Diarra M S, Dolence J A, Dolence E K, Darwish I, Miller M J, Malouin F, Jacques M
Departement de Microbiologie, Faculte de Medecine, Universite Laval, Sainte-Foy, Quebec, Canada.
Appl Environ Microbiol. 1996 Mar;62(3):853-9. doi: 10.1128/aem.62.3.853-859.1996.
Siderophores bind ferric ions and are involved in receptor-specific iron transport into bacteria. Six types of siderophores were tested against strains representing the 12 different serotypes of Actinobacillus pleuropneumoniae. Ferrichrome and bis-catechol-based siderophores showed strong growth-promoting activities for A. pleuropneumoniae in a disk diffusion assay. Most strains of A. pleuropneumoniae tested were able to use ferrichrome (21 of 22 or 95%), ferrichrome A (20 of 22 or 90%), and lysine-based bis-catechol (20 of 22 or 90%), while growth of 36% (8 of 22) was promoted by a synthetic hydroxamate, N5-acetyl-N5-hydroxy-L-ornithine tripeptide. A. pleuropneumoniae serotype 1 (strain FMV 87-682) and serotype 5 (strain 2245) exhibited a distinct yellow halo around colonies on Chrome Azurol S agar plates, suggesting that both strains can produce an iron chelator (siderophore) in response to iron stress. The siderophore was found to be neither a phenolate nor a hydroxamate by the chemical tests of Arnow and Csaky, respectively. This is the first report demonstrating the production of an iron chelator and the use of exogenous siderophores by A. pleuropneumoniae. A spermidine-based bis-catechol siderophore conjugated to a carbacephalosporin was shown to inhibit growth of A. pleuropneumoniae. A siderophore-antibiotic-resistant strain was isolated and shown to have lost the ability to use ferrichrome, synthetic hydroxamate, or catechol-based siderophores when grown under conditions of iron restriction. This observation indicated that a common iron uptake pathway, or a common intermediate, for hydroxamate- and catechol-based siderophores may exist in A. pleuropneumoniae.
铁载体可结合铁离子，并参与将受体特异性铁转运至细菌体内。针对代表胸膜肺炎放线杆菌12种不同血清型的菌株，测试了六种类型的铁载体。在纸片扩散试验中，高铁色素和基于双儿茶酚的铁载体对胸膜肺炎放线杆菌表现出很强的促生长活性。所测试的大多数胸膜肺炎放线杆菌菌株能够利用高铁色素（22株中的21株，即95%）、高铁色素A（22株中的20株，即90%）和基于赖氨酸的双儿茶酚（22株中的20株，即90%），而一种合成异羟肟酸N5-乙酰-N5-羟基-L-鸟氨酸三肽可促进36%（22株中的8株）菌株的生长。胸膜肺炎放线杆菌血清型1（菌株FMV 87-682）和血清型5（菌株2245）在铬天青S琼脂平板上的菌落周围呈现出明显的黄色晕圈，这表明这两种菌株在铁胁迫下均可产生一种铁螯合剂（铁载体）。通过分别进行的阿诺氏试验和恰基试验的化学测试发现，该铁载体既不是酚盐也不是异羟肟酸。这是首次报道胸膜肺炎放线杆菌产生铁螯合剂以及利用外源性铁载体的研究。一种与碳头孢菌素缀合的基于亚精胺的双儿茶酚铁载体可抑制胸膜肺炎放线杆菌的生长。分离出了一株对铁载体-抗生素耐药的菌株，结果表明，在铁限制条件下培养时，该菌株丧失了利用高铁色素、合成异羟肟酸或基于儿茶酚的铁载体的能力。这一观察结果表明，胸膜肺炎放线杆菌中可能存在一条针对基于异羟肟酸和儿茶酚的铁载体的共同铁摄取途径或共同中间体。
