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1.

Azurin is a novel anticancer protein, mainly produced from Pseudomonas aeruginosa and few other Gram-negative bacteria. In this study, azurin gene (azu) from a native Pseudomonas aeruginosa strain SSj was amplified using PCR with specific primers. The azurin gene (418 bp) was sequenced and submitted in Genbank. The PCR amplicon was digested with BamHI and HindIII and inserted into expression vector pET-22b(+). The recombinant protein was expressed in Escherichia coli BL21 (DE3) after induction with IPTG. Protein purification was done using Ni NTA agarose. The SDS-PAGE analysis of purified samples with Coomassie brilliant blue showed a band with an apparent molecular weight of about 14 kDa. Structural characterization of purified protein was done by FTIR, MALDI-TOF and LC–MS/MS analysis.

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2.
The purpose of this study was to determine the inhibitory effects of cranberry juice on pathogenic microorganisms. The microorganisms analyzed were Escherichia coli from patients with urinary infections, Salmonella spp., Listeria monocytogenes, Pseudomona aeruginosa, and Staphylococcus aureus. The disc method was used to determine the sensitivity of bacteria to cranberry juice (CJ, both concentrated and diluted). A lawn of 106 cfu/ml was grown on agar surfaces in Petri dishes and on Whatman discs that had been previously saturated with CJ and CJ : water. 1 : 1 to 1 : 50 juice solutions had been placed on the discs, which were cultured and incubated. The results indicated that S. aureus was more susceptible to cranberry juice inhibition than the other microorganisms. L. monocytogenes was the most resistant to the inhibitory action of cranberry juice, showing a significant difference from the inhibition of P. aeruginosa, uropathogenic E. coli, Salmonella spp., and S. aureus. This study also demonstrated that the inhibitory activity of cranberry juice for E. coli took place up to a dilution of 1 : 20. Published in Russian in Prikladnaya Biokhimiya i Mikrobiologiya, 2008, Vol. 44, No. 3, pp. 333–336. The text was submitted by the authors in English.  相似文献   

3.
Carvacrol has been recognized as an efficient growth inhibitor of food pathogens. However, carvacrol oil is poorly water-soluble and can be oxidized, decomposed or evaporated when exposed to the air, light, or heat. To overcome these limitations, a carvacrol nanoemulsion was developed and its antimicrobial activity against food pathogens evaluated in this study. The nanoemulsion containing 3% carvacrol oil, 9% surfactants (HLB 11) and 88% water, presented good stability over a period of 90 days. In general, the carvacrol nanoemulsion (MIC: 256 µg ml−1 for E. coli and Salmonella spp., 128 µg ml−1 for Staphylococcus aureus and Pseudomonas aeruginosa) exhibited improved antimicrobial activity compared to the free oil. The carvacrol nanoemulsion additionally displayed bactericidal activity against Escherichia coli, P. aeruginosa and Salmonella spp. Therefore, the results of this study indicated that carvacrol oil nanoemulsions can potentially be incorporated into food formulations, wherein their efficacy for the prevention and control of microbial growth could be evaluated.  相似文献   

4.
Abstract

In this study, azurin, a bacteriocin with anticancer property, was produced by food-grade Lactococcus lactis using the Nisin Controlled Gene Expression (NICE) System. In addition, the antibacterial and cytotoxic properties of recombinant azurin in the culture supernatant were also investigated. Azurin gene from Pseudomonas aeruginosa was cloned into the pNZ8149 vector and the resulting recombinant DNA was transformed into food grade L. lactis NZ3900. The expression of azurin protein was induced by the optimum concentration of nisin for 3?h. Inhibition zones for Escherichia coli and Bacillus cereus were observed at 5.0 and 10?mg/mL concentrations of lyophilized supernatants containing azurin, but no inhibition zone at azurin-free lyophilized supernatants. When HUVEC, HT29, HCT116, and MCF7 cell lines were treated with lyophilized culture supernatants with azurin or without azurin, cell viability decreased with increasing concentrations of the supernatant. Furthermore, the supernatants containing azurin showed more anti-proliferative effect than the azurin-free supernatants. This work provides a practicable method to produce recombinant azurin in the food grade L. lactis strain. As a result, the recombinant L. lactis strain, producing azurin, can be used in the investigation of food biopreservatives and in the development of a therapeutic probiotic.  相似文献   

