Duncan C L, King G J, Frieben W R
J Bacteriol. 1973 May;114(2):845-59. doi: 10.1128/jb.114.2.845-859.1973.
A large paracrystalline inclusion is formed by certain strains of Clostridium perfringens type A during spore morphogenesis. In most cell thin sections, the inclusion appeared rod-shaped when sectioned at an angle perpendicular to its longer axis, and circular or oval-shaped when sectioned at an angle parallel to its longer axis. Measurements performed on electron micrographs of inclusions sectioned to reveal the rod shape indicated a fairly consistent thickness (width) of 192 +/- 23 nm. The length of the inclusions varied considerably with a maximum of approximately 2,120 nm being observed. Ultrastructurally, the inclusion was composed of closely packed, periodically spaced, parallel layers. Usually a single inclusion was randomly located in the cytoplasm of the cell. Two inclusions per cell were rarely observed. The inclusion was formed only by ent(+) strains of C. perfringens. Mutants of the ent(+) strain NCTC 8798 that were altered in their sporulating and enterotoxin-producing capacities and revertants of these mutants were tested for inclusion formation. The results indicate that, as with the ent(+) trait, a direct relationship exists between inclusion formation and spore formation. The synthesis of enterotoxin, formation of a morphologically distinct inclusion, and the initial deposition of discontinuous coat fragments around the forespore appear to be events closely related in time during spore morphogenesis.
A型产气荚膜梭菌的某些菌株在孢子形态发生过程中会形成一种大的副晶质包涵体。在大多数细胞超薄切片中，当沿垂直于其长轴的角度切片时，包涵体呈杆状，而当沿平行于其长轴的角度切片时，呈圆形或椭圆形。对显示杆状的包涵体电子显微照片进行测量表明，其厚度（宽度）相当一致，为192±23纳米。包涵体的长度变化很大，观察到的最大值约为2120纳米。在超微结构上，包涵体由紧密堆积、周期性间隔的平行层组成。通常单个包涵体随机位于细胞的细胞质中。很少观察到每个细胞有两个包涵体。该包涵体仅由产气荚膜梭菌的ent(+)菌株形成。对ent(+)菌株NCTC 8798的孢子形成和产肠毒素能力发生改变的突变体以及这些突变体的回复体进行了包涵体形成测试。结果表明，与ent(+)性状一样，包涵体形成与孢子形成之间存在直接关系。肠毒素的合成、形态上不同寻常的包涵体的形成以及前芽孢周围不连续包膜片段的初始沉积似乎是孢子形态发生过程中在时间上密切相关的事件。
