REDUCTION OF EXOGENOUS FERRIC IRON BY A SURFACE-ASSOCIATED FERRIC REDUCTASE OF LISTERIA SPP
REDUCTION OF EXOGENOUS FERRIC IRON BY A SURFACE-ASSOCIATED FERRIC REDUCTASE OF LISTERIA SPP
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DOI：
10.1099/13500872-141-8-1985
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发表时间：
1995-08-01
期刊：
影响因子：
--
通讯作者：
BOYCHUK, I
中科院分区：
文献类型：
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作者：
DENEER, HG;HEALEY, V;BOYCHUK, I
研究了革兰氏阳性食源性病原菌单核增生李斯特菌对外源性铁的还原作用。利用含亚铁螯合剂铁锌的实验，我们发现单核增生乳杆菌的完整细胞，当暴露于铁中时，能够迅速还原并将铁溶解为亚铁形式。只有在细菌与铁源直接接触后才会发生还原。许多不同的铁螯合物，包括转铁蛋白和乳铁蛋白结合的铁、血红蛋白、铁蛋白和铁载体络合的铁，可以被还原。参考菌株和临床分离的单核增生乳杆菌以及所有其他种类的李斯特菌均表达铁还原酶活性，尽管观察到显著的数量差异。在单核增生乳杆菌中，铁还原酶的表达不受细菌生长阶段的影响，也不受生长培养基中铁的存在或缺乏的影响。然而，在厌氧生长的细菌和在降低ph的培养基中培养时，表达量大大降低。此外，在低温下生长的细菌比在高温下生长的细胞表现出更大的铁还原酶活性。表面相关的铁还原酶系统可能是一般铁清除机制的一个组成部分，它可以被生长在各种环境中的李斯特菌所利用。
The reduction of exogenous ferric iron by Listeria monocytogenes, a Gram-positive food-borne pathogen, was investigated. Using an assay incorporating the ferrous iron chelator ferrozine, we showed that intact cells of L. monocytogenes, when exposed to ferric iron, were able to rapidly reduce and solubilize the iron to the ferrous form. Reduction occurred only after direct contact between the bacteria and the iron source. A number of different ferric iron chelates, including transferrin and lactoferrin-bound iron, haemoglobin, ferritin, and iron complexed to siderophores, could be reduced. The ferric reductase activity was expressed by both reference strains and clinical isolates of L. monocytogenes and by all other species of Listeria, although significant quantitative differences were observed. In L. monocytogenes, the expression of ferric reductase was not affected by the growth phase of the bacteria nor by the presence or absence of iron in the growth medium. However, expression was greatly reduced in bacteria grown anaerobically and when cultured in media of reduced pH. In addition, bacteria grown at a cold temperature displayed greater ferric reductase activity than cells grown at higher temperatures. A surface-associated ferric reductase system may be one component of a general iron scavenging mechanism which can be used by Listeria growing in a variety of environments.