The polymerase chain reaction (PCR) was used for the detection of toxigenic Clostridium difficile (Cd). A primer pair derived from non-repeating sequences of the toxin A gene were used to amplify a 306 bp DNA fragment...The polymerase chain reaction (PCR) was used for the detection of toxigenic Clostridium difficile (Cd). A primer pair derived from non-repeating sequences of the toxin A gene were used to amplify a 306 bp DNA fragment. Amplified products were visualized by polyacrylamide gel electrophoresis followed by ethidium bromide staining. All 19 strains of toxigenic Cd generated single specific amplified DNA. In contrast, none of the 8 strains of non-toxigenic Cd, 2 strains of C. sordelli and 2 strains of E. coli gave positive results. After the detected DNA of toxigenic Cd was diluted to 0.5ng, the polymerase chain reaction assays were still positive. The results demonstrate that polymerase chain reaction is a simple, rapid, specific and sensitive method for the detection of toxigenic Cd and could be used for the direct detection of Cd in feces samples.展开更多
In this study, the effects of the storage duration of coffee cherries after harvest before putting out for sun drying on the kinetics of drying, fungi development and the variation of physicochemical content were eval...In this study, the effects of the storage duration of coffee cherries after harvest before putting out for sun drying on the kinetics of drying, fungi development and the variation of physicochemical content were evaluated. The results showed that the longer coffee cherries were stored after harvest before putting out for sun drying, the quicker they dried. Indeed, the drying durations were 19, 16, 12, 10, 7 days respectively for coffee cherries put out for sun drying at the day of harvest, the second, the fourth, the sixth and the eighth day after harvest. However, this storage of the cherries after harvest before putting out for sun drying led to the increasing to the infection of cherries by fungi. Indeed, samples of more contaminated inside were those from the lots of cherries stored 8 days after harvest before putting out for sun drying with 55.55% of the samples infected with a percentage of infected beans between 10% and 50%, and 44.45% of the samples were infected with a percentage of infected beans between 50% and 100%. Furthermore, those put out for sun drying at the day of harvest were free inside by fungi. Among the fungi isolated, toxigenic species was found. However, no relationship between the frequencies of ochratoxin A producing strains isolated and the storage duration of the cherries after harvest before putting out for sun drying was noted. This storage of the cherries after harvest before putting out for sun drying also led to the acidification of the cherries (pH = 5.27 - 3.6) and the degradation of their chlorogenic acids content (12.58% - 10.30%) while for their caffeine content (2.53% - 2.55%). No significant difference was observed about the storage duration of the cherries after harvest before putting out for sun drying.展开更多
Clostridium difficile is a Gram positive rod-shaped bacterium that produces two major toxins, A and B. The detection of the organism and its toxins has been widely carried out using specialized Enzyme-Linked Immunosor...Clostridium difficile is a Gram positive rod-shaped bacterium that produces two major toxins, A and B. The detection of the organism and its toxins has been widely carried out using specialized Enzyme-Linked Immunosorbent Assay (ELISA) kits;however these generally have been unsuccessful in identifying all Clostridium difficile positive samples. In this study, fifteen clinically symptomatic patients from three of the five major regional hospitals in Trinidad were investigated for Clostridium difficile infections. Stool samples were assessed by ELISA and cultured isolates were characterized using agar dilution antibiotic sensitivity assays, conventional Polymerase Chain Reaction (PCR), DNA sequencing and phylogenetic analysis of toxin A and B genes. All 15 patient stool samples and isolates were positive for toxigenic Clostridium difficile via ELISA and PCR respectively. All isolates were positive for the housekeeping tpi and Toxin B genes by PCR but only