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1.
M. Shuhaimi B.M. Kabeir A.M. Yazid M. Nazrul Somchit 《Journal of applied microbiology》2009,106(1):191-198
Aims: This study demonstrated the optimum growth of Bifidobacterium pseudocatenulatum G4 with prebiotics via statistical model.
Methods and Results: Commercial prebiotics [inulin and fructooligosaccharide (FOS)], together with sorbitol, arabinan and inoculum rate, were tested by fractional factorial design to determine their impact on growth of Bif. pseudocatenulatum G4 in skim milk. At 48 h incubation, bacterial growth was mainly influenced by FOS and inoculum rate. Growth reduction was observed in all samples incubated for 72 h. Central composite design (CCD) was adopted using FOS and inoculum rate at 48 h incubation to develop the statistical model for optimization. The model predicted that 2·461 log CFU ml−1 produced the optimum growth increase of Bif. pseudocatenulatum G4. The combination that produced the optimum point was 2·86% FOS (g/v) and 0·67% inoculum rate (v/v).
Conclusion: At optimum combination of inoculum rate and FOS, validation experiments recorded 2·40 ± 10·02 log CFU ml−1 . The application in 1-l bioreactor for 24 h showed higher growth increase of 2·95 log CFU ml−1 .
Significant and Impact of the Study: Response surface methodology approach is useful to develop optimum synbiotics combination for strain G4 with FOS. 相似文献
Methods and Results: Commercial prebiotics [inulin and fructooligosaccharide (FOS)], together with sorbitol, arabinan and inoculum rate, were tested by fractional factorial design to determine their impact on growth of Bif. pseudocatenulatum G4 in skim milk. At 48 h incubation, bacterial growth was mainly influenced by FOS and inoculum rate. Growth reduction was observed in all samples incubated for 72 h. Central composite design (CCD) was adopted using FOS and inoculum rate at 48 h incubation to develop the statistical model for optimization. The model predicted that 2·461 log CFU ml
Conclusion: At optimum combination of inoculum rate and FOS, validation experiments recorded 2·40 ± 10·02 log CFU ml
Significant and Impact of the Study: Response surface methodology approach is useful to develop optimum synbiotics combination for strain G4 with FOS. 相似文献
2.
Many aspects of biodefense research require quantitative growth assessments of the test agent. This study evaluated the BioNanoPore (BNP™) technology to quantitate Bacillus anthracis and Yersinia pestis faster than traditional plate counting methods. The BNP™ technology enabled quantification of B. anthracis and Y. pestis in phosphate-buffered saline and naïve rabbit blood at 6 and 24 h, respectively. After 6 h of growth, counts for B. anthracis ranged from 6·19–6·45 log10 CFU ml−1 on BNP™, while counts after 24 h on tryptic soy agar (TSA) ranged from 6·51–6·58 log10 CFU ml−1 . For Y. pestis , counts on BNP™ at 24 h ranged from 6·31–6·41 log10 CFU ml−1 on BNP™ and ranged from 6·44–6·89 log10 CFU ml−1 on TSA at 48 h. This study demonstrates that the BNP™ technology provides a more rapid detection of B. anthracis and Y. pestis , which could aid in the evaluation of potential medical countermeasures and treatments as well as other biological defense applications such as surface sampling or decontamination efficacy. 相似文献
3.
Aims: Concentration of pathogens diluted in large volumes of water is necessary for their detection. An automated concentration system placed online in drinking water distribution systems would facilitate detection and mitigate the risk to public health.
Methods and Results: A prototype concentrator based on dead-end hollow fibre ultrafiltration was used to concentrate Bacillus atrophaeus spores directly from tap water. Backflush was used to recover accumulated particulates for analysis. In field tests conducted on a water utility distribution system, 3·2 × 104 –1·4 × 106 CFU ml−1 (6·1 × 106 –3·0 × 108 CFU) were recovered from the filter when 2·9 × 107 –1·0 × 109 CFU were spiked into the system. Per cent recovery ranged from 21% to 68% for flow volumes of 15–21 l. Tests using spore influent levels <10 CFU l−1 (spike < 1000 CFU) yielded 23–40% recovery for volumes >100 l.
Conclusions: B. atrophaeus spores at levels <10 CFU l−1 were concentrated directly from tap water using an automated dead-end hollow-fibre ultrafiltration system.
Significance and Impact of the Study: The prototype concentrator represents a critical step towards an autonomous system that could be installed in drinking water distribution lines or other critical water lines to facilitate monitoring. Recovered samples can be analysed using standard or rapid biosensor methods. 相似文献
Methods and Results: A prototype concentrator based on dead-end hollow fibre ultrafiltration was used to concentrate Bacillus atrophaeus spores directly from tap water. Backflush was used to recover accumulated particulates for analysis. In field tests conducted on a water utility distribution system, 3·2 × 10
Conclusions: B. atrophaeus spores at levels <10 CFU l
Significance and Impact of the Study: The prototype concentrator represents a critical step towards an autonomous system that could be installed in drinking water distribution lines or other critical water lines to facilitate monitoring. Recovered samples can be analysed using standard or rapid biosensor methods. 相似文献
4.