5.
Azurin is a bacterial protein from Pseudomonas aeruginosa which exerts an inhibitory activity in cancer cells. In P-cadherin-overexpressing models, a bad prognosis marker in breast cancer increasing invasion and other malignant features, azurin decreases the invasion of cancer cells.We performed a microarray analysis to compare the expression profile of azurin treated cells with different P-cadherin expression levels. Azurin up-regulated apoptosis mediated by p53 protein, endocytosis and vesicle-mediated transport. In the contrary, in invasive MCF-7/AZ.Pcad cells, azurin decreased the expression of genes associated with cell surface receptors and signal transduction, as well as biological adhesion. Further, azurin decreased adhesion of cells to proteins from the extracellular matrix (ECM) and altered protein expression of integrins α6, β4 and β1 and interfered with the ability of these cells to form mammospheres. Altogether, our results further enlighten the anti-cancer effects mediated by azurin in P-cadherin overexpression breast cancer models.  相似文献   

6.
In an epidemiological survey of human enterobacterial infections in the Republic of Korea during three years from 2004 to 2006, we isolated 1,784 (6.2%, isolation rate of enteropathogens from stool samples) in 2004, 2,547 (9.5%) in 2005 and 3,506 bacteria (12.3%) from people who visited clinics. Among the isolated bacteria, pathogenic Escherichia coli, especially, EAEC was the most frequently identified pathogen in both urban and rural regions followed by Staphylococcus aureus, Salmonella species, Bacillus cereus, Vibrio parahaemolyticus, Campylobacter jejuni, Clostridium perfringens, and Shigella species. Distinct seasonality was found in V. parahaemolyticus species, while this pathogen showed no age-specific patterns. However, other bacteria, i.e., pathogenic E. coli, S. aureus, Salmonella spp., and B. cereus showed similar seasonality throughout the year, showing a slight increase in the infection rate during the summer months and high prevalence among children under 10 years of age and elder-age people. The antibiotic susceptibility patterns of pathogenic E. coli, Salmonella spp., and S. aureus showed high resistance to penicillins. However, both pathogenic E. coli and Salmonella spp. were susceptible to several cephems, imipenem, and amikacin. Moreover, S. aureus strains resistant to vancomycin were not found. In conclusion, these surveillances can play an important role for the control and prevention to the diseases originated by enteritis bacteria.  相似文献   

7.
Enteroinvasive Escherichia coli (EIEC), heat-labile enterotoxin (LT) E. coli, Shigella spp., and Salmonella spp. are common enteric pathogens, which cause food-borne diseases if consumed in contaminated milk products. The rapid and reliable methods for detecting are imperative for reduction in hazard of infection. In this study, we selected primers, optimized the polymerase chain reaction (PCR) conditions, and analyzed the sensitivity and specificity of the multiplex PCR assay to screen raw milk from these enteric bacteria. Furthermore, EIEC, LT-E. coli, Shigella spp., Salmonella spp., and 11 non-targeted pathogenic strains were performed for the specificity of the multiplex PCR. Specific bands showed in EIEC, LT-E. coli, Shigella spp., and Salmonella spp. but no bands showed in other 11 pathogenic strains. The sensitivity of multiplex PCR was relatively high, was rounded to 200 CFU/ml (Shigella spp. and EIEC), 320 CFU/ml (Salmonella spp.), and 100 CFU/ml (LT-E. coli). This method for simultaneous and rapid detection of enteric pathogens (EIEC, LT-E. coli, Shigella spp., and Salmonella spp.) in raw milk showed high sensitivity and specificity, and led to faster track to report results.  相似文献   

