DEMONSTRATION OF EXOPOLYSACCHARIDE PRODUCTION BY ENTEROHEMORRHAGIC ESCHERICHIA-COLI
DEMONSTRATION OF EXOPOLYSACCHARIDE PRODUCTION BY ENTEROHEMORRHAGIC ESCHERICHIA-COLI
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DOI：
10.1007/bf01570076
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发表时间：
1992-07-01
影响因子：
2.6
通讯作者：
DOYLE, MP
中科院分区：
文献类型：
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作者：
JUNKINS, AD;DOYLE, MP
肠出血性大肠杆菌O 157：H7在室温下在山梨醇/麦康凯或马洛尼琼脂平板上生长时产生可见的粘粘菌落，表明产生胞外多糖（EPS）。27株野生型E. coliO 57：H7分离株产生足够的EPS，以在视觉上区分。在这些培养基上没有显示出可见的EPS产生的五种菌株中，有四种（80%）在含有较高盐浓度的培养基上确实产生了粘粘的菌落。糖醛酸比色法测定胞外多糖的产量表明，胞外多糖的产量受生长温度、气氛和培养基的影响。野生型E.大肠杆菌O 57：H7菌株932在37 ℃厌氧生长时产生最大量的EPS，而其质粒固化衍生物932 P在室温有氧生长时产生大量EPS。电子显微镜照片显示从细菌细胞表面延伸出的细而柔韧的纤维。在室温下有氧生长的菌株932 P的细胞完全包裹在厚的EPS基质中。纯化的EPS的化学分析显示，它是非常相似或相同的colanic酸。E.大肠杆菌O 57：H7在有利于高EPS产生的条件下比在抑制EPS产生的条件下生长时更好地粘附INT 407细胞。
Enterohemorrhagic Escherichia coli O157:H7 produces visibly slimy colonies when grown on Sorbitol/MacConkey or Maloney's agar plates at room temperature, indicative of exopolysaccharide (EPS) production. Eighteen of 27 (67%) wild-type E. coli O57:H7 isolates produced enough EPS to be visually distinguishable. Of five strains that showed no visible EPS production on these media, four (80%) did produce slimy colonies on media containing higher salt concentrations. Measurements of EPS production by colorimetric determination of uronic acid indicated that EPS production was affected by growth temperature, atmosphere, and medium. Wild-type E. coli O57:H7 strain 932 produced the greatest amounts of EPS when grown anaerobically at 37-degrees-C, whereas its plasmid-cured derivative 932P produced large quantities of EPS when grown aerobically at room temperature. Electron micrographs revealed thin, flexible fibers extending from the bacterial cell surface. Cells of strain 932P grown aerobically at room temperature were completely encased in a thick EPS matrix. Chemical analysis of purified EPS revealed that it is very similar or identical to colanic acid. E. coli O57:H7 adheres better to INT 407 cells when grown under conditions that favor high EPS production than when grown under conditions that repress EPS production.