Detection of infectious rotavirus in naturally contaminated source waters for drinking water production 总被引:1,自引:0,他引:1
S.A. Rutjes W.J. Lodder A. Docters van Leeuwen A.M. de Roda Husman 《Journal of applied microbiology》2009,107(1):97-105
Aims: To assess chlorine susceptibility of Legionella pneumophila grown from two amoebic hosts, Acanthamoeba castellanii and Hartmannella vermiformis .
Methods and Results: After being released from amoebae, Leg. pneumophila were chlorinated at 2 and 5 mg l−1 for 5 min–24 h. Bacterial culturability and cytoplasmic membrane deterioration were quantified by culture assay on BCYEα agar and BacLight stains coupled with a fluorescent microscope, respectively. Chlorination reduced the culturability of Leg. pneumophila by 2·93–4·59 log CFU ml−1 and damaged cellular membrane by 53·8–99·2%. Moreover, cells released from H. vermiformis exhibited significantly lower degrees in culturability reduction ( P = 0·0008) and membrane deterioration ( P < 0·0001) when compared with those from A. castellanii . The amoebic genus is the most significant parameter affecting cytoplasmic membrane integrity of chlorinated Legionella ( P < 0·0001), followed by free chlorine concentration ( P = 0·042).
Conclusions: Legionella pneumophila replicated from H. vermiformis possess greater chlorine resistance than the cells from A. castellanii .
Significance and Impact of the Study: This study shows the heterogeneity of amoebae-grown Leg. pneumophila in chlorine susceptibility, which should be considered in the control of legionellae proliferation, particularly in the systems where H. vermiformis is dominant, e.g. hot water plumbing. 相似文献
Methods and Results: After being released from amoebae, Leg. pneumophila were chlorinated at 2 and 5 mg l
Conclusions: Legionella pneumophila replicated from H. vermiformis possess greater chlorine resistance than the cells from A. castellanii .
Significance and Impact of the Study: This study shows the heterogeneity of amoebae-grown Leg. pneumophila in chlorine susceptibility, which should be considered in the control of legionellae proliferation, particularly in the systems where H. vermiformis is dominant, e.g. hot water plumbing. 相似文献
5.
Aim: Bioaugumentation of low temperature biogas production was attempted by addition of cold-adapted Clostridium and a methanogen.
Methods and Results: A psychrotrophic xylanolytic acetogenic strain Clostridium sp. PXYL1 growing optimally at 20°C and pH 5·3 and a Methanosarcina strain, PMET1, growing optimally on acetate and producing methane at 15°C were isolated from a cattle manure digester. Anaerobic conversion of xylose at 15°C with the coculture of the two strains was performed, and batch culture methane production characteristics indicated that methanogenesis occurred via acetate through 'acetoclastic' pathway. Stimulation studies were also undertaken to evaluate the effect of exogenous addition of the coculture on biogas yields at 15°C. Addition of 3 ml of PXYL1 at the rate of 12 × 102 CFU ml−1 increased the biogas 1·7-fold (33 l per kg cowdung) when compared to control (19·3 l per kg cowdung) as well as increased the volatile fatty acid (VFA) levels to 3210 mg l−1 when compared to 1140 mg l−1 in controls. Exogenous of addition of 10 ml PMET1 inoculum at the rate of 6·8 ± 102 CFU ml−1 in addition to PXYL1 served to further improve the biogas yields to 46 l kg−1 as well as significantly brought down the VFA levels to 1350 mg l−1 .
Conclusions: Our results suggest that the rate-limiting methanogenic step at low temperatures could be overcome and that biogas yields improved by manipulating the population of the acetoclastic methanogens.
Significance and Impact of the Study: Stimulation of biomethanation at low temperature by coculture. 相似文献
Methods and Results: A psychrotrophic xylanolytic acetogenic strain Clostridium sp. PXYL1 growing optimally at 20°C and pH 5·3 and a Methanosarcina strain, PMET1, growing optimally on acetate and producing methane at 15°C were isolated from a cattle manure digester. Anaerobic conversion of xylose at 15°C with the coculture of the two strains was performed, and batch culture methane production characteristics indicated that methanogenesis occurred via acetate through 'acetoclastic' pathway. Stimulation studies were also undertaken to evaluate the effect of exogenous addition of the coculture on biogas yields at 15°C. Addition of 3 ml of PXYL1 at the rate of 12 × 10
Conclusions: Our results suggest that the rate-limiting methanogenic step at low temperatures could be overcome and that biogas yields improved by manipulating the population of the acetoclastic methanogens.
Significance and Impact of the Study: Stimulation of biomethanation at low temperature by coculture. 相似文献
6.
