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1.
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
2.
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
3.
Quantification of pathogenic micro-organisms in the sludge from treated hospital wastewater 总被引:1,自引:1,他引:0
The sludge from hospital waste treatment facilities is a potential source of infectious organisms. The average numbers of micro-organisms in the sludge of hospital wastewater in Taiwan were as follows: total count 8·1 × 107 cfu g−1 (dry weight of sludge), and 1·4 × 106 , 3·6 × 105 , 1·6 × 105 , 2·2 × 105 and 5·5 × 104 cfu g−1 (dry weight of sludge) for total coliforms, faecal coliforms, faecal streptococci, Pseudomonas aeruginosa and Salmonella spp., respectively . Salmonella spp. were detected in 37% (10 of 27) of the sludges from hospital wastewaters. Therefore, the treatment of such sludge to reduce pathogenic micro-organisms should be considered. 相似文献
4.
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
5.
O.G. Nagel M.P. Molina J.C. Basílico M.L.Zapata R.L. Althaus 《Letters in applied microbiology》2009,48(6):744-749
Aims: To use experimental design techniques and a multiple logistic regression model to optimize a microbiological inhibition test with dichotomous response for the detection of Penicillin G in milk.
Methods and Results: A 23 × 22 robust experimental design with two replications was used. The effects of three control factors (V: culture medium volume, S: spore concentration of Geobacillus stearothermophilus , I: indicator concentration), two noise factors (Dt: diffusion time, Ip: incubation period) and their interactions were studied. The V, S, Dt, Ip factors and V × S, V × Ip, S × Ip interactions showed significant effects.
Conclusions: The use of 100 μ l culture medium volume, 2 × 105 spores ml−1 , 60 min diffusion time and 3 h incubation period is recommended. In these elaboration conditions, the penicillin detection limit was of 3·9 μ g l−1 , similar to the maximum residue limit (MRL). Of the two noise factors studied, the incubation period can be controlled by means of the culture medium volume and spore concentration.
Significance and Impact of the Study: We were able to optimize bioassays of dichotomous response using an experimental design and logistic regression model for the detection of residues at the level of MRL, aiding in the avoidance of health problems in the consumer. 相似文献
Methods and Results: A 2
Conclusions: The use of 100 μ l culture medium volume, 2 × 10
Significance and Impact of the Study: We were able to optimize bioassays of dichotomous response using an experimental design and logistic regression model for the detection of residues at the level of MRL, aiding in the avoidance of health problems in the consumer. 相似文献
6.
Seasonal patterns of viruses, bacteria and dissolved organic carbon in a riverine wetland 总被引:3,自引:0,他引:3
SUMMARY 1. Viral and bacterial abundances were studied in relation to environmental attributes over an annual period, for both planktonic and attached (sediment, aquatic macrophyte and submerged wood) habitats, in a riverine wetland.
2. Annual mean abundance of planktonic viruses ranged from 2.3 × 105 −3.8 × 105 particles mL−1 and varied according to sampling site. Significant seasonal patterns in viral abundance were evident and appeared to be linked to variations in bacterial abundance, dissolved organic carbon and inorganic nutrients.
3. Annual mean abundance of viruses associated with surfaces ranged from 1.3 × 106 particles cm−2 on aquatic macrophytes to 1.1 × 107 particles cm−2 on wood and also showed seasonal patterns. The difference in viral dynamics among the different sites emphasizes the importance of considering habitat diversity within wetlands when examining microbial communities. 相似文献
2. Annual mean abundance of planktonic viruses ranged from 2.3 × 10
3. Annual mean abundance of viruses associated with surfaces ranged from 1.3 × 10
7.
SUMMARY 1. Temporary ponds are inhabited by a variety of invertebrates, of which anostracans are an important group. We studied the lifetables of male and female anostracan Streptocephalus mackini at 3 algal concentrations (0.5 × 106 , 1.0 × 106 and 1.5 × 106 cells mL−1 ).
2. Regardless of sex, S. mackini showed better survivorship at lower food levels. The longest average lifespan observed was 85 ± 2 days for males fed Chlorella at 0.5 × 106 cells mL−1 .
3. Both net reproductive rate and generation time decreased with increasing food level. The highest net reproductive rate was about 120 cysts per female. The longest generation time of about 40 days, observed at 0.5 × 106 cells mL−1 , was more than three times that at 1.5 × 106 cells mL−1 .
4. The rate of population increase ( r ) was nearly the same (0.31 ± 0.06) at high (1.5 × 106 cells mL−1 ) and intermediate (1.0 × 106 cells mL−1 ) food levels. The r -value at low food level (0.5 × 106 cells mL−1 of Chlorella ) was 0.20 ± 0.01 per day. 相似文献
2. Regardless of sex, S. mackini showed better survivorship at lower food levels. The longest average lifespan observed was 85 ± 2 days for males fed Chlorella at 0.5 × 10
3. Both net reproductive rate and generation time decreased with increasing food level. The highest net reproductive rate was about 120 cysts per female. The longest generation time of about 40 days, observed at 0.5 × 10
4. The rate of population increase ( r ) was nearly the same (0.31 ± 0.06) at high (1.5 × 10
8.
