterococcal sex pheromone cCF10 serves as the signal for detection. Expression vectors derived from pCF10, a cCF10-responsive E. faecalis sex-pheromone conjugative plasmid, were engineered in L. lactis for the detection system. Recombinant host strains were engineered to express genes for three bacteriocins, enterocin A, hiracin JM79 and enterocin P, each with potent antimicrobial activity against E. faecalis. Sensitive detection and specific inhibition occur both in agar and liquid media. The engineered L. lactis also inhibited growth of multidrug-resistant E. faecium strains, when induced by cCF10. The presented vectors and strains can be components of a toolbox for the development of alternative antibiotic technologies targeting enterococci at the site of infection.


Assuntos
Antibacterianos/farmacologia , Plasmídeos de Bacteriocinas/genética , Bacteriocinas/farmacologia , Técnicas Biossensoriais/métodos , Enterococcus faecalis/efeitos dos fármacos , Enterococcus faecalis/isolamento & purificação , Lactococcus lactis/genética , Antibacterianos/metabolismo , Bacteriocinas/genética , Bacteriocinas/metabolismo , Lactococcus lactis/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/farmacologia
9.
J Microbiol ; 52(7): 604-8, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24972810

RESUMO

We constructed a H. pylori expression vector which consisted of both a His-tag and a GST tag as purification tools for recombinant protein and a chloramphenicol resistant cat gene as a reporter. The backbone of the vector pBK contained an ColEI origin of replication and a kanamycin resistant gene. A set of oligos for the His-tag and the PCR product of gst (glutathione S-transferase) gene were inserted sequentially in frame in the multi-cloning site of pBK. The orf of cat was inserted downstream of the gst to generate pBKHGC. The 3' part of H. pylori clpB and flaA were cloned into the vector which was introduced into H. pylori. Recombinant proteins were purified by GSH affinity column, digested with thrombin and were analyzed by western blotting. The final recombinant proteins were successfully purified.


Assuntos
Expressão Gênica , Vetores Genéticos , Helicobacter pylori/genética , Proteínas Recombinantes de Fusão/isolamento & purificação , Antibacterianos/farmacologia , Plasmídeos de Bacteriocinas/genética , Cromatografia de Afinidade/métodos , Clonagem Molecular/métodos , Farmacorresistência Bacteriana , Helicobacter pylori/metabolismo , Canamicina/farmacologia , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Origem de Replicação , Seleção Genética
10.
Am J Physiol Endocrinol Metab ; 305(1): E78-88, 2013 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-23651844

RESUMO

Blood glucose concentration is tightly regulated by the rate of insulin secretion and clearance, a process partially controlled by sensory neurons serving as metabolic sensors in relevant tissues. The activity of these neurons is regulated by the products of metabolism which regulate transmitter release, and recent evidence suggests that neuronally expressed ion channels of the transient receptor potential (TRP) family function in this critical process. Here, we report the novel finding that the cold and menthol-gated channel TRPM8 is necessary for proper insulin homeostasis. Mice lacking TRPM8 respond normally to a glucose challenge while exhibiting prolonged hypoglycemia in response to insulin. Additionally, Trpm8-/- mice have increased rates of insulin clearance compared with wild-type animals and increased expression of insulin-degrading enzyme in the liver. TRPM8 channels are not expressed in the liver, but TRPM8-expressing sensory afferents innervate the hepatic portal vein, suggesting a TRPM8-mediated neuronal control of liver insulin clearance. These results demonstrate that TRPM8 is a novel regulator of serum insulin and support the role of sensory innervation in metabolic homeostasis.