Assunção P de la Fe C Antunes NT Rosales RS Ruiz de Galarreta CM Poveda JB 《Journal of applied microbiology》2006,100(4):878-884
Aims: The potential of using flow cytometry (FC) in combination with a fluorescent dye (SYBR green-I) for rapidly estimating Mycoplasma mycoides subSPS. mycoides large-colony type (MmmLC) in broth culture was examined.
Methods and Results: The FC analysis was performed by staining the MmmLC cells with a fluorescent dye, SYBR green-I (SYBR), and the results were compared with plate count method (colony forming units, – CFUs). There was a good correlation (linear regression, r2 = 0·93) between mycoplasma counts determined by FC (cells ml−1 ) and by traditional plate count method (CFU ml−1 ). The lowest bacterial concentration detected by FC and traditional plate count was of the order of 104 cells ml−1 and 103 CFU ml−1 , respectively. FC method allowed results in 20–30 min, whereas at least 24 h were necessary to obtain results with the traditional plate count method (CFU).
Conclusion: Growth rates of MmmLC in broth medium determined by FC were highly reproducible and correlated well with mycoplasma counts assessed by the plate count method.
Significance and Impact of the Study: These findings suggest that FC could be a good alternative to replace other time-consuming techniques that are currently used to enumerate mycoplasma in broth medium, such as plate count method (CFU). 相似文献
Methods and Results: The FC analysis was performed by staining the MmmLC cells with a fluorescent dye, SYBR green-I (SYBR), and the results were compared with plate count method (colony forming units, – CFUs). There was a good correlation (linear regression, r
Conclusion: Growth rates of MmmLC in broth medium determined by FC were highly reproducible and correlated well with mycoplasma counts assessed by the plate count method.
Significance and Impact of the Study: These findings suggest that FC could be a good alternative to replace other time-consuming techniques that are currently used to enumerate mycoplasma in broth medium, such as plate count method (CFU). 相似文献
7.
Aims: To evaluate the effectiveness of organic acids and supercritical carbon dioxide (SC-CO2 ) treatments as well as their combined effect for the reduction of nonpathogenic Escherichia coli and three pathogenic bacteria in fresh pork.
Methods and Results: The different treatment conditions were as follows: (i) treatment with acetic (1%, 2% or 3%) or lactic acid (1%, 2% or 3%) only, (ii) treatment with SC-CO2 at 12 MPa and 35°C for 30 min only and (iii) treatment with 3% acetic or lactic acid followed by treatment with SC-CO2 . Within the same organic acid concentration, the lactic and acetic acid treatments had similar reductions. For the combined treatment of lactic acid and SC-CO2 , micro-organism levels were maximally reduced, ranging from 2·10 to 2·60 log CFU cm−2 ( E. coli , 2·58 log CFU cm−2 ; Listeria monocytogenes , 2·60 log CFU cm−2 ; Salmonella typhimurium , 2·33 log CFU cm−2 ; E. coli O157:H7, 2·10 log CFU cm−2 ).
Conclusions: The results of this study indicate that the combined treatments of SC-CO2 and organic acids were more effective at destroying foodborne pathogens than the treatments of SC-CO2 or organic acids alone.
Significance and Impact of the Study: The combination treatment of SC-CO2 and organic acids may be useful in the meat industry to help increase microbial safety. 相似文献
Methods and Results: The different treatment conditions were as follows: (i) treatment with acetic (1%, 2% or 3%) or lactic acid (1%, 2% or 3%) only, (ii) treatment with SC-CO
Conclusions: The results of this study indicate that the combined treatments of SC-CO
Significance and Impact of the Study: The combination treatment of SC-CO
8.
S.J. Altman L.K. McGrath C.A. Souza J.K. Murton A.K. Camper 《Journal of applied microbiology》2009,107(1):287-299
Aims: The hypothesis that surrogate planktonic pathogens ( Bacillus cereus and polystyrene microspheres) could be integrated in biofilms and protected from decontamination was tested.
Methods and Results: Pseudomonas fluorescens biofilms were grown on polyvinyl chloride coupons in annular reactors under low nutrient conditions. After biofilm growth, B. cereus spores and polystyrene microspheres (an abiotic control) were introduced separately. Shear stress at the biofilm surface was varied between 0·15 and 1·5 N m−2 . The amount of surrogate pathogens introduced ranged from approximately 105 CFU ml−1 to 1010 spheres ml−1 . The quantity of surrogate pathogens integrated in the biofilm was proportional to the amount introduced. In 14 of the 16 cases, 0·4–3·0% of the spores or spheres introduced were measured in the biofilms. The other two cases had 10% and 21% of the spores detected. Data suggested that the spores germinated in the system. The amount of surrogate pathogens detected in the biofilms was higher in the mid-shear range. Chlorine treatment reduced the quantity of both surrogate pathogens and biofilm organisms. In one experiment, the biofilms and B. cereus recovered when the chlorine treatment was terminated.
Conclusions: Planktonic surrogate pathogens can be integrated in biofilms and protected from chlorination decontamination.
