The genome of the enterohemorrhagic Escherichia coli O157∶H7 EDL933 contains 177 “O”-islands (OIs). To study their potential contribution to the O157-specific pathogenicity, we surveyed the distribution of 22 OIs b...The genome of the enterohemorrhagic Escherichia coli O157∶H7 EDL933 contains 177 “O”-islands (OIs). To study their potential contribution to the O157-specific pathogenicity, we surveyed the distribution of 22 OIs by PCR and DNA hybridization in 17 isolates of Shiga toxin producing (Stx-positive) E.coli O157∶H7, and compared with their distribution in 21 isolates of Stx-negative E.coli O157 and 21 isolates of non-O157 enteric pathogens. Fourteen of 22 OIs were present in non-O157 entericpathogens analyzed. Eight of 22 OIs were found only in the 17 Shiga toxin- (Stx) positive E.coli O157∶H7 isolates, but they were absent from the 21 Stx-negative E.coli O157∶NM and O157︰Hund isolates tested. Among the 8 OIs, only OI43 or OI48 were exclusively detected in Stx-positive E.coli O157∶H7, absent from neither of Stx-negative E.coli O157 and non-O157 enteric pathogens, such as Salmonella, Shigella, Citrobacter, Vibrio cholera, enteropathogenic E.coli (EPEC), enteroadherent E.coli (EAEC), enteroinvasive E.coli (EIEC) and enterotoxingenic E.coli (ETEC). The OI43 and OI48 are 83 kb in size and identical in DNA sequences, which encode genes for urease, tellurite resistance and adherence. By analyzing their junction genes with PCR and DNA hybridization, we found that 21 Chinese isolates have OI48 only. However, for 7 Japanese patient isolates, 4 have OI43 and 3 have OI48; for American isolates, 2 have both of OI43 and OI48, 2 have OI48 only. These data confirmed the highly plasticity of the pathogenic E.coli genome. The unique presence of OI43/OI48 in Stx-positive E.coli O157∶H7 denotes its critical role in the pathogenicity specific to this pathogen.展开更多
将免疫荧光纳米标记技术与激光共聚焦显微成像方法相结合,发展了一种基于二氧化硅荧光纳米颗粒和核酸染料SYBR Green Ⅰ的双色显微成像技术用于大肠杆菌O157∶H7的检测.采用联吡啶钌(RuBpy)二氧化硅荧光纳米颗粒对羊抗大肠杆菌O157∶H7...将免疫荧光纳米标记技术与激光共聚焦显微成像方法相结合,发展了一种基于二氧化硅荧光纳米颗粒和核酸染料SYBR Green Ⅰ的双色显微成像技术用于大肠杆菌O157∶H7的检测.采用联吡啶钌(RuBpy)二氧化硅荧光纳米颗粒对羊抗大肠杆菌O157∶H7抗体进行修饰,基于抗体-抗原相互作用实现了其对目标大肠杆菌O157∶H7的特异性标记;同时以核酸染料SYBR GreenⅠ对细菌进行染色,将细菌和纳米颗粒团聚体区分开,实现了对大肠杆菌O157∶H7的双色标记,并通过激光共聚焦显微镜进行免分离的荧光成像检测.结果表明,该方法可用于缓冲溶液体系和混合细菌样品中目标大肠杆菌O157∶H7的特异性检测,在仅含5%目标菌的混合样品中仍能观察到具有明显黄色荧光的大肠杆菌O157∶H7,且整个检测步骤包括样品预处理可在3 h内完成.该方法则具有较好的灵敏度,可检出2.6×103 Cell/mL的目标细菌样品.若采用针对其它病原菌细胞壁抗原的特异性抗体,则有望发展成为一种通用技术用于多种病原菌的快速和灵敏检测.展开更多
Escherichia coli O157:H7 is one of the major foodborne pathogenic bacterial that cause infectious diseases in humans.The previous found that a combination of kojic acid and tea polyphenols exhibited better activity ag...Escherichia coli O157:H7 is one of the major foodborne pathogenic bacterial that cause infectious diseases in humans.The previous found that a combination of kojic acid and tea polyphenols exhibited better activity against E.coli O157:H7 than using either alone.This study aimed to explore responses underlying the antibacterial mechanisms of kojic acid and tea polyphenols from the gene level.The functional enrichment analysis by comparing kojic acid and tea polyphenols individually or synergistically against E.coli O157:H7 found that acid resistance systems in kojic acid were activated,and the cell membrane and genomic DNA were destructed in the cells,resulting in“oxygen starvation”.The oxidative stress response triggered by tea polyphenols inhibited both sulfur uptake and the synthesis of ATP,which affected the bacteria's life metabolic process.Interestingly,we found that kojic acid combined with tea polyphenols hindered the uptake of iron that played an essential role in the synthesis of DNA,respiration,tricarboxylic acid cycle.The results suggested that the iron uptake pathways may represent a novel approach for kojic acid and tea polyphenols synergistically against E.coli O157:H7 and provided a theoretical basis for bacterial pathogen control in the food industry.展开更多