Assuntos
Glicemia/metabolismo , Hipoglicemia/genética , Insulina/metabolismo , Células Receptoras Sensoriais/metabolismo , Canais de Cátion TRPM/genética , Animais , Plasmídeos de Bacteriocinas , Diabetes Mellitus Experimental/metabolismo , Homeostase/fisiologia , Hipoglicemia/metabolismo , Células Secretoras de Insulina/metabolismo , Fígado/irrigação sanguínea , Fígado/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Veia Porta/inervação , Ratos , Canais de Cátion TRPM/metabolismo
11.
J Dairy Sci ; 96(1): 101-4, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23127914

RESUMO

The severity of Listeria monocytogenes infections emphasizes the need for prevention or elimination of the pathogen from dairy products. Lactococcus lactis KC24, isolated from kimchi, exhibited an antimicrobial effect against food pathogens, including L. monocytogenes ATCC 15313. Lactococcus lactis KC24 was cultured in a 5-L jar fermenter at 35°C, and bacteriocin activity was maximal at 4 h of incubation and persisted for 20 h. Bacteriocin KC24 was inactivated by protease XIV, indicating that it has a proteinaceous nature. Bacteriocin activity was maintained at pH 3.0 to 9.0 and at temperatures of 50 to 121°C. The mode of inhibition against L. monocytogenes ATCC 15313 was shown to involve a bactericidal effect by treatment with 100 and 200 arbitrary units (AU)/mL of bacteriocin KC24. To test the activity of bacteriocin KC24 in a food product, bacteriocin KC24 and nisin (100 and 200 AU/mL) with 4 log cfu/mL of a mixed culture of L. monocytogenes (ATCC 15313, ScottA, H7962, and H7762) were applied to UHT milk. Compared with the control, treatment with bacteriocin KC24 completely inhibited the growth of L. monocytogenes and resulted in no detectable L. monocytogenes after 14 d at 4°C, whereas nisin moderately inhibited L. monocytogenes, resulting in a final concentration after 14 d at 4°C higher than the initial inoculum. Bacteriocin KC24 may prove useful in improving the safety of dairy products.


Assuntos
Plasmídeos de Bacteriocinas/biossíntese , Lactococcus lactis/metabolismo , Listeria monocytogenes/efeitos dos fármacos , Leite/microbiologia , Animais , Anti-Infecciosos/metabolismo , Anti-Infecciosos/farmacologia , Fermentação , Microbiologia de Alimentos , Leite/química
12.
Braz. j. microbiol ; 43(4): 1452-1462, Oct.-Dec. 2012. graf, tab
Artigo em Inglês | LILACS | ID: lil-665832

RESUMO

A bacteriocin-like inhibitory substance producing Lactococcus lactis subsp lactis strain, ST1, isolated from goat milk of Iranian origin and with broad spectrum of activity and desirable technical properties was used for evaluating some futures of bacteriocin inhibitory activity. Cell growth and bacteriocin production studies were carried out in MRS medium incubated statically under uncontrolled pH condition. The antibacterial activity presented a primary metabolite pattern and showed a rapid decrease at the stationary phase. Microaerobiosis and capnophily growth conditions resulted in higher bacteriocin production while aerobiosis showed negative effect on both cell growth and bacteriocin production. Bacteriocin production, on the other hand, was favored in MRS broth (pH; 6.5) inoculated with 0.1 ml l-1 fresh culture when incubation was carried out at 30 °C. This indicated that the conditions resulted in higher levels of growth were frequently favoring bacteriocin production by ST1 as well. Decrease in activity, at the stationary growth phase, was much pronounced in favored growth condition. Nutrient depletion, deferent effect of low pH on bacteriocin production and/or protein degradation seemed more responsible for this phenomenon. The study also provided further data on new method for bacteriocin release from the cell wall of producer. It was clearly shown that both heating and ultrasound shock for 5 min at pH 2 could increase bacteriocin activity significantly. The release was more pronounced in the presence of 0.5% Tween80.