Significance and Impact of the Study: This knowledge assists in understanding the impact of biofilms on harbouring potential pathogens in drinking-water systems and protecting the pathogens from decontamination. 相似文献
Methods and Results: Pseudomonas fluorescens biofilms were grown on polyvinyl chloride coupons in annular reactors under low nutrient conditions. After biofilm growth, B. cereus spores and polystyrene microspheres (an abiotic control) were introduced separately. Shear stress at the biofilm surface was varied between 0·15 and 1·5 N m
Conclusions: Planktonic surrogate pathogens can be integrated in biofilms and protected from chlorination decontamination.
Significance and Impact of the Study: This knowledge assists in understanding the impact of biofilms on harbouring potential pathogens in drinking-water systems and protecting the pathogens from decontamination. 相似文献
9.
Aims: This study was aimed to investigate the effects of a high-pressure homogenization (HPH) treatment on some micro-organisms, involved in the spoilage of fruit juices.
Methods and Results: Lactobacillus plantarum , Lactobacillus brevis , Bacillus coagulans cells, Saccharomyces bayanus , Pichia membranaefaciens and Rhodotorula bacarum were separately inoculated in a saline solution (0·9% NaCl); the initial inoculum was ca. 5 log CFU ml−1 . Then, the samples were processed through a homogenizer at 10–150 MPa for 1, 2 or 3 times. Yeasts were completely inactivated at 50–110 MPa with a single pass treatment, while lactic acid bacteria counts were reduced to approximately 1 log CFU ml−1 after a three-steps HPH processing.
Conclusions: Yeasts were the most sensitive micro-organisms, followed by B. coagulans . On the other hand, lactic acid bacteria appeared resistant to HPH.
Significance and Impact of the Study: The results of this study provided some useful information on the susceptibility of microflora of juices to homogenization; moreover, they suggested that HPH could be used successfully to inactivate yeasts. 相似文献
Methods and Results: Lactobacillus plantarum , Lactobacillus brevis , Bacillus coagulans cells, Saccharomyces bayanus , Pichia membranaefaciens and Rhodotorula bacarum were separately inoculated in a saline solution (0·9% NaCl); the initial inoculum was ca. 5 log CFU ml
Conclusions: Yeasts were the most sensitive micro-organisms, followed by B. coagulans . On the other hand, lactic acid bacteria appeared resistant to HPH.
Significance and Impact of the Study: The results of this study provided some useful information on the susceptibility of microflora of juices to homogenization; moreover, they suggested that HPH could be used successfully to inactivate yeasts. 相似文献
10.
Aim: To explore safe guidelines for manufacturers and consumers to prepare, handle and store dry infant formula (DIF) to protect infants against Cronobacter spp.
Methods and Results: Selected strains (2.45, FSM 293, ATCC-12868, FSM-271) screened from 68 strains of Cronobacter spp . were used to study growth and survival in commercial DIF. Prototype growth patterns in Enterobacteriaceae enrichment broth (EEB) containing a cocktail comprised of ATCC 12868, ATCC 29004, ATCC 29544 and ATCC 51329 showed a rapid increase in cell count (2·0 log10 to 6·2 log10 CFU ml−1 ). Infant formula provided a better protective environment for the cells of Cronobacter strains than did buffered peptone water . Experiments on survival in inoculated (104 –106 CFU ml−1 ) reconstituted infant formula (RIF), preparation temperature, the effect of preparation volume (one-serving or two-serving) and effect of storage at room temperature for up to 10 h provided information to develop consumer guidelines for DIF preparation and handling.
Conclusions: Reconstituted DIF in water at >70°C in larger volumes, minimizing storage time before feeding and storing unused reconstituted formulate at <4°C, may reduce the risk of Cronobacter infection in infants.
Significance and Impact of the Study: Meningitis, necrotizing enterocolitis and bacteremia in premature babies has been linked to contaminated milk powder and DIF; better handling practices may improve the safety of these foods for neonates. 相似文献
Methods and Results: Selected strains (2.45, FSM 293, ATCC-12868, FSM-271) screened from 68 strains of Cronobacter spp . were used to study growth and survival in commercial DIF. Prototype growth patterns in Enterobacteriaceae enrichment broth (EEB) containing a cocktail comprised of ATCC 12868, ATCC 29004, ATCC 29544 and ATCC 51329 showed a rapid increase in cell count (2·0 log
Conclusions: Reconstituted DIF in water at >70°C in larger volumes, minimizing storage time before feeding and storing unused reconstituted formulate at <4°C, may reduce the risk of Cronobacter infection in infants.
Significance and Impact of the Study: Meningitis, necrotizing enterocolitis and bacteremia in premature babies has been linked to contaminated milk powder and DIF; better handling practices may improve the safety of these foods for neonates. 相似文献
11.
