Khashe S, Janda J M
Division of Communicable Disease Control, California Department of Health Services, Berkeley 94704-1011, USA.
FEMS Microbiol Lett. 1996 Apr 1;137(2-3):141-6. doi: 10.1111/j.1574-6968.1996.tb08096.x.
Seventy-one strains of Citrobacter were screened for iron scavenging mechanisms by biologic and chemical assays. Essentially all citrobacteria (70/71) were found to elaborate enterobactin-like siderophores by both biologic and chemical assays, however only c. koseri (C. diversus) was found to produce aerobactin. The concentration of ethylenediamine di(o-hydroxyphenylacetic acid) (EDDA) required to inhibit the growth of individual Citrobacter strains by depleting free iron ranged from 250 micrograms/ml to 100 micrograms/ml. Iron utilization studies of selected citrobacter isolates indicated that hemin and hematin could reverse the effects of iron limitation on growth under iron-stressed conditions (1000 micrograms/ml of EDDA). Two C. koseri strains grown under iron-restricted conditions showed similar changes in their whole cell protein profiles including induction of high molecular mass proteins (72-83 kDa) which may play a role in iron acquisition under iron-stressed conditions. The collective results support an additional virulence-associated mechanism for C. koseri strains which may help explain the greater pathogenic potential this group has for causing serious extraintestinal disease in humans.
通过生物学和化学分析筛选了71株柠檬酸杆菌的铁清除机制。通过生物学和化学分析发现，基本上所有的柠檬酸杆菌（70/71）都能产生肠杆菌素样铁载体，然而，仅发现科氏柠檬酸杆菌（异型柠檬酸杆菌）能产生气杆菌素。通过耗尽游离铁来抑制单个柠檬酸杆菌菌株生长所需的乙二胺二（邻羟基苯乙酸）（EDDA）浓度范围为250微克/毫升至100微克/毫升。对选定的柠檬酸杆菌分离株的铁利用研究表明，在铁应激条件下（1000微克/毫升的EDDA），血红素和高铁血红素可以逆转铁限制对生长的影响。在铁限制条件下生长的两株科氏柠檬酸杆菌菌株在其全细胞蛋白质谱中显示出类似的变化，包括高分子量蛋白质（72-83 kDa）的诱导，这些蛋白质可能在铁应激条件下的铁获取中发挥作用。这些总体结果支持了科氏柠檬酸杆菌菌株的一种额外的毒力相关机制，这可能有助于解释该菌属在人类中引起严重肠外疾病的更大致病潜力。