8.
Attachment tendencies of Escherichia coli K12, Pseudomonas aeruginosa ATCC 9027, and Staphylococcus aureus CIP 68.5 onto glass surfaces of different degrees of nanometer-scale roughness have been studied. Contact-angle and surface-charge measurements, atomic force microscopy (AFM), scanning electron microscopy (SEM), and confocal laser scanning microscopy (CLSM) were employed to characterize substrata and bacterial surfaces. Modification of the glass surface resulted in nanometer-scale changes in the surface topography, whereas the physicochemical characteristics of the surfaces remained almost constant. AFM analysis indicated that the overall surface roughness parameters were reduced by 60–70%. SEM, CLSM, and AFM analysis clearly demonstrates that although E. coli, P. aeruginosa and S. aureus present significantly different patterns of attachment, all of the species exhibited a greater propensity for adhesion to the “nano-smooth” surface. The bacteria responded to the surface modification with a remarkable change in cellular metabolic activity, as shown by the characteristic cell morphologies, production of extracellular polymeric substances, and an increase in the number of bacterial cells undergoing attachment.  相似文献   

9.
A multiplex PCR and DNA array for quick detection of Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella spp. was developed using specific genetic markers derived from virulence-related genes. The genetic markers of cytK, sei, prfA, rfB, and hilA gene specifically amplified DNA fragments of 320 bp, 500 bp, 700 bp, 1.0 kb and 1.2 kb from B. cereus, S. aureus, L. monocytogenes, E. coli O157:H7, and Salmonella spp., respectively. These markers are specific for the detection of the corresponding target pathogens. The sensitivity of the genetic markers was down to ~0.5 fg genomic DNA and ~101 CFU/ml (one bacterial cell per reaction) of bacterial culture. The combination of mPCR and DNA macroarray hybridization sensitively and specifically detected B. cereus, S. aureus, L. monocytogenes, E. coli O157:H7, and Salmonella spp., in complex mixed cultures and food matrices. Thus, this mPCR and macroarray-based approach serves as rapid and reliable diagnostic tool for the detection of these five pathogens.  相似文献   

10.

Background

The probiotic Escherichia coli strain Nissle 1917 (EcN) has been shown to interfere in a human in vitro model with the invasion of several bacterial pathogens into epithelial cells, but the underlying molecular mechanisms are not known.

Methodology/Principal Findings

In this study, we investigated the inhibitory effects of EcN on Salmonella Typhimurium invasion of porcine intestinal epithelial cells, focusing on EcN effects on the various stages of Salmonella infection including intracellular and extracellular Salmonella growth rates, virulence gene regulation, and adhesion. We show that EcN affects the initial Salmonella invasion steps by modulating Salmonella virulence gene regulation and Salmonella SiiE-mediated adhesion, but not extra- and intracellular Salmonella growth. However, the inhibitory activity of EcN against Salmonella invasion always correlated with EcN adhesion capacities. EcN mutants defective in the expression of F1C fimbriae and flagellae were less adherent and less inhibitory toward Salmonella invasion. Another E. coli strain expressing F1C fimbriae was also adherent to IPEC-J2 cells, and was similarly inhibitory against Salmonella invasion like EcN.

Conclusions

We propose that EcN affects Salmonella adhesion through secretory components. This mechanism appears to be common to many E. coli strains, with strong adherence being a prerequisite for an effective reduction of SiiE-mediated Salmonella adhesion.  相似文献   

11.
Black soldier fly (BSF) larvae are considered a promising biological reactor to convert organic waste and reduce the impact of zoonotic pathogens on the environment. We analysed the effects of BSF larvae on Staphylococcus aureus and Salmonella spp. populations in pig manure (PM), which showed that BSF larvae can significantly reduce the counts of the associated S. aureus and Salmonella spp. Then, using a sterile BSF larval system, we validated the function of BSF larval intestinal microbiota in vivo to suppress pathogens, and lastly, we isolated eight bacterial strains from the BSF larval gut that inhibit S. aureus. Results indicated that functional microbes are essential for BSF larvae to antagonise S. aureus. Moreover, the analysis results of the relationship between the intestinal microbiota and S. aureus and Salmonella spp. showed that Myroides, Tissierella, Oblitimonas, Paenalcalignes, Terrisporobacter, Clostridium, Fastidiosipila, Pseudomonas, Ignatzschineria, Savagea, Moheibacter and Sphingobacterium were negatively correlated with S. aureus and Salmonella. Overall, these results suggested that the potential ability of BSF larvae to inhibit S. aureus and Salmonella spp. present in PM is accomplished primarily by gut-associated microorganisms.  相似文献   