A. Hidaka T. Hokyo K. Arikawa S. Fujihara J. Ogasawara A. Hase Y. Hara-Kudo Y. Nishikawa 《Journal of applied microbiology》2009,106(2):410-420
Aims: The source and routes of diarrhoeagenic Escherichia coli (DEC) have not been clarified because it is difficult to detect these organisms in samples with numerous coliform bacteria. We have developed multiplex real-time PCR assays for exhaustive detection of DEC.
Methods and Results: Primers and TaqMan probes were designed to amplify and quantify one gene ( eae , stx1 , stx2 , elt , est , virB , aggR , astA, and afaB ) from each of seven pathotypes of DEC, in duplex or triplex reactions under the same PCR cycling conditions. Specificity was confirmed using 860 strains including 88 DEC strains. The fluorescence threshold cycle and DNA concentrations correlated with decision coefficients of more than 0·99. Subsequently, meat samples and enrichment broths were spiked with DEC and the assays used to detect the genes. The detection limits varied from 7·1 × 102 to 1·1 × 104 CFU ml−1 , depending on the target genes. All meat samples spiked with a variety of DEC (more than 10 CFU 10 g−1 ) were found to be positive by the method.
Conclusions: The present system allows for the efficient and simultaneous determination of various DEC pathotypes.
Significance and Impact of the Study: This system makes epidemiological investigations for DEC sensitive and quick, and is a useful tool to clarify the source and routes of DEC. 相似文献
Methods and Results: Primers and TaqMan probes were designed to amplify and quantify one gene ( eae , stx1 , stx2 , elt , est , virB , aggR , astA, and afaB ) from each of seven pathotypes of DEC, in duplex or triplex reactions under the same PCR cycling conditions. Specificity was confirmed using 860 strains including 88 DEC strains. The fluorescence threshold cycle and DNA concentrations correlated with decision coefficients of more than 0·99. Subsequently, meat samples and enrichment broths were spiked with DEC and the assays used to detect the genes. The detection limits varied from 7·1 × 10
Conclusions: The present system allows for the efficient and simultaneous determination of various DEC pathotypes.
Significance and Impact of the Study: This system makes epidemiological investigations for DEC sensitive and quick, and is a useful tool to clarify the source and routes of DEC. 相似文献
12.
Aims: To determine the effectiveness of sucrose monolaurate (SML) and sucrose monocaprate (SMC), alone and in combination with ethylenediaminetetraacetic acid (EDTA), propionic acid (PA) or citric acid (CA) in reducing mesophilic aerobic bacteria (MAB) and Yersinia enterocolitica O:9 populations on eggshells and their damage potential on the microstructure of shell cuticle.
Methods and Results: Uninoculated eggs and eggs submerged in a solution of Y. enterocolitica were immersed in solutions of the various treatments. MAB and Y. enterocolitica counts on the surface of the eggs were carried out before and after treatment. MAB counts decreased less than 2 logs on uninoculated eggshells irrespective of treatment and reductions of 3·2 and 3·0 logs of Y. enterocolitica were obtained with 1000 μg ml−1 SML plus 0·1% CA or 1000 μg ml−1 SML plus 600 μg ml−1 EDTA solutions, respectively. Y. enterocolitica 2/O:9 was recovered from natural microflora. Use of blue lake staining revealed minimal damage to the shells from the washing treatments.
Conclusions: SML and SMC at 1000 μg ml−1 combined with CA or EDTA could be effective in reducing Y. enterocolitica on eggshells with a minimal risk of later bacterial recontamination.
Significance and Impact of the Study: Eggs are a recognized vehicle for transmission of Y enterocolitica although a prevalence of only 2·7% was detected in this study. Washing eggs in solutions containing SML or SMC could eliminate Y. enterocolitica contamination of egg shells. 相似文献
Methods and Results: Uninoculated eggs and eggs submerged in a solution of Y. enterocolitica were immersed in solutions of the various treatments. MAB and Y. enterocolitica counts on the surface of the eggs were carried out before and after treatment. MAB counts decreased less than 2 logs on uninoculated eggshells irrespective of treatment and reductions of 3·2 and 3·0 logs of Y. enterocolitica were obtained with 1000 μg ml
Conclusions: SML and SMC at 1000 μg ml
Significance and Impact of the Study: Eggs are a recognized vehicle for transmission of Y enterocolitica although a prevalence of only 2·7% was detected in this study. Washing eggs in solutions containing SML or SMC could eliminate Y. enterocolitica contamination of egg shells. 相似文献
13.
Aims: To develop a new rapid real-time polymerase chain reaction (PCR) based detection system for Vibrio parahaemolyticus ( V. parahaemolyticus ) applicable to raw oyster samples.
Methods and Results: V. parahaemolyticus cells were artificially inoculated to oysters. Samples were homogenized in 100 ml of sterile saline water and serially diluted to 1·5 CFU ml−1 level. One millilitre of diluents was centrifuged and the pellet was resuspended with 100 μ l of de-ionized water. DNA was extracted by boiling for 20 min, and 0·5 μ l was used as a template for PCR reaction. Real-time PCR was performed with TMC-1000 system (1 μ l PCR system). The detection system was found to achieve detection limit of 1·5 CFU g−1 for V. parahaemolyticus . Furthermore, the specificities of these assay systems were confirmed with more than 20 bacterial strains, including various Vibrio species.
