Novotny C, Carnahan J, Brinton C C
J Bacteriol. 1969 Jun;98(3):1294-306. doi: 10.1128/jb.98.3.1294-1306.1969.
The effect of mechanical agitation (blending) on the removal of F pili, type I pili, and flagella from Hfr (high-frequency recombinant) and resistance transfer factor (RTF) fi(+)Escherichia coli cells was studied by electron microscopy. The reduction in number and length of appendages was measured as a function of blendor speed under standard conditions of temperature, medium, cell density, and blendor configuration. F pili and flagella were removed within the same narrow range of blendor speeds. Type I pili were removed within a higher and broader range of speeds. The speed which reduced the average length of type I pili to 50% was 3.5 times the speed which reduced the average length of F pili to 50%. None of the speeds employed inhibited cell growth, viability, or the ability to produce cell appendages. The kinetics of reappearance of F pili and type I pili after removal by blending were also different. F pili grew out very rapidly, reaching 50% of their full length in 30 sec and their full length in 4 to 5 min. The number of attached F pili per cell also increased rapidly, reaching a constant value in 4 to 5 min. After 5 min, F pilus lengths were distributed around a modal value of about 1.2 mum, and the numbers of F pili per cell were distributed according to a Poisson distribution, with an average of 1.0 per cell. These reappearance kinetics, length distributions, and number distributions are consistent with a model of F-pilus outgrowth in which new F pili appear at random locations on the cell surface at an average rate of about once every 4 min, grow to their characteristic length in about 4 min, and then separate from the cell. F pili which had separated could absorb to the cells, leading to the presence of two classes of F pili on cells: those in the process of natural out-growth and those attached by absorption. Type I pili increased in length much more slowly than did F pili, although the fraction of cells having visible type I pili increased very rapidly after blending because of the large number of type I pili per cell. The fraction of flagellated cells increased even more slowly, reaching only 30% of the unblended fraction in 30 min. The application of blending spectra and reappearance kinetics to the identification of cell functions with surface structures is discussed.
通过电子显微镜研究了机械搅拌（混合）对从高频重组（Hfr）和抗性转移因子（RTF）F⁺大肠杆菌细胞中去除F菌毛、I型菌毛和鞭毛的影响。在温度、培养基、细胞密度和搅拌器配置的标准条件下，测量附属物数量和长度的减少作为搅拌器速度的函数。F菌毛和鞭毛在相同的较窄搅拌器速度范围内被去除。I型菌毛在更高且更宽的速度范围内被去除。将I型菌毛平均长度减少到50%的速度是将F菌毛平均长度减少到50%的速度的3.5倍。所采用的任何速度均未抑制细胞生长、活力或产生细胞附属物的能力。混合去除后F菌毛和I型菌毛重新出现的动力学也不同。F菌毛生长非常迅速，在30秒内达到其全长的50%，在4至5分钟内达到全长。每个细胞上附着的F菌毛数量也迅速增加，在4至5分钟内达到恒定值。5分钟后，F菌毛长度分布在约1.2μm的众数周围，每个细胞的F菌毛数量根据泊松分布，平均每个细胞1.0根。这些重新出现的动力学、长度分布和数量分布与F菌毛生长模型一致，在该模型中，新的F菌毛以约每4分钟一次的平均速率随机出现在细胞表面，在约4分钟内生长到其特征长度，然后与细胞分离。已分离的F菌毛可以吸附到细胞上，导致细胞上存在两类F菌毛：处于自然生长过程中的菌毛和通过吸附附着的菌毛。I型菌毛长度增加的速度比F菌毛慢得多，尽管由于每个细胞有大量的I型菌毛，混合后具有可见I型菌毛的细胞比例增加非常迅速。有鞭毛的细胞比例增加得更慢，在30分钟内仅达到未混合比例的30%。讨论了混合光谱和重新出现动力学在通过表面结构鉴定细胞功能方面的应用。