Assuntos
Antibacterianos/análise , Bacteriocinas/análise , Bacteriocinas/isolamento & purificação , Lactobacillus/isolamento & purificação , Leite , Plasmídeos de Bacteriocinas/análise , Plasmídeos de Bacteriocinas/isolamento & purificação , Ultrassom , Meio Ambiente , Amostras de Alimentos , Cabras , Métodos
13.
BMC Microbiol ; 12: 115, 2012 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-22720670

RESUMO

BACKGROUND: The sequenced O45:K1:H7 Escherichia coli meningitis strain S88 harbors a large virulence plasmid. To identify possible genetic determinants of pS88 virulence, we examined the transcriptomes of 88 plasmidic ORFs corresponding to known and putative virulence genes, and 35 ORFs of unknown function. RESULTS: Quantification of plasmidic transcripts was obtained by quantitative real-time reverse transcription of extracted RNA, normalized on three housekeeping genes. The transcriptome of E. coli strain S88 grown in human serum and urine ex vivo were compared to that obtained during growth in Luria Bertani broth, with and without iron depletion. We also analyzed the transcriptome of a pS88-like plasmid recovered from a neonate with urinary tract infection. The transcriptome obtained after ex vivo growth in serum and urine was very similar to those obtained in iron-depleted LB broth. Genes encoding iron acquisition systems were strongly upregulated. ShiF and ORF 123, two ORFs encoding protein with hypothetical function and physically linked to aerobactin and salmochelin loci, respectively, were also highly expressed in iron-depleted conditions and may correspond to ancillary iron acquisition genes. Four ORFs were induced ex vivo, independently of the iron concentration. Other putative virulence genes such as iss, etsC, ompTp and hlyF were not upregulated in any of the conditions studied. Transcriptome analysis of the pS88-like plasmid recovered in vivo showed a similar pattern of induction but at much higher levels. CONCLUSION: We identify new pS88 genes potentially involved in the growth of E. coli meningitis strain S88 in human serum and urine.


Assuntos
Plasmídeos de Bacteriocinas , Escherichia coli/crescimento & desenvolvimento , Escherichia coli/genética , Regulação Bacteriana da Expressão Gênica , Soro/microbiologia , Transcriptoma , Urina/microbiologia , Pré-Escolar , Proteínas de Escherichia coli/biossíntese , Perfilação da Expressão Gênica , Humanos , Lactente , Transcrição Genética , Fatores de Virulência/biossíntese
14.
PLoS One ; 7(3): e31413, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22403614

RESUMO

In 2006, a severe foodborne EHEC outbreak occured in Norway. Seventeen cases were recorded and the HUS frequency was 60%. The causative strain, Esherichia coli O103:H25, is considered to be particularly virulent. Sequencing of the outbreak strain revealed resemblance to the 2011 German outbreak strain E. coli O104:H4, both in genome and Shiga toxin 2-encoding (Stx2) phage sequence. The nucleotide identity between the Stx2 phages from the Norwegian and German outbreak strains was 90%. During the 2006 outbreak, stx(2)-positive O103:H25 E. coli was isolated from two patients. All the other outbreak associated isolates, including all food isolates, were stx-negative, and carried a different phage replacing the Stx2 phage. This phage was of similar size to the Stx2 phage, but had a distinctive early phage region and no stx gene. The sequence of the early region of this phage was not retrieved from the bacterial host genome, and the origin of the phage is unknown. The contaminated food most likely contained a mixture of E. coli O103:H25 cells with either one of the phages.


Assuntos
Surtos de Doenças , Infecções por Escherichia coli/epidemiologia , Escherichia coli/classificação , Escherichia coli/patogenicidade , Plasmídeos de Bacteriocinas/genética , Bacteriófagos/genética , Clonagem Molecular , DNA Viral/genética , Escherichia coli/genética , Escherichia coli/virologia , Infecções por Escherichia coli/microbiologia , Genoma Bacteriano/genética , Alemanha/epidemiologia , Dados de Sequência Molecular , Noruega/epidemiologia , Filogenia , Toxina Shiga II/genética
15.
Am J Emerg Med ; 30(8): 1385-8, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22217819