Conclusions: Rapid and sensitive food-borne pathogen detection techniques for V. parahaemolyticus is important to the food industry and consumers. The direct detection of V. parahaemolyticus from food is possible with micro real-time PCR system.
Significance and Impact of the Study: This study shows that oyster samples can be tested for V. parahaemolyticus with a rapid, specific and simple procedure. 相似文献
Methods and Results: V. parahaemolyticus cells were artificially inoculated to oysters. Samples were homogenized in 100 ml of sterile saline water and serially diluted to 1·5 CFU ml
Conclusions: Rapid and sensitive food-borne pathogen detection techniques for V. parahaemolyticus is important to the food industry and consumers. The direct detection of V. parahaemolyticus from food is possible with micro real-time PCR system.
Significance and Impact of the Study: This study shows that oyster samples can be tested for V. parahaemolyticus with a rapid, specific and simple procedure. 相似文献
14.
C. Srisuk P. Chaivisuthangkura S. Rukpratanporn S. Longyant P. Sridulyakul P. Sithigorngul 《Letters in applied microbiology》2010,50(1):36-42
Aims: The present study was aimed to develop a loop-mediated isothermal amplification (LAMP) assay for rapid and specific detection of Vibrio cholerae .
Methods and Results: A set of five designed primers that recognized specifically the V. cholerae ompW gene was used. The optimized time and temperature conditions for the LAMP assay were 75 min at 65°C, respectively. The LAMP method accurately identified 16 isolates of V. cholerae but did not detect 28 non- cholerae Vibrio isolates and 37 non- Vibrio bacterial isolates. The sensitivity of LAMP for V. cholerae detection in pure cultures was 2·2 × 103 CFU ml−1 or equivalent to 8 CFU per reaction. In the case of spiked shrimp samples without enrichment, the detection limit for V. cholerae was 2·2 × 104 CFU g−1 or equivalent to 20 CFU per reaction, while that of PCR was 100 CFU per reaction.
Conclusion: The developed LAMP assay targeting ompW gene was rapid, specific and sensitive for V. cholerae detection.
Significant and Impact of the study: The developed LAMP assay appears to be precise, accurate and a valuable tool for detection of V. cholerae . This assay can replace laborious biochemical tests for the identification of V. cholerae in contaminated food sample. 相似文献
Methods and Results: A set of five designed primers that recognized specifically the V. cholerae ompW gene was used. The optimized time and temperature conditions for the LAMP assay were 75 min at 65°C, respectively. The LAMP method accurately identified 16 isolates of V. cholerae but did not detect 28 non- cholerae Vibrio isolates and 37 non- Vibrio bacterial isolates. The sensitivity of LAMP for V. cholerae detection in pure cultures was 2·2 × 10
Conclusion: The developed LAMP assay targeting ompW gene was rapid, specific and sensitive for V. cholerae detection.
Significant and Impact of the study: The developed LAMP assay appears to be precise, accurate and a valuable tool for detection of V. cholerae . This assay can replace laborious biochemical tests for the identification of V. cholerae in contaminated food sample. 相似文献
15.
Aims: The interactions between nonsteroidal anti-inflammatory drugs (NSAID) and Listeria monocytogenes have not been sufficiently documented to date. The aim of this study was to investigate the possible effects of Diclofenac (Dc) in a murine listerial infection model.
Methods and Results: Dc was administered orally at 2·5 μg g−1 to female albino strain of laboratory mouse (BALB/c) thrice postinfection (1 × 108 CFU ml−1 oral challenge with L. monocytogenes ATCC 51774), which resulted in significantly ( P < 0·01) reduced bacterial counts in liver and spleen, decreased (10-fold, P < 0·05) hepatic colonization and necrosis, and caused up-regulation of the expression of inflammatory cytokines (interferon-γ, interleukin-1β, tumour necrosis factor-α), compared with drug-free control.
Conclusions: Dc may be useful as a promising adjuvant to the existing therapies in controlling systemic listerial infection. Further, quantitative structure–activity relationship studies might contribute in manipulating it as a lead compound for the synthesis of new, more effective nonantibiotics, perhaps, devoid of side-effects that could be recommended as a compassionate therapy for listeriosis.
Significance and Impact of the study: This is the first in vivo study designed to evaluate the antilisterial effect of the NSAID Dc with special emphasis on the immunological mechanism of action of the drug. 相似文献
Methods and Results: Dc was administered orally at 2·5 μg g
Conclusions: Dc may be useful as a promising adjuvant to the existing therapies in controlling systemic listerial infection. Further, quantitative structure–activity relationship studies might contribute in manipulating it as a lead compound for the synthesis of new, more effective nonantibiotics, perhaps, devoid of side-effects that could be recommended as a compassionate therapy for listeriosis.
