3 SEPARATE CLASSES OF BACTERIAL ICE NUCLEATION STRUCTURES
3 SEPARATE CLASSES OF BACTERIAL ICE NUCLEATION STRUCTURES
复制标题
DOI：
10.1128/jb.172.5.2521-2526.1990
复制
发表时间：
1990-05-01
影响因子：
3.2
通讯作者：
KOZLOFF, LM
中科院分区：
文献类型：
--
作者：
TURNER, MA;ARELLANO, F;KOZLOFF, LM
对暴露在不同细菌表面的冰核结构的研究表明，这些细胞上有三种主要的相关但化学上不同的结构类型。首先，考察了冰+电池成核过冷D2O的能力，发现这种能力(相对于同一电池成核过冷H2O的能力)表现出三种特征的成核模式。最罕见的结构被称为A类，只在培养物中的一小部分细胞上发现，在-4.4摄氏度以上的温度下形成H2O，是过冷D2O的有效成核剂。第二类结构，称为B类，在电池的较大部分上被发现，成核H2O在-4.8℃到-5.7℃之间，是过冷D2O的相对较差的成核剂。几乎所有的细胞都有C类结构，并在-7.6℃或更低的温度下成核。这三类结构的区别还在于它们对低浓度的可溶于水的有机溶剂，如二氧六环或二甲基亚砜的敏感性。根据特定的细菌菌株，将这些溶剂添加到细菌悬浮液中会使A类结构的成核活性降低1000倍或更多。在同一培养条件下，B类结构的成核活性对这些化合物具有很强的抗性，仅降低了20%~40%。C类结构比B类结构更敏感，成核活性降低了70~90%。最后，考察了这三类结构的pH敏感性。在pH 4.5或更低的缓冲液中，A类结构被破坏，但在较高的pH值时，A类结构稳定。B类结构对酸性缓冲液不太敏感，但在pH 5.5或更低时被破坏，在较高的pH值下稳定。然而，在PHS为3.5到9.0的缓冲液中孵育不影响C类结构。对这三类材料的实际形核结构提出了建议。
Studies of the properties of the ice nucleation structure exposed on the surfaces of various bacteria such as Pseudomonas syringae, Erwinia herbicola, or various strains of Ice+ recombinant Escherichia coli have shown that there are clearly three major related but chemically distinct types of structures on these cells. First, the ability of Ice+ cells to nucleate super-cooled D2O has been examined, and it has been found that this ability (relative to the ability of the same cells to nucleate super-cooled H2O) exhibited three characteristic nucleating patterns. The rarest structure, called class A, is found on only a small fraction of cells in a culture, nucleates H2O at temperatures above -4.4.degree.C, and is an effective nucleator of super-cooled D2O. A second class of structure, called class B, is found on a larger portion of the cells, nucleates H2O between -4.8 and -5.7.degree.C, and is a relatively poor nucleator of super-cooled D2O. The class C structure is found on almost all cells and nucleates at -7.6.degree.C or colder. These three classes of structures were also differentiated by their sensitivities to low concentrations of water-miscible organic solvents such as dioxane or dimethyl sulfoxide. Depending on the specific bacterial strain, the addition of these solvents to bacterial suspensions lowered the nucleation activity of the class A structure by 1,000-fold or more. The nucleation activities of class B structures in the same culture were highly resistant to these compounds and were lowered only by 20 to 40%. The class C structures were more sensitive than Class B structures were, and the nucleation activities decreased 70 to 90%. Finally, the pH sensitivity of these three classes of structures was examined. The class A structure was destroyed in buffers at pH 4.5 or lower but was stable in buffers at higher pHs. The class B structure was less sensitive to acidic buffers but was destroyed at pH 5.5 or lower and was stable at higher pHs. However, the class C structure was unaffected by incubation in buffers with pHs of 3.5 to 9.0. Suggestions for the actual nucleation structures of the three classes are proposed.