Endospores formed by Bacillus, Clostridia, and related genera are encased in a protein shell called the coat. In many species, including B. subtilis, the coat is the outermost spore structure, and in other species, such as the pathogenic organisms B. anthracis and B. cereus, the spore is encased in an additional layer called the exosporium. Both the coat and the exosporium have roles in protection of the spore and in its environmental interactions. Assembly of both structures is a function of the mother cell, one of two cellular compartments of the developing sporangium. Studies in B. subtilis have revealed that the timing of coat protein production, the guiding role of a small group of morphogenetic proteins, and several types of posttranslational modifications are essential for the fidelity of the assembly process. Assembly of the exosporium requires a set of novel proteins as well as homologues of proteins found in the outermost layers of the coat and of some of the coat morphogenetic factors, suggesting that the exosporium is a more specialized structure of a multifunctional coat. These and other insights into the molecular details of spore surface morphogenesis provide avenues for exploitation of the spore surface layers in applications for biotechnology and medicine.

中文翻译：

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孢子表面层的结构，组装和功能。

由芽孢杆菌，梭状芽胞杆菌和相关属形成的内生孢子被包裹在称为外壳的蛋白质壳中。在许多物种中，包括枯草芽孢杆菌，外壳是最外层的孢子结构，而在其他物种中，例如病原性生物炭疽杆菌和蜡状芽孢杆菌，则将孢子包裹在称为外孢子囊的附加层中。外套和外孢子在保护孢子及其环境相互作用中均具有作用。两种结构的组装是母细胞的功能，母细胞是发育中的孢子囊的两个细胞腔室之一。枯草芽孢杆菌的研究表明，外壳蛋白生产的时机，一小组形态发生蛋白的指导作用以及几种类型的翻译后修饰对于组装过程的准确性至关重要。外生孢子的组装需要在外套的最外层和一些外套形态发生因子中发现的一组新蛋白质以及蛋白质的同源物，这表明外孢子是多功能外套的更特殊的结构。对孢子表面形态发生的分子细节的这些和其他见解为生物技术和医学应用中的孢子表面层的利用提供了途径。