Significance and Impact of the study: This is the first in vivo study designed to evaluate the antilisterial effect of the NSAID Dc with special emphasis on the immunological mechanism of action of the drug. 相似文献
16.
Aims: To evaluate the activities of six Lactobacillus delbrueckii subsp. bulgaricus (LB) strains against 30 Helicobacter pylori strains by agar-well diffusion method.
Methods and Results: LB cultures [4 × 108 –4 × 109 CFU ml−1 ) either were prepared in milk at their native pH, 3·8–5·0, or were adjusted to pH 6·4–7·7. At low and neutralized pH, LB strains inhibited the growth by 40–86·7% and 16·7–66·7% of H. pylori strains, respectively. LB activity was strain-dependent. At low and neutralized pH, one and five H. pylori strains, respectively, were not inhibited by any LB strain. LB2 and LB3, taken together, were active against most metronidazole and clarithromycin resistant strains.
Conclusions: All LB strains inhibited a number of H. pylori strains, including also antibiotic resistant strains. LB activity was strain-dependent and better at low pH. At low pH values, the most active LB strains were LB1, LB2 and LB3, inhibiting 86·7% of H. pylori strains, while at neutralized pH values, the most active LB strains were LB2 and LB3, inhibiting 53·3 and 66·7% of H. pylori strains, respectively.
Significance and Impact of the Study: LB could be utilized in the treatment or prophylaxis of H. pylori infection and warrants clinical investigations. 相似文献
Methods and Results: LB cultures [4 × 10
Conclusions: All LB strains inhibited a number of H. pylori strains, including also antibiotic resistant strains. LB activity was strain-dependent and better at low pH. At low pH values, the most active LB strains were LB1, LB2 and LB3, inhibiting 86·7% of H. pylori strains, while at neutralized pH values, the most active LB strains were LB2 and LB3, inhibiting 53·3 and 66·7% of H. pylori strains, respectively.
Significance and Impact of the Study: LB could be utilized in the treatment or prophylaxis of H. pylori infection and warrants clinical investigations. 相似文献
17.
Kasselaki AM Malathrakis NE Goumas DE Cooper JM Leifert C 《Journal of applied microbiology》2008,105(1):36-41
Aims: To quantify the phytotoxicity and effect of alternative seed treatments based on acidified nitrite and elicitors of plant resistance (Tillekur and Chitosan) against seed-borne inocula of Didymella lycopersici .
Methods and Results: Treatments tested were: nitrite [sodium nitrite in citric acid buffer (pH 2)] at 30, 100 and 300 mmol l−1 and three exposure times (10, 20 and 30 min); Tillekur (in water) at 12·5, 25, 50, 100 and 200 mg ml−1 ; Chitosan (in 0·05% acetic acid) at 2·5, 5, 10 and 50 mg ml−1 . Efficacy of treatments was determined in growth chamber experiments. Nitrite at 300 mmol l−1 was completely effective, as was the fungicide, at controlling disease when applied for less than 20 min. Tillekur was as effective as the fungicide postemergence, but proved to be phytotoxic pre-emergence. Chitosan was significantly less effective than the other treatments.
Conclusions: The high efficacy and low cost of acidified nitrite indicates that it is a suitable alternative to fungicides.
Significance and Impact of the Study: There is currently a lack of effective seed treatments that can be used in organic and low-input crops. Treatments identified in this study can be considered as an effective alternative to chemical control against seed-borne fungal pathogens. 相似文献
Methods and Results: Treatments tested were: nitrite [sodium nitrite in citric acid buffer (pH 2)] at 30, 100 and 300 mmol l
Conclusions: The high efficacy and low cost of acidified nitrite indicates that it is a suitable alternative to fungicides.
Significance and Impact of the Study: There is currently a lack of effective seed treatments that can be used in organic and low-input crops. Treatments identified in this study can be considered as an effective alternative to chemical control against seed-borne fungal pathogens. 相似文献
18.
Aims: To study the efficacy of the lytic phage φS1 in eliminating Pseudomonas fluorescens in the early stage of biofilm formation, using an in situ and real time methodology for cell quantification.
Methods and Results: Cell adhesion and phage infection studies were carried out in a parallel plate flow chamber under laminar conditions. Cells were allowed to adhere until reaching 1·7–1·8 × 106 cells cm−2 and phage infection was performed with two different phage concentrations (2 × 109 PFU ml−1 and 1 × 1010 PFU ml−1 ). Phage concentration clearly affects the speed of infection. The less concentrated phage solution promoted a three times slower rate of cell removal but did not affect the overall percentage of cell removal. In fact, after a longer infection period the less concentrated phage solution reached the same 93% cell removal value.
Conclusions: Phages are efficient in the eradication of bacterial cells at the early stage of biofilm formation and their presence at the surface did not allow bacterial recolonization of the surface.
