Wilkins J R, Darnell W L, Boykin E H
Appl Microbiol. 1972 Nov;24(5):786-97. doi: 10.1128/am.24.5.786-797.1972.
Cinemicrographic studies revealed that the development of elongated subsurface colonies of Staphylococcus aureus in soft agar (<0.2% agar) originated with a colony-forming unit of about 10 to 20 cells. It was then observed that small clusters of 3 to 12 cells broke off from the main colony unit and drifted away under the combined influence of gravity and Brownian motion. Once the downward or slightly sideward motion of the small clusters ceased, the clusters would continue to increase in size; at the same time, additional small clusters broke off, and the cycle was repeated until the entire colony was formed. Displacement and velocity measurements were made on the drifting small clusters. When compared with the dimensional growth rate and geometry of the subsurface colony, these showed that a correlation existed between the movement and velocity of the small clusters and the subsequent colony development. A relationship between the role of gravity reported in these results and the development of spherical colonies after rotation on a clinostat is suggested.
电影显微摄影研究表明，金黄色葡萄球菌在软琼脂（琼脂含量<0.2%）中形成细长的表面下菌落，其起始于一个约由10到20个细胞组成的菌落形成单位。随后观察到，3到12个细胞的小簇从主要菌落单位脱离，并在重力和布朗运动的共同影响下漂移开去。一旦小簇向下或略微侧向的运动停止，这些小簇会继续增大尺寸；与此同时，更多小簇脱离，如此循环往复，直至整个菌落形成。对漂移的小簇进行了位移和速度测量。与表面下菌落的尺寸生长速率和几何形状相比，这些测量结果表明，小簇的运动和速度与随后的菌落发育之间存在相关性。这些结果中所报告的重力作用与在回转器上旋转后形成球形菌落之间的关系被提了出来。