RESUMO

OBJECTIVE: Mild therapeutic hypothermia has been shown to improve neurologic outcomes after sudden cardiac arrest. Therapeutic hypothermia should be started as soon as return of spontaneous circulation occurs. However, saline is difficult to keep chilled in the prehospital environment. We sought to determine whether a cooler and ice packs could keep saline cold under prehospital conditions. METHODS: In phase 1 of the experiment, two 1000-mL bags of prechilled 0.9% normal saline were placed in a cooler with 3 ice packs. An additional bag of 1000-mL 0.9% normal saline remained outside the cooler as a control. Over 9 consecutive days, we measured the ambient air temperature and the temperature of each bag of saline every 4 hours. In phase 2 of the experiment, the cooler was kept sealed, and the temperature of the saline was measured after 24 hours. RESULTS: The mean temperatures over 24 hours ranged as follows: ambient temperature, 24°C to 27.2°C; bottom bag, 0.6°C to 3.5°C; top bag, 1.4°C to 5.7°C; and control bag, 9.8°C to 26.8°C. A t test was used to compare the chilled saline against the control bag. Statistical significance (P < .05) was achieved at all times. In phase 2 of the experiment, after 24 hours, 100% of the bottom bags and 93% of the top bags were less than 6°C. CONCLUSIONS: Our data demonstrate that saline can be kept chilled in ambulances for 24 hours using ice packs and coolers. The estimated cost is less than $50.00 per ambulance. Using coolers and ice packs is an inexpensive way for emergency medical service agencies to initiate prehospital hypothermia.


Assuntos
Serviços Médicos de Emergência/métodos , Refrigeração/métodos , Cloreto de Sódio , Ambulâncias , Plasmídeos de Bacteriocinas , Fatores de Tempo
16.
Proc Natl Acad Sci U S A ; 109(4): 1269-74, 2012 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-22232693

RESUMO

The mammalian gut harbors a dense microbial community interacting in multiple ways, including horizontal gene transfer (HGT). Pangenome analyses established particularly high levels of genetic flux between Gram-negative Enterobacteriaceae. However, the mechanisms fostering intraenterobacterial HGT are incompletely understood. Using a mouse colitis model, we found that Salmonella-inflicted enteropathy elicits parallel blooms of the pathogen and of resident commensal Escherichia coli. These blooms boosted conjugative HGT of the colicin-plasmid p2 from Salmonella enterica serovar Typhimurium to E. coli. Transconjugation efficiencies of ~100% in vivo were attributable to high intrinsic p2-transfer rates. Plasmid-encoded fitness benefits contributed little. Under normal conditions, HGT was blocked by the commensal microbiota inhibiting contact-dependent conjugation between Enterobacteriaceae. Our data show that pathogen-driven inflammatory responses in the gut can generate transient enterobacterial blooms in which conjugative transfer occurs at unprecedented rates. These blooms may favor reassortment of plasmid-encoded genes between pathogens and commensals fostering the spread of fitness-, virulence-, and antibiotic-resistance determinants.


Assuntos
Evolução Biológica , Colite/microbiologia , Enterobacteriaceae/genética , Transferência Genética Horizontal/genética , Animais , Plasmídeos de Bacteriocinas/genética , Sequência de Bases , Biologia Computacional , Primers do DNA/genética , Enterobacteriaceae/crescimento & desenvolvimento , Escherichia coli/genética , Camundongos , Dados de Sequência Molecular , Análise de Sequência com Séries de Oligonucleotídeos , Filogenia , RNA Ribossômico 16S/genética , Salmonella typhimurium/genética , Alinhamento de Sequência , Análise de Sequência de DNA
18.
Curr Protein Pept Sci ; 13(3): 193-204, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-21827422

RESUMO

The continuing problem of the emergence of multidrug resistance in pathogens has resulted in renewed efforts to identify novel antimicrobials that could be used in clinical settings. Lantibiotics are bacterially produced gene encoded antimicrobial peptides which have been the focus of extensive investigation in recent years because of their broad spectrum of activity. Lantibiotics (lanthionine-containing antibiotics), which have traditionally been regarded as antimicrobials for use in food or veterinary medicine, may provide at least part of the solution to these problems. Lacticin 3147 is a two peptide lantibiotic (consisting of the peptides Ltnα and Ltnß) which is active at low concentrations against many pathogens. It has been the subject of extensive research, which has generated significant insights into the mechanisms of lacticin 3147 biosynthesis, immunity, structure function relationships and the consequences of molecular bioengineering. The merits of employing lacticin 3147 to control spoilage microbes as well as its potential in the elimination of food, human and veterinary pathogens have also been highlighted. Here we review the knowledge which has been gained with respect to lacticin 3147 since its discovery in 1995.