12.
P-cadherin overexpression occurs in about 30% of all breast carcinomas, being a poor prognostic factor for breast cancer patients. In a cellular background of wild-type E-cadherin, we have previously shown that its expression promotes invasion, motility and migration of breast cancer cells due to the induced secretion of metalloproteases (MMPs) to the extracellular medium and to the concomitant shedding of a pro-invasive soluble form of this protein (sP-cad). Azurin is secreted by Pseudomonas aeruginosa and induces in vitro and in vivo cytotoxicity after its preferential penetration in human cancer cells relative to normal cells. Three different breast cancer cell lines, MCF-7/AZ.Mock, MCF-7/AZ.Pcad and SUM149 were treated with sub-killing doses of azurin. Invasion of these cells was measured using Matrigel Invasion Assays and MTT assays were performed to determine cell viability upon treatment and the effects on cadherins expression was determined by Western blot and Immunofluorescence. Gelatin Zymography was used to determine activity of MMP2 in the conditioned media of azurin treated and untreated cells and the phosphorylation levels of intracellular signaling proteins were determined by Western blot. The invasive phenotype of these breast cancer cells was significantly reduced by azurin. Azurin (50–100 µM) also caused a specific decrease on P-cadherin protein levels from 30–50% in MCF-7/AZ.Pcad and SUM149 breast cancer cell lines, but the levels of E-cadherin remain unaltered. More, the levels of sP-cad and the activity of MMP2 were reduced in the extracellular media of azurin treated cells and we also observed a decrease in the phosphorylation levels of both FAK and Src proteins. Our data show that azurin specifically targets P-cadherin, not E-cadherin, abrogating P-cadherin-mediated invasive effects and signaling. Therefore, azurin could possibly be considered a therapeutic tool to treat poor-prognosis breast carcinomas overexpressing P-cadherin in a wild type E-cadherin context.  相似文献   

13.
Biofilms pose a serious public health hazard with a significant economic impact on the food industry. The present scoping review is designed to analyse the literature published during 2001–2020 on biofilm formation of microbes, their detection methods, and association with antimicrobial resistance (if any). The peer-reviewed articles retrieved from 04 electronic databases were assessed using PRISMA-ScR guidelines. From the 978 preliminary search results, a total of 88 publications were included in the study. On analysis, the commonly isolated pathogens were Listeria monocytogenes, Staphylococcus aureus, Salmonella spp., Escherichia coli, Bacillus spp., Vibrio spp., Campylobacter jejuni and Clostridium perfringens. The biofilm-forming ability of microbes was found to be influenced by various factors such as attachment surfaces, temperature, presence of other species, nutrient availability etc. A total of 18 studies characterized the biofilm-forming genes, particularly for S. aureus, Salmonella spp., and E. coli. In most studies, polystyrene plate and/or stainless-steel coupons were used for biofilm formation, and the detection was carried out by crystal violet assays and/or by plate counting method. The strain-specific significant differences in biofilm formation were observed in many studies, and few studies carried out analysis of multi-species biofilms. The association between biofilm formation and antimicrobial resistance was not clearly defined. Further, viable but non-culturable form of the foodborne pathogens is posing an unseen (by conventional cultivation techniques) but potent threat to the food safety. The present review recommends the need for carrying out systematic surveys and risk analysis of biofilms in food chain to highlight the evidence-based public health concerns, especially in regions where microbiological food hazards are quite prevalent.  相似文献   

