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The nature of water within bacterial spores: protecting life in extreme environments

机译：细菌孢子中水的性质：保护极端环境下的生命

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The bacterial spore is a formidable container of life, protecting the vital contents from chemical attack, antimicrobial agents, heat damage, UV light degradation, and water dehydration. The exact role of the spore components remains in dispute. Nevertheless, water molecules are important in each of these processes. The physical state of water within the bacterial spore has been investigated since the early 1930's. The water is found two states, free or bound, in two different areas, core and non-core. It is established that free water is accessible to diffuse and exchange with deuterated water and that the diffusible water can access all areas of the spore. The presence of bound water has come under recent scrutiny and has been suggested the water within the core is mobile, rather than bound, based on the analysis of deuterium relaxation rates. Using an alternate method, deuterium quadrupole-echo spectroscopy, we are able to distinguish between mobile and immobile water molecules. In the absence of rapid motion, the deuterium spectrum of D_2O is dominated by a broad line, whose line shape is used as a characteristic descriptor of molecular motion. The deuterium spectrum of bacterial spores reveals three distinct features: the broad peak of immobilized water, a narrow line of water in rapid motion, and a signal of intermediate width. This third signal is assigned this peak from partially deuterated proteins with the spore in which N-H groups have undergone exchange with water deuterons to form N-D species. As a result of these observations, the nature of water within the spore requires additional explanation to understand how the spore and its water preserve life.
机译：细菌孢子是生命的强大容器，可保护重要内容物免受化学侵蚀，抗菌剂，热损伤，紫外线降解和水脱水。孢子成分的确切作用仍存在争议。然而，水分子在每个过程中都很重要。自1930年代初以来，已经研究了细菌孢子中水的物理状态。在核心和非核心两个不同的区域中发现了水的两个状态，自由状态或约束状态。已经确定游离水可以扩散和与氘化水交换，并且扩散水可以进入孢子的所有区域。结合水的存在已受到最近的审查，并已根据氘弛豫速率的分析表明，岩心中的水是流动的而不是结合的。使用另一种方法，氘四极回波光谱学，我们能够区分流动的水分子和固定的水分子。在没有快速运动的情况下，D_2O的氘谱以一条宽线为主，其线形用作分子运动的特征描述子。细菌孢子的氘光谱显示出三个不同的特征：固定水的宽峰，快速运动的水的窄线和中等宽度的信号。该第三信号从部分氘代蛋白质的孢子中获得该峰，在该孢子中，N-H基团已与水氘核交换形成N-D物质。这些观察的结果是，孢子中水的性质需要进一步解释，以了解孢子及其水如何维持生命。

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