Aims: The ability to transform Vibrio spp. is limited by the extracellular nuclease that their cells secrete. The reported transformation efficiency of this organism is 102 –105 transformants per microgram DNA. We tried different buffers and conditions, aiming to elevate its transformation efficiency.
Methods and Results: MgCl2 and sucrose are often included in the washing and/or electroporation buffers to stabilize the cell membrane. However, Mg2+ is required for production and activity of the extracellular nuclease. A simple electroporation buffer lacking Mg2+ was found to increase transformation efficiency dramatically, to levels 50-fold more than the buffers containing Mg2+ . To maintain the stability of the cell membranes, Mg2+ was replaced with high concentrations of sucrose, from 272 to 408 mmol l−1 . With the new buffers, the transformation efficiency of Vibrio parahaemolyticus was increased to 2·2 × 106 transformants per microgram DNA.
Conclusions: Mg2+ in the buffer adversely affected transformation of V. parahaemolyticus by electroporation. The cell membranes of vibrio can be stabilized by high concentration of sucrose when Mg2+ is absent.
Significance and Impact of the Study: A greater transformation efficiency can facilitate the genetic analysis of an organism and its pathogenicity. Buffers lacking Mg2+ can be used for other nuclease-producing organisms. 相似文献
Methods and Results: MgCl
Conclusions: Mg
Significance and Impact of the Study: A greater transformation efficiency can facilitate the genetic analysis of an organism and its pathogenicity. Buffers lacking Mg
9.
M.C. Roberts O.O. Soge M.A. Giardino E. Mazengia G. Ma J.S. Meschke 《Journal of applied microbiology》2009,107(1):300-307
Aims: The aim of the study was to determine if vancomycin-resistant Enterococcus spp. [VRE] carrying vanA and/or vanB genes were present in public marine beaches and a fishing pier [2001–2003, 2008] from Washington and California [2008].
Methods: PCR assays for the vanA and/or vanB genes with verification by DNA–DNA hybridization of the PCR products were used. Positive isolates were speciated using the BD BBL Crystal™ Identification and/or by sequencing the 16S ribosomal region.
Results: Eighteen (8%) of 227 isolates including Enterococcus faecalis , Enterococcus faecium , Enterococcus casseliflavus/gallinarum and a Staphylococcus epidermidis carrying vanA and/or vanB genes, from four of six Washington and one of two California sites, were identified. Selected VRE and the S. epidermidis were able to transfer their van genes to an E. faecalis recipient at frequencies ranging from 1·9 × 10−6 to 6·7 × 10−9 .
Conclusions: Vancomycin-resistant Enterococcus spp. was isolated from five of the seven sites suggesting that other North America public beaches could be the reservoirs for VRE and should be assessed.
Significance & Impact of the Study: This is the first report of isolation and characterization of VRE strains (and a vanB Staphylococcus sp.) from North American environmental sources suggesting that public beaches may be a reservoir for possible transmission of VRE to beach visitors. 相似文献
Methods: PCR assays for the vanA and/or vanB genes with verification by DNA–DNA hybridization of the PCR products were used. Positive isolates were speciated using the BD BBL Crystal™ Identification and/or by sequencing the 16S ribosomal region.
Results: Eighteen (8%) of 227 isolates including Enterococcus faecalis , Enterococcus faecium , Enterococcus casseliflavus/gallinarum and a Staphylococcus epidermidis carrying vanA and/or vanB genes, from four of six Washington and one of two California sites, were identified. Selected VRE and the S. epidermidis were able to transfer their van genes to an E. faecalis recipient at frequencies ranging from 1·9 × 10
Conclusions: Vancomycin-resistant Enterococcus spp. was isolated from five of the seven sites suggesting that other North America public beaches could be the reservoirs for VRE and should be assessed.
Significance & Impact of the Study: This is the first report of isolation and characterization of VRE strains (and a vanB Staphylococcus sp.) from North American environmental sources suggesting that public beaches may be a reservoir for possible transmission of VRE to beach visitors. 相似文献
10.
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
11.
OBSERVATIONS ON THE MICROFLORA OF MINCED CHICKEN MEAT IRRADIATED WITH 4 MeV CATHODE RAYS 总被引:4,自引:3,他引:1
MARGARET J. THORNLEY 《Journal of applied microbiology》1957,20(2):286-298
SUMMARY: Experiments are described in which minced chicken meat, packed anaerobically, was irradiated at room temperature and in the frozen state with a wide range of doses of 4 MeV cathode rays. Sterility was achieved in 14 out of 15 samples which had received 2 × 106 rads or more. Doses of 0·5 and 1·0 × 106 rads allowed survival of a few bacteria/g, usually spore formers. Bacterial counts indicated an approximately logarithmic decrease in numbers at lower doses, while freezing reduced the bactericidal effect.