基金This work was supported by the Basic Research Program from Ministry of Science and Technology,China (G1999054101 to J.Xu.) and PRA program from AFCRST (B99 03) to LFW
文摘The genome of the enterohemorrhagic Escherichia coli O157∶H7 EDL933 contains 177 “O”-islands (OIs). To study their potential contribution to the O157-specific pathogenicity, we surveyed the distribution of 22 OIs by PCR and DNA hybridization in 17 isolates of Shiga toxin producing (Stx-positive) E.coli O157∶H7, and compared with their distribution in 21 isolates of Stx-negative E.coli O157 and 21 isolates of non-O157 enteric pathogens. Fourteen of 22 OIs were present in non-O157 entericpathogens analyzed. Eight of 22 OIs were found only in the 17 Shiga toxin- (Stx) positive E.coli O157∶H7 isolates, but they were absent from the 21 Stx-negative E.coli O157∶NM and O157︰Hund isolates tested. Among the 8 OIs, only OI43 or OI48 were exclusively detected in Stx-positive E.coli O157∶H7, absent from neither of Stx-negative E.coli O157 and non-O157 enteric pathogens, such as Salmonella, Shigella, Citrobacter, Vibrio cholera, enteropathogenic E.coli (EPEC), enteroadherent E.coli (EAEC), enteroinvasive E.coli (EIEC) and enterotoxingenic E.coli (ETEC). The OI43 and OI48 are 83 kb in size and identical in DNA sequences, which encode genes for urease, tellurite resistance and adherence. By analyzing their junction genes with PCR and DNA hybridization, we found that 21 Chinese isolates have OI48 only. However, for 7 Japanese patient isolates, 4 have OI43 and 3 have OI48; for American isolates, 2 have both of OI43 and OI48, 2 have OI48 only. These data confirmed the highly plasticity of the pathogenic E.coli genome. The unique presence of OI43/OI48 in Stx-positive E.coli O157∶H7 denotes its critical role in the pathogenicity specific to this pathogen.
基金supported by National Natural Science Foundation of China(31972021)R&D Projects in Key Areas of Guangdong Province(2019B020212003)+4 种基金the Science and Technology Program of Guangzhou,China(202206010177)Guangdong key research and development program(2021B0202060001)Foshan and agricultural academy cooperation projectGuangdong Modern Agriculture project(2022KJ117)Aquatic Products Center Project of GAAS。
文摘Escherichia coli O157:H7 is one of the major foodborne pathogenic bacterial that cause infectious diseases in humans.The previous found that a combination of kojic acid and tea polyphenols exhibited better activity against E.coli O157:H7 than using either alone.This study aimed to explore responses underlying the antibacterial mechanisms of kojic acid and tea polyphenols from the gene level.The functional enrichment analysis by comparing kojic acid and tea polyphenols individually or synergistically against E.coli O157:H7 found that acid resistance systems in kojic acid were activated,and the cell membrane and genomic DNA were destructed in the cells,resulting in“oxygen starvation”.The oxidative stress response triggered by tea polyphenols inhibited both sulfur uptake and the synthesis of ATP,which affected the bacteria's life metabolic process.Interestingly,we found that kojic acid combined with tea polyphenols hindered the uptake of iron that played an essential role in the synthesis of DNA,respiration,tricarboxylic acid cycle.The results suggested that the iron uptake pathways may represent a novel approach for kojic acid and tea polyphenols synergistically against E.coli O157:H7 and provided a theoretical basis for bacterial pathogen control in the food industry.