three of these were positive for the Toxin A gene. The Toxin B gene sequences showed 100% similarity levels among isolates while the Toxin A gene sequences showed 99% similarity among isolates. Phylogenetic analysis showed that the strains isolated in Trinidad most likely belonged to the same strain/group. Agar dilution sensitivity tests showed highest susceptibility to Pipercillin/Tazobactam and Meropenem (87%) and the highest resistance was seen with Cefotaxime in 93%. These results indicate that similar virulent strains of C. difficile are present in the Trinidad population and that pathogenic strains are more likely to be susceptible to Pipercillin/Tazobactam and Meropenem.展开更多
This study shows that the main cause of Fusarium head blight of spelt was F. poae. In 2007 deoxynivalenol was found up to 0.27 mg/kg in 2 of 18 samples of winter spelt kernels from organic farms. Also in 3 samples T-2...This study shows that the main cause of Fusarium head blight of spelt was F. poae. In 2007 deoxynivalenol was found up to 0.27 mg/kg in 2 of 18 samples of winter spelt kernels from organic farms. Also in 3 samples T-2 toxin was found in amount below 0.075 mg/kg. Aflatoxins and ochratoxin A were not found in kernels. Among nine of the examined samples of winter spelt in 2008, DON was identified in all samples （up to 0.31 mg/kg）, while T-2 toxin, aflatoxins and OTA were not found. Among twenty of the examined cultivars of winter spelt, deoxynivalenol was identified in 6 samples （up to 0.3 mg/kg）, T-2 toxin was identified in one sample in very low amount （below 75 μg/kg） while aflatoxins and ochratoxin A were not found. Deoxynivalenol was found in following winter spelt cultivars： T. spelta L. album, T. spelta BG, T. spelta BG 1166, T. spelta, Schwabenspelz and Franckenkorn. T-2 toxin was identified in T. spelta L. album BG 31. Among 13 products from spelt, DON was detected in 1 sample, OTA in 1 sample and zearalenone in 1 sample, T-2 toxins and aflatoxins were not found.展开更多
【目的】明确不同省(自治区)引起玉米穗腐病的禾谷镰孢复合种(Fusarium graminearum species complex,FGSC)的毒素化学型和它们之间的遗传差异以及亲缘关系。【方法】选用根据基因Tri13和Tri3序列设计的特异性引物分析来自11个省(自治区...【目的】明确不同省(自治区)引起玉米穗腐病的禾谷镰孢复合种(Fusarium graminearum species complex,FGSC)的毒素化学型和它们之间的遗传差异以及亲缘关系。【方法】选用根据基因Tri13和Tri3序列设计的特异性引物分析来自11个省(自治区)的92株禾谷镰孢复合种菌株的毒素化学型;从100条哥伦比亚大学(UBC)开发的通用引物中筛选出13条扩增条带丰富、重复性好、信号强、背景清晰的引物,利用筛选出的引物对供试菌株进行ISSR-PCR扩增,使用Popgen32软件计算多态性位点百分率、Shannon’s多样性指数、群体间的遗传距离和遗传相似性;依据Nei’s遗传距离,利用NTsys2.10e软件进行UPGMA聚类分析,并构建供试菌株的聚类图。【结果】供试的92株禾谷镰孢复合种菌株的产毒素化学型有4种:DON、15-ADON、DON+15-ADON和NIV+15-ADON。其中产生DON和15-ADON的菌株分别为1株和20株;同时产生15-ADON和NIV的有1株;同时产生15-ADON和DON的有55株。筛选出的13条引物对所有供试菌株进行PCR扩增,共获得102条带,其中多态性条带101条,多态性比率为99.02%,平均每条引物产生条带为7.85条。在群体平均水平上,基因多样性指数(H)为0.3129,Shannon’s的信息指数(I)为0.4774,表明禾谷镰孢复合种存在较高的遗传多样性水平;不同地理种群间,各群体的遗传多样性水平具有一定差异,河北、山西、黑龙江和吉林种群遗传多样性最高,安徽和河南种群最低。地理种群间的基因分化系数(Gst)为0.2722,说明不同地理种群间存在一定的遗传变异,但大部分遗传变异(72.78%)发生在种群内。遗传分化系数估算的基因流值Nm=1.3372(>1),表明不同地理种群间存在一定的基因流动;遗传关系结果表明河北、山西、黑龙江、吉林、辽宁、内蒙古和甘肃菌株群体间亲缘关系较近,山东、江苏、河南和安徽菌株间亲缘关系较近,安徽和内蒙古菌株间的亲缘关系最远。聚类分析显示所有菌株相似系数为0.43—0.95。在相似系数为0.43时,所有菌株分成2大类群,Group 1包括4株北方春播区菌株(吉林、山西和河北张家口),不产生NIV和DON;Group 2由余下的88株菌株构成,产生的毒素类型主要为DON和15-ADON,其来源于北方春播区(山西、黑龙江、吉林、辽宁、甘肃和河北张家口、唐山)和黄淮海夏播区(河北石家庄、河南、山东、江苏和安徽),在相似系数为0.664时,各类群分成不同的亚群,亚群的结果与菌株来源有一定的相关性。聚类分析结果和毒素化学型分析显示,同一地理种群的菌株多数聚在一起,个别菌株分散到不同的分支上。【结论】北方春播区和黄淮海夏播区的禾谷镰孢复合种主要的毒素化学型为DON和15-ADON。引起玉米穗腐病的禾谷镰孢复合种菌株群体内存在丰富的遗传变异,不同地理种群间存在一定的基因交流,遗传多样性与地理来源有关。展开更多
文摘The polymerase chain reaction (PCR) was used for the detection of toxigenic Clostridium difficile (Cd). A primer pair derived from non-repeating sequences of the toxin A gene were used to amplify a 306 bp DNA fragment. Amplified products were visualized by polyacrylamide gel electrophoresis followed by ethidium bromide staining. All 19 strains of toxigenic Cd generated single specific amplified DNA. In contrast, none of the 8 strains of non-toxigenic Cd, 2 strains of C. sordelli and 2 strains of E. coli gave positive results. After the detected DNA of toxigenic Cd was diluted to 0.5ng, the polymerase chain reaction assays were still positive. The results demonstrate that polymerase chain reaction is a simple, rapid, specific and sensitive method for the detection of toxigenic Cd and could be used for the direct detection of Cd in feces samples.