The storage life at 5° was prolonged only slightly by doses of 5 × 104 and 10 × 104 rads, and highly variable results were obtained with 17·5 × 104 rads. A dose of 25 × 104 rads, however, increased the storage life very considerably. The types of bacteria present initially, and after irradiation with low doses and storage at 5°, were studied. After storage for 12 days or more various types of nonsporing Gram-positive rods were predominant in almost all samples, both control and irradiated. Streptococci were also important where irradiation with 17·5 × 104 and 25 × 104 rads was followed by long storage. 相似文献
The storage life at 5° was prolonged only slightly by doses of 5 × 10
12.
Impact of biological activity on detritus transported in the lower river Rhine: an exercise in ecosystem analysis 总被引:4,自引:0,他引:4
SUMMARY. 1. Published data are used to construct a tentative carbon budget for the ecosystem of the lower river Rhine and its sedimentation areas in The Netherlands.
2. It is estimated that 287 × 106 kg Cy−1 of particulate organic material is transported by the river Rhine, and 100 × 106 kgCy−1 of this material is deposited in the delta.
3. Phytoplankton and nitrifying bacteria seem to contribute significantly to the carbon budget, by producing c. 78 × 106 kgCy−l .
4. The mineralization in the water (estimated from routine determinations of biological oxygen demand and from in situ diurnal fluctuations of oxygen) and in the bottom (estimated from the denitrification rates in the delta, from the production rate of methane and from overall oxygen consumption) is shown to degrade c. 50% of the carbon input plus autochthonous production.
5. The carbon budget and oxygen regime in the lower Rhine suggest that after decades of severe organic pollution the river has more or less resumed the normal, slightly heterotrophic state of a large lowland river. 相似文献
2. It is estimated that 287 × 10
3. Phytoplankton and nitrifying bacteria seem to contribute significantly to the carbon budget, by producing c. 78 × 10
4. The mineralization in the water (estimated from routine determinations of biological oxygen demand and from in situ diurnal fluctuations of oxygen) and in the bottom (estimated from the denitrification rates in the delta, from the production rate of methane and from overall oxygen consumption) is shown to degrade c. 50% of the carbon input plus autochthonous production.
5. The carbon budget and oxygen regime in the lower Rhine suggest that after decades of severe organic pollution the river has more or less resumed the normal, slightly heterotrophic state of a large lowland river. 相似文献
13.
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
14.
WLIP, a lipodepsipeptide of Pseudomonas 'reactans', as inhibitor of the symptoms of the brown blotch disease of Agaricus bisporus 总被引:1,自引:0,他引:1
C. Soler-Rivas N. Arpin J. M. Olivier H. J. Wichers 《Journal of applied microbiology》1999,86(4):635-641
A cell-free crude extract containing the white line inducing principle (WLIP), a lipodepsipeptide produced by Pseudomonas 'reactans' , could inhibit browning of mushrooms caused by Pseudomonas tolaasii . Mushrooms inoculated with Ps. tolaasii at concentrations of 2·7 × 106 cfu ml−1 or higher showed the symptoms of the disease after 2 d of incubation. Mushroom caps treated with various concentrations of a crude WLIP preparation, and later inoculated with bacterial concentrations higher than the threshold value, did not develop the symptoms of the disease. One milligram of a crude WLIP preparation could block 50% of the symptoms caused by 1·2 × 107 cfu. The inhibition of browning was effective when incubating at low temperatures for 4 d. A suspension containing 1·6 mg ml−1 of pure WLIP was also able to inhibit the symptoms of brown blotch disease induced by 7·6 × 106 cfu ml−1 of Ps. tolaasii . 相似文献
15.
A simple, rapid and sensitive PCR-based method was developed for the detection of all five subspecies of Erwinia carotovora , including subsp. carotovora and subsp. atroseptica , and all pathovars/biovars of Erwinia chrysanthemi , on plant tissue culture material. Primers SR3F and SR1cR, based on a conserved region of the 16S rRNA gene, amplified a DNA fragment of 119 bp from all 65 such strains tested. Detection limits of the method in vitro were 2·0 × 102 –3·4 × 103 cfu ml−1 (equivalent to 1–17 cfu per PCR) and, following extraction of genomic DNA from plant extract, detection limits were 2·3 × 102 –1·9 × 104 cfu per microplant sample (equivalent to 5 cfu – 3·8 × 102 cfu per PCR). To improve the sensitivity of the method in planta , to obviate the need for complex and laborious DNA extractions, and to remove inhibitory substances present in the plant extract, an enrichment step was included prior to PCR. Following enrichment, the sensitivity of detection was <10 cfu per microplant sample. This method provides the first sensitive means of detecting latent infection caused by several economically important soft rot erwinias simultaneously on potato tissue culture material. 相似文献
16.