Assuntos
Antibacterianos/biossíntese , Bacteriocinas/biossíntese , Sequência de Aminoácidos , Animais , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Plasmídeos de Bacteriocinas , Bacteriocinas/genética , Bacteriocinas/farmacologia , Bacteriocinas/uso terapêutico , Resistencia a Medicamentos Antineoplásicos , Microbiologia de Alimentos , Conservação de Alimentos , Humanos , Viabilidade Microbiana/genética , Dados de Sequência Molecular , Engenharia de Proteínas , Medicina Veterinária
19.
Foodborne Pathog Dis ; 8(8): 843-52, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21495855

RESUMO

The foodborne transmission of Listeria monocytogenes requires physiological adaptation to various conditions, including the cold, osmotic, heat, acid, alkaline, and oxidative stresses, associated with food hygiene, processing, and preservation measures. We review the current knowledge on the molecular stress adaptation responses in L. monocytogenes cells as revealed through transcriptome, proteome, genetic, and physiological analysis. The adaptation of L. monocytogenes to stress exposure is achieved through global expression changes in a large number of cellular components. In addition, the cross-protection of L. monocytogenes exposed to different stress environments might be conferred through various cellular machineries that seem to be commonly activated by the different stresses. To assist in designing L. monocytogenes mitigation strategies for ready-to-eat food products, further experiments are warranted to specifically evaluate the effects of food composition, additives, preservatives, and processing technologies on the modulation of L. monocytogenes cellular components in response to specific stresses.


Assuntos
Perfilação da Expressão Gênica , Listeria monocytogenes/fisiologia , Proteômica , Estresse Fisiológico/genética , Estresse Fisiológico/fisiologia , Adaptação Fisiológica , Plasmídeos de Bacteriocinas , Doenças Transmitidas por Alimentos/microbiologia , Doenças Transmitidas por Alimentos/prevenção & controle , Temperatura Alta , Concentração de Íons de Hidrogênio , Listeria monocytogenes/genética , Listeriose , Concentração Osmolar , Estresse Oxidativo
20.
J Dairy Sci ; 94(3): 1146-54, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21338780

RESUMO

Colicin E2 (ColE2) is a proteinaceous bacterial toxin produced by some strains of Escherichia coli and other members of the Enterobacteriaceae that exhibits inhibitory activity against some strains of E. coli O157:H7. A 2.0-kb DNA fragment, containing the ColE2 structural gene ceaB and immunity gene ceiB from E. coli NCTC 50133 (pColE2-P9), was cloned into the lactococcal plasmid vector pNZ2103. The lysis gene, celB, was not cloned. The plasmid, pLR-E2, encoding the cloned genes was transformed into E. coli DH5α and Lactococcus lactis ssp. lactis LM0230 and PN-1 using electroporation. The bacteriocin ColE2 was expressed in transformants of both E. coli and L. lactis ssp. lactis. Secretion of ColE2 into media was verified by spot-on-lawn assays and measurement of ColE2 activity in the growth medium of transformants. The level of ColE2 produced by transformants containing pLR-E2 was similar to that produced by the parental strain, E. coli NCTC 50133 (pColE2-P9). Evaluation of a ColE2-producing transformant of L. lactis ssp. lactis as a starter culture revealed that, although ColE2 was produced by transformants and could be detected in milk during fermentation, the inhibitory activity of ColE2 against E. coli O157:H7 was significantly decreased in milk compared with buffered growth medium.


Assuntos
Colicinas/genética , Escherichia coli O157/metabolismo , Lactococcus lactis/genética , Animais , Plasmídeos de Bacteriocinas/genética , Clonagem Molecular , Fermentação , Leite/microbiologia
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