Abstract:

The widely distributed genus Shewanella is famous for its capacity of reducing iron. The aim of this study is to decipher the behavioral change on Shewanella xiamenensis BC01 (SXM) under stress of organic solvents. The tolerance of SXM to organic solvents is related to the hydrophilicity of solvents. For methanol, ethanol, acetone and DMSO, the tolerance concentration for SXM is 5%, for n-propanol, isopropanol and tert-butanol, the tolerance concentration is 2%, while for n-butanol, the tolerance concentration is only 1%. The scanning electron microscopy revealed that cells were obviously stretched to at least 5 μm under n-propanol stress, and cells were shrunk to an average of less than 1 μm under n-butanol stress. Protein identification implied that TonB receptor, IucA family protein and iron containing dehydrogenase were down-regulating under propanol and butanol stress, and the enzymatic assay of ferric reductase was obviously dropped down. At the genetic level, the expression of mtrC gene related to electron transport increased by 147.6% under the stimulation of propanol. It would provide practical information on environmental stress and accelerate mechanism of stress in Shewanella geneus.

Key words: organic solvents, Shewanella, alcohol stress, iron reductase, biological engineering, protein, morphology

摘要：

以铁还原菌厦门希瓦氏菌Shewanella xiamenensis BC01（SXM）为研究对象，系统探究了SXM在不同有机溶剂胁迫下的行为变化。生长方面，SXM对有机溶剂的耐受性与其亲水性相关，甲醇、乙醇、丙酮及DMSO的耐受浓度可达5%，对异丙醇、丙醇及叔丁醇的耐受浓度为2%，对丁醇的耐受浓度仅为1%。形态方面，丙醇刺激下的SXM菌体被显著拉长为至少5 μm以上，而丁醇刺激下菌体则缩小至平均不足1 μm，且均为可逆变化；蛋白方面，在丙醇与丁醇刺激下，与铁代谢相关的TonB、IucA及含铁脱氢酶等蛋白表达量均下调，铁还原酶活性也被大幅抑制；基因层面，丙醇刺激下与电子传递相关的mtrC基因表达量提高147.6%。

关键词: 有机溶剂, 希瓦氏菌, 醇类应激, 铁还原酶, 生物工程, 蛋白质, 形态学