River flow and fish abundance in a South African estuary 总被引:3,自引:0,他引:3
The ichthyofauna of the Thukela Estuary, a small (55 ha), shallow (<1·5 m) system on the KwaZulu-Natal coast (mean annual river runoff of 3865 × 106 m3 , from a large catchment of 29 000 km2 , is seasonal: peak inputs occurring between November and March), was dominated by the juveniles of marine taxa that used the estuary as a nursery area. A striking feature of the above community was the decline in fish abundance with increasing river input, with flow values >100 m3 s−1 leading to increased loss of species from the system. This decline was linked to the lack of saline intrusion into the estuary and increased freshwater flooding through the system. 相似文献
17.
Aims: To assess the contribution of ozone to lethality of Salmonella enterica serovar Enteritidis in experimentally inoculated whole shell eggs that are sequentially treated with heat and gaseous ozone in pilot-scale equipment.
Methods and Results: Whole shell eggs were inoculated with small populations of Salmonella Enteritidis (8·5 × 104 –2·4 × 105 CFU per egg) near the egg vitelline membrane. Eggs were subjected to immersion heating (57°C for 21 min), ozone treatment (vacuum at 67·5 kPa, followed by ozonation at a maximum concentration of approx. 140 g ozone m−3 and 184–198 kPa for 40 min) or a combination of both treatments. Survivors were detected after an enrichment process or enumerated using modified most probable number technique. Ozone, heat and combination treatments inactivated 0·11, 3·1 and 4·2 log Salmonella Enteritidis per egg, respectively.
Conclusions: Sequential application of heat and gaseous ozone was significantly more effective than either heat or ozone alone. The demonstrated synergy between these treatment steps should produce safer shell eggs than the heat treatment alone.
Significance and Impact of the Study: Shell eggs are the most common vehicle for human infection by Salmonella Enteritidis. Many cases of egg-related salmonellosis are reported annually despite efforts to reduce contamination, including thermal pasteurization of shell eggs and egg products. Treatment with ozone-based combination should produce shell eggs safer than those treated with heat alone. 相似文献
Methods and Results: Whole shell eggs were inoculated with small populations of Salmonella Enteritidis (8·5 × 10
Conclusions: Sequential application of heat and gaseous ozone was significantly more effective than either heat or ozone alone. The demonstrated synergy between these treatment steps should produce safer shell eggs than the heat treatment alone.
Significance and Impact of the Study: Shell eggs are the most common vehicle for human infection by Salmonella Enteritidis. Many cases of egg-related salmonellosis are reported annually despite efforts to reduce contamination, including thermal pasteurization of shell eggs and egg products. Treatment with ozone-based combination should produce shell eggs safer than those treated with heat alone. 相似文献
18.
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
19.
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
20.
Romano A Perello MC de Revel G Lonvaud-Funel A 《Journal of applied microbiology》2008,104(6):1577-1585
Aims: Brettanomyces / Dekkera bruxellensis is a particularly troublesome wine spoilage yeast. This work was aimed at characterizing its behaviour in terms of growth and volatile compound production in red wine.
Methods and Results: Sterile red wines were inoculated with 5 × 103 viable cells ml−1 of three B. bruxellensis strains and growth and volatile phenol production were followed for 1 month by means of plate counts and gas chromatography-mass spectrometry (GC-MS) respectively. Maximum population levels generally attained 106 –107 colony forming units (CFU) ml−1 and volatile phenol concentrations ranged from 500 to 4000 μg l−1 . Brettanomyces bruxellensis multiplication was also accompanied by the production of organic acids (from C2 to C10 ), short chain acid ethyl-esters and the 'mousy off-flavour' component 2-acetyl-tetrahydropyridine.
Conclusions: Different kinds of 'Brett character' characterized by distinct metabolic and sensory profiles can arise in wine depending on the contaminating strain, wine pH and sugar content and the winemaking stage at which contamination occurs.
Significance and Impact of the Study: We identified new chemical markers that indicate wine defects caused by B. bruxellensis. Further insight was provided into the role of some environmental conditions in promoting wine spoilage. 相似文献
Methods and Results: Sterile red wines were inoculated with 5 × 10
Conclusions: Different kinds of 'Brett character' characterized by distinct metabolic and sensory profiles can arise in wine depending on the contaminating strain, wine pH and sugar content and the winemaking stage at which contamination occurs.
Significance and Impact of the Study: We identified new chemical markers that indicate wine defects caused by B. bruxellensis. Further insight was provided into the role of some environmental conditions in promoting wine spoilage. 相似文献