14.
Interspecific interaction happens frequently among bacterial species and can promote the colonization of polymicrobial community in various environments. However, it is not clear whether the intervention of antibiotics, which is a common therapeutic method for infectious disease, will influence the interacting dynamics of different pathogenic bacteria. By using the frequently co-isolated bacteria Pseudomonas aeruginosa and Staphylococcus aureus as models, here we identify an antibiotic-determined mutual invasion relationship between bacterial pathogens. We show that although P. aeruginosa has a significant intrinsic competitive advantage over S. aureus by producing the quorum-sensing (QS)-controlled anti-staphylococcal molecules, methicillin-resistant S. aureus (MRSA) can inhibit neighbouring P. aeruginosa in the presence of subinhibitory aminoglycoside antibiotics (e.g. streptomycin) to P. aeruginosa. Importantly, subinhibitory streptomycin decreases the expression of QS-regulated genes in P. aeruginosa and thus relieves the survival stress of MRSA brought by P. aeruginosa. On the other side, the iron-uptake systems and pathogenicity of MRSA can be enhanced by the extracellular products of streptomycin-treated P. aeruginosa. Therefore, this study provides an explanation for the substitution of dominant species and persistent coexistence of bacterial pathogens in the host with repeated antibiotic therapies and contributes to further understanding the pathogenesis of chronic polymicrobial infections.  相似文献   

15.
Azurin secreted by Pseudomonas aeruginosa is an anticancer bacteriocin, which preferentially enters human cancer cells and induces apoptosis or growth inhibition. It turns out that azurin is a multi‐target anticancer agent interfering in the p53 signaling pathway and the non‐receptor tyrosine kinases signaling pathway. This suggests that azurin exerts its anticancer activity by interacting with multiple targets and interfering in multiple steps in disease progression. Therefore, azurin could overcome resistance to therapy. Besides azurin, putative bacteriocins that possess functional properties similar to those of azurin have been identified in more bacteria species. A systematic investigation on the anticancer mechanisms of azurin and the azurin‐like bacteriocins will provide more and better options in cancer therapy. In this review, we summarize how azurin and the derived peptides hijack key cellular regulators or cell surface receptors to remodel the cellular signaling networks. In particular, we highlight the necessity of determining the structure of azurin/p53 complex and investigating the influence of post‐translational modifications on interactions between azurin and p53. Therapeutic applications of azurin and derived peptides are also discussed.  相似文献   

16.
Ice used for direct human consumption or to preserve foods and cool down drinks can be contaminated with pathogenic microorganisms and may potentially become a vehicle for consumer’s infection. To evaluate physical, chemical and microbiological quality of commercial ice and ice used for fish and seafood, 100 ice samples collected at 10 different retail points in the region of Epirus were studied. The following microbiological parameters were determined: Total coliforms, fecal coliforms, Salmonella spp., Shigella spp., Yersinia spp., Escherichia coli, Campylobacter sp., Vibrio cholerae, Aeromonas spp., Pseudomonas aeruginosa and Clostridium perfringens.E. coli was detected in 22% and coliforms were detected in 31% of samples. Samples in which coliforms were detected fail to meet the microbiological criteria specified by the drinking water legislation.Aeromonas spp., Shigella spp., Campylobacter sp. and V. cholerae were not detected. Spore forms of C. perfringens were prevalent at 35% and the psychotropic bacterium’s P. aeruginosa and Yersinia spp. were found only at three samples each.The presence of large numbers of coliforms as well as of other pathogenic strains suggested that commercial ice and ice used to make cool drinks or in preservation of fish and seafood may represent a potential hazard to the consumer. In view of the results reported herein, it is highly recommended that national regulatory guidelines should be established for the production of ice as long as regular inspections.  相似文献   