文摘In this study, the effects of the storage duration of coffee cherries after harvest before putting out for sun drying on the kinetics of drying, fungi development and the variation of physicochemical content were evaluated. The results showed that the longer coffee cherries were stored after harvest before putting out for sun drying, the quicker they dried. Indeed, the drying durations were 19, 16, 12, 10, 7 days respectively for coffee cherries put out for sun drying at the day of harvest, the second, the fourth, the sixth and the eighth day after harvest. However, this storage of the cherries after harvest before putting out for sun drying led to the increasing to the infection of cherries by fungi. Indeed, samples of more contaminated inside were those from the lots of cherries stored 8 days after harvest before putting out for sun drying with 55.55% of the samples infected with a percentage of infected beans between 10% and 50%, and 44.45% of the samples were infected with a percentage of infected beans between 50% and 100%. Furthermore, those put out for sun drying at the day of harvest were free inside by fungi. Among the fungi isolated, toxigenic species was found. However, no relationship between the frequencies of ochratoxin A producing strains isolated and the storage duration of the cherries after harvest before putting out for sun drying was noted. This storage of the cherries after harvest before putting out for sun drying also led to the acidification of the cherries (pH = 5.27 - 3.6) and the degradation of their chlorogenic acids content (12.58% - 10.30%) while for their caffeine content (2.53% - 2.55%). No significant difference was observed about the storage duration of the cherries after harvest before putting out for sun drying.
文摘Clostridium difficile is a Gram positive rod-shaped bacterium that produces two major toxins, A and B. The detection of the organism and its toxins has been widely carried out using specialized Enzyme-Linked Immunosorbent Assay (ELISA) kits;however these generally have been unsuccessful in identifying all Clostridium difficile positive samples. In this study, fifteen clinically symptomatic patients from three of the five major regional hospitals in Trinidad were investigated for Clostridium difficile infections. Stool samples were assessed by ELISA and cultured isolates were characterized using agar dilution antibiotic sensitivity assays, conventional Polymerase Chain Reaction (PCR), DNA sequencing and phylogenetic analysis of toxin A and B genes. All 15 patient stool samples and isolates were positive for toxigenic Clostridium difficile via ELISA and PCR respectively. All isolates were positive for the housekeeping tpi and Toxin B genes by PCR but only three of these were positive for the Toxin A gene. The Toxin B gene sequences showed 100% similarity levels among isolates while the Toxin A gene sequences showed 99% similarity among isolates. Phylogenetic analysis showed that the strains isolated in Trinidad most likely belonged to the same strain/group. Agar dilution sensitivity tests showed highest susceptibility to Pipercillin/Tazobactam and Meropenem (87%) and the highest resistance was seen with Cefotaxime in 93%. These results indicate that similar virulent strains of C. difficile are present in the Trinidad population and that pathogenic strains are more likely to be susceptible to Pipercillin/Tazobactam and Meropenem.
文摘This study shows that the main cause of Fusarium head blight of spelt was F. poae. In 2007 deoxynivalenol was found up to 0.27 mg/kg in 2 of 18 samples of winter spelt kernels from organic farms. Also in 3 samples T-2 toxin was found in amount below 0.075 mg/kg. Aflatoxins and ochratoxin A were not found in kernels. Among nine of the examined samples of winter spelt in 2008, DON was identified in all samples （up to 0.31 mg/kg）, while T-2 toxin, aflatoxins and OTA were not found. Among twenty of the examined cultivars of winter spelt, deoxynivalenol was identified in 6 samples （up to 0.3 mg/kg）, T-2 toxin was identified in one sample in very low amount （below 75 μg/kg） while aflatoxins and ochratoxin A were not found. Deoxynivalenol was found in following winter spelt cultivars： T. spelta L. album, T. spelta BG, T. spelta BG 1166, T. spelta, Schwabenspelz and Franckenkorn. T-2 toxin was identified in T. spelta L. album BG 31. Among 13 products from spelt, DON was detected in 1 sample, OTA in 1 sample and zearalenone in 1 sample, T-2 toxins and aflatoxins were not found.