Significance and Impact of the Study: To date, no published studies have been made concerning in situ and real time quantification of cell removal from surfaces due to phage action. 相似文献
Methods and Results: Cell adhesion and phage infection studies were carried out in a parallel plate flow chamber under laminar conditions. Cells were allowed to adhere until reaching 1·7–1·8 × 10
Conclusions: Phages are efficient in the eradication of bacterial cells at the early stage of biofilm formation and their presence at the surface did not allow bacterial recolonization of the surface.
Significance and Impact of the Study: To date, no published studies have been made concerning in situ and real time quantification of cell removal from surfaces due to phage action. 相似文献
19.
Aims: To test the effect of bovicin HC5 against vegetative cells and endospores of Alicyclobacillus acidoterrestris DSMZ 2498 in synthetic media and in acidic mango pulp.
Methods and Results: Alicyclobacillus acidoterrestris was grown in synthetic medium at 40°C and pH 4·0. The effect on vegetative cells was assayed by adding bovicin HC5 to synthetic medium (40–160 AU ml−1 ) or to mango pulp (100 AU ml−1 ) at various pH values and determining the effect on growth (OD600nm ) and viable cell number, respectively. The effect of bovicin HC5 on spore germination and thermal sensitivity of A. acidoterrestris was tested in mango pulp (pH 4·0) containing 80 AU ml−1 of bovicin HC5. Bovicin HC5 was bactericidal against vegetative cells of A. acidoterrestris at different pH values and showed sporicidal activity against endospores of this bacterium. When spores of A. acidoterrestris were heat treated in the presence of bovicin HC5, D -values decreased 77% to 95% compared to untreated controls at temperatures ranging from 80 to 95°C.
Conclusion: Bovicin HC5 was bactericidal and sporicidal against A. acidoterrestrsi DSMZ 2498.
Significance and Impact of the Study: These results indicated that bovicin HC5 has potential to prevent spoilage of acidic fruit juices by thermocidophilic spore-forming bacteria. 相似文献
Methods and Results: Alicyclobacillus acidoterrestris was grown in synthetic medium at 40°C and pH 4·0. The effect on vegetative cells was assayed by adding bovicin HC5 to synthetic medium (40–160 AU ml
Conclusion: Bovicin HC5 was bactericidal and sporicidal against A. acidoterrestrsi DSMZ 2498.
Significance and Impact of the Study: These results indicated that bovicin HC5 has potential to prevent spoilage of acidic fruit juices by thermocidophilic spore-forming bacteria. 相似文献
20.
Aims: To develop a real-time polymerase chain reaction (PCR) hybridization probe assay for rapid and specific detection of thermostable direct haemolysin-producing Vibrio parahaemolyticus.
Methods and Results: Primers and hybridization probes were designed to target the toxR and tdh2 genes. Mismatches were introduced in the tdh2 primers for specific amplification of the target. The 3' ends of donor probes for both genes were labelled with fluorescein. The 5' ends of recipient probes for tdh2 and toxR were labelled with LC Red 640 and LC Red 705, respectively. The real-time assay was evaluated against conventional biochemical tests and the KAP-RPLA kit (Kanagawa phenomenon detection kit by reverse passive latex agglutination). toxR and tdh2 were detected in 100% and 91% of clinical V. parahaemolyticus isolates ( n = 118), respectively. Specificity and sensitivity of the real-time assay for toxR and tdh2 were 100%, respectively. Dynamic range of detection for toxR was 107 –101 CFU ml−1 and that for tdh2 was 107 –104 CFU ml−1 .
Conclusions: The LightCycler assay described is sensitive and highly specific for detection of pathogenic V. parahaemolyticus in a single reaction tube within 80 min.
Significance and Impact of the Study: The assay developed allows accurate detection of pathogenic V. parahaemolyticus , which is valuable for rapid tracing of infection source during outbreaks. 相似文献
Methods and Results: Primers and hybridization probes were designed to target the toxR and tdh2 genes. Mismatches were introduced in the tdh2 primers for specific amplification of the target. The 3' ends of donor probes for both genes were labelled with fluorescein. The 5' ends of recipient probes for tdh2 and toxR were labelled with LC Red 640 and LC Red 705, respectively. The real-time assay was evaluated against conventional biochemical tests and the KAP-RPLA kit (Kanagawa phenomenon detection kit by reverse passive latex agglutination). toxR and tdh2 were detected in 100% and 91% of clinical V. parahaemolyticus isolates ( n = 118), respectively. Specificity and sensitivity of the real-time assay for toxR and tdh2 were 100%, respectively. Dynamic range of detection for toxR was 10
Conclusions: The LightCycler assay described is sensitive and highly specific for detection of pathogenic V. parahaemolyticus in a single reaction tube within 80 min.
Significance and Impact of the Study: The assay developed allows accurate detection of pathogenic V. parahaemolyticus , which is valuable for rapid tracing of infection source during outbreaks. 相似文献