17.
AKACID Plus, a novel polymeric guanidine with broad antimicrobial activity against multiantibiotic-resistant bacterial strains, was used in the present study as a room disinfectant. Disinfection of closed rooms experimentally contaminated with antibiotic-susceptible and multiresistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, and Escherichia coli was performed using AKACID Plus at concentrations of 0.1, 0.25, and 0.5% for 100 min. Bacterial suspensions were distributed on plastic and stainless steel plates and placed in a test room. Recovery of the test microorganisms was determined before nebulizing, 60 and 100 min after initiation, and 4 h after the end of room disinfection by a simple swab-rinse technique. The swab-rinse method demonstrated a dose- and time-dependent effectiveness of AKACID Plus in eradicating S. aureus, E. coli, and P. aeruginosa on plastic and stainless steel plates. Nebulized 0.5% AKACID Plus was successful in eliminating all hospital pathogens within 340 min. After the use of 0.25% AKACID Plus, MRSA was still detectable on microbial carrier plates. The test concentration of 0.1% AKACID Plus achieved a significant reduction of S. aureus and P. aeruginosa on plastic and stainless steel plates but was sufficient to eradicate only E. coli. These results suggest that nebulized AKACID Plus at a concentration of 0.5% is a potent substance for eradication of pathogenic organisms in the hospital setting.  相似文献   

18.
A new methodology for detecting the microbiological state of a wound dressing in terms of its colonization with pathogenic bacteria such as Staphylococcus aureus or Pseudomonas aeruginosa has been developed. Here we report how stabilized lipid vesicles containing self-quenched carboxyfluorescein dye are sensitive to lysis only by toxins/virulence factors from P. aeruginosa and S. aureus but not by a non-toxic Escherichia coli species. The development of the stabilized vesicles is discussed and their response to detergent (triton), bacterial toxin (α-hemolysin) and lipases (phospholipase A2). Finally, fabrics with stabilized vesicles attached via plasma deposited maleic anhydride coupling are shown visibly responding to S. aureus (MSSA 476) and P. aeruginosa (PAO1) but not E. coli DH5α in a prototype dressing.  相似文献   

19.
Pseudomonas aeruginosa outer membrane protein F was purified by extraction from polyacrylamide gels of cell envelope proteins of anEscherichia coli strain expressing the cloned gene for protein F. Antisera directed against protein F purified fromP. aeruginosa PAO1 reacted with thisE. coli strain by immunofluorescence assay and immunoblotting, whereas these antisera were nonreactive withE. coli strains lacking thePseudomonas protein F gene. The protein F purified from thisE. coli strain was used to immunize mice by intramuscular injection of 10 µg of protein F preparation on days 1 and 14, followed by burn and challenge of the mice on day 28. As compared with control mice immunized withE. coli K-12 lipopolysaccharide, immunization with theE. coli-derived protein F afforded significant protection against subsequent challenge with heterologous Fisher-Devlin immunotype 5 and 6 strains ofP. aeruginosa. Antisera from mice immunized with theE. coli-derived protein F reacted at bands corresponding to protein F and 2-mercaptoethanol-modified protein F upon immunoblotting against cell envelope proteins of the PAO1, immunotype 5, and immunotype 6 strains ofP. aeruginosa and theE. coli strain containing the cloned F gene, but failed to react at these sites in anE. coli strain lacking the F gene. These data demonstrate thatP. aeruginosa protein F produced inE. coli through genetic engineering techniques retains its vaccine efficacy in the complete absence of anyP. aeruginosa lipopolysaccharide.  相似文献   

20.
There is a wide range of factors affecting bacterial adhesion and biofilm formation. However, in both food processing and medical settings, it is very hard to obtain suitably controlled conditions so that the factors that reduce surface colonisation and biofouling can be studied. The aim of this study was to evaluate the effect of glucose concentration, temperature and stainless steel (SS) surface roughness on biofouling by four common pathogens (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and L. monocytogenes). Among the tested variables, the untreated SS surface (3C) was shown to be fouled more than 3D polished, brushed or electropolished SS surfaces. Although an array of parameters influenced biofouling, the most promising control measure was the influence of low temperature (4?°C) that reduced biofouling even in the case of the psychrophilic Listeria monocytogenes. The study findings could significantly contribute to the prevention of SS surface contamination and consequential biofouling by food and healthcare associated pathogens.  相